The expression of trefoil factor family member 2 in increased at an acidic pH

Trefoil factor family member 2 (Tff2) is significantly involved in intestinal tumor growth in ApcMin/+ mice, which can be used as a human colon cancer model. TFF2, which encodes TFF2 (spasmolytic protein 1) is highly expressed in human cancer tissues, including the pancreas, colon and bile ducts, as well as in normal gastric and duodenum tissues. By contrast, TFF2 exhibits low expression levels in other normal tissues, including the small and large intestine. Furthermore, TFF2 expression has not been detected in DLD-1 cells, a cell line derived from human colon cancer. What induces TFF2 expression in normal and tumor cells is still unknown. Highly malignant tumor tissues are characterized by higher temperatures and lower pH (6.2-6.9) than in normal tissues, where normal pH ranges from 7.2 to 7.4. This microenvironment exacerbates malignancy by promoting the acquisition of cell death resistance, drug resistance and immune escape. Therefore, the present study examined how TFF2 expression is affected in cultured cells that imitate the tumor tissue microenvironment. The incubation temperature was increased from 37 to 40°C, but no expression of TFF2 was induced. Subsequently, a culture solution with an acidic pH was prepared to simulate the Warburg effect in tumors. TFF2 expression was increased by 42.8- and 5.8-fold in cells cultured in acidic medium at pH 6.5 and 6.8 compared with at pH 7.4, respectively, as determined using the relative quantification method following quantitative polymerase chain reaction. The present study also analyzed fluctuations in the expression levels of genes other than TFF2, under acidic conditions. Acidic conditions upregulated the expression of genes related to cell membranes and glycoproteins, based on the Database for Annotation, Visualization, and Integrated Discovery. In conclusion, TFF2 was highly expressed under acidic conditions, implying that it may have an important function in protecting the plasma membrane from acidic environments in both normal and cancer cells. These findings warrant further investigation of TFF2 as a target of cancer therapy and diagnosis.

Embryonic thermal manipulation of poultry birds: Lucrative and deleterious effects

The major efforts to improve feed conversion, increase the body weight and breast muscle yield of broilers have been focused on feeding and management at the post hatch period. However, incubation temperature is the most significant factor for the egg hatching rate, chick quality, and post hatch performance. Therefore, incubation factors affecting the performance should be taken with necessary precautions. Incubation temperature not only affects the early development of the hatchlings but also has a lasting impact on the characteristics of the chicks, such as final body weight and meat quality traits. This article provides an overview about embryonic thermal manipulation (TM) of domestic fowls and review the lucrative and deleterious effects of embryonic TM on embryo development, muscle growth, thermotolerance acquisition, and immunity.

Effect of thermal manipulation on embryonic development, hatching process, and chick quality under heat-stress conditions

Thermal stress is a risk that threatens poultry welfare and productivity. Thermal manipulation during egg incubation is considered a prevention strategy used to mitigate the detrimental effects of high ambient temperatures on birds. This study aimed to investigate the impact of thermal manipulation, applied to chicken breeder's eggs during the incubation period, on embryonic development, hatching characteristics, and chick quality, as well as posthatch thermotolerance and performance. A total of 1,200 fertile eggs were randomly and equally assigned into 2 groups of 3 replicates (200 eggs/replicate), using a randomized experimental design followed by t test. The first group eggs (G1) were subjected to a commercial setter temperature of 37.5°C with 55% relative humidity (RH) throughout the incubation period (1-18 d) and served as a control, while the second group eggs (G2) were treated the same commercial setter conditions until the 11th day of the incubation, then the eggs were exposed to a higher temperature of 39.5°C with 60% RH for 4 h daily from the 12th to the 18th day of incubation. All eggs in both groups were exposed to the same temperature condition of 37.2°C with 70% RH from the 19th to the 22nd days of the incubation (hatching period). Three hundred hatched female chicks per each treatment group were transferred into a closed-system house and distributed randomly into 20 floor pens (15 birds per pen). At the 8th week of age, birds were exposed to a daily heat challenge by raising the temperature to 35°C for 6 h until the 18th week of the chick's age. According to the results, thermal manipulation at 12 to 18 d of egg incubation positively (P ≤ 0.05) affected several studied traits. It improved some embryonic development traits, such as embryonic weight and tibia length, as well as some hatching parameters, such as hatching time and pipped eggs. It also improved hatched chick quality traits, including the chick's weight, length, and activity. In addition, it enhanced the posthatch chick's thermotolerance and body weight. Hatched chicks of G2 had significantly (P ≤ 0.05) higher total protein, albumin, IgM, glucose, calcium, total antioxidant, and T3 than G1 chicks. They also had significantly (P = 0.001) higher body weight (23%) at the 18th week of age than G1, as well as a lower feed conversion ratio (20.71%) than G1 chicks at 8 to 18 wk of age. Therefore, it is recommended to apply thermal manipulation during egg incubation, particularly at 12 to 18 d, for its positive effects on the pre- and posthatch performance.

Simple cryopreservation protocol for Luffa pollen: enhancing breeding efficiency

This study aimed to develop a long-term pollen storage protocol for Luffa species (L. acutangula, L. cylindrica, L. echinata, and L. graveolens) and assess its potential for crop improvement. The optimal medium for in vitro pollen germination varied by species, with Brewbaker and Kwack (BK) medium with 10% sucrose suitable for L. acutangula, L. cylindrica, and L. echinata, and BK medium with 3% sucrose ideal for L. graveolens. Overestimation in staining tests compared to in vitro pollen germination was observed. The best results for cryopreservation were achieved with desiccation periods of 20, 30, and 40 min, maintaining moisture content between 14.04% and 18.55%. Pollen viability was negatively correlated with storage temperature (25, 4, and -20°C) and duration. Cryopreserved pollen at -196°C exhibited the highest viability over a prolonged period (2 months) and was comparable to fresh pollen in terms of germination, ovule fertilization, and fruit and seed set. This study presents a simple and reproducible pollen cryopreservation protocol applicable across Luffa species, facilitating long-term storage and its use in crop improvement efforts.

Population divergence in maternal investment and embryo energy use and allocation suggests adaptive responses to cool climates

The thermal sensitivity of early life stages can play a fundamental role in constraining species distributions. For egg-laying ectotherms, cool temperatures often extend development time and exacerbate developmental energy cost. Despite these costs, egg laying is still observed at high latitudes and altitudes. How embryos overcome the developmental constraints posed by cool climates is crucial knowledge for explaining the persistence of oviparous species in such environments and for understanding thermal adaptation more broadly. Here, we studied maternal investment and embryo energy use and allocation in wall lizards spanning altitudinal regions, as potential mechanisms that enable successful development to hatching in cool climates. Specifically, we compared population-level differences in (1) investment from mothers (egg mass, embryo retention and thyroid yolk hormone concentration), (2) embryo energy expenditure during development, and (3) embryo energy allocation from yolk towards tissue. We found evidence that energy expenditure was greater under cool compared with warm incubation temperatures. Females from relatively cool regions did not compensate for this energetic cost of development by producing larger eggs or increasing thyroid hormone concentration in yolk. Instead, embryos from the high-altitude region used less energy to complete development, that is, they developed faster without a concomitant increase in metabolic rate, compared with those from the low-altitude region. Embryos from high altitudes also allocated relatively more energy towards tissue production, hatching with lower residual yolk: tissue ratios than low-altitude region embryos. These results are consistent with local adaptation to cool climate and suggest that this is underpinned by mechanisms that regulate embryonic utilisation of yolk reserves and its allocation towards tissue, rather than shifts in maternal investment of yolk content or composition.

Comparison of volatile metabolic profiles in fermented milk of Streptococcus thermophilus during the postripening period at different incubation temperatures

Streptococcus thermophilus has been extensively applied in fermented milk. This study used gas chromatography-ion mobility spectroscopy to determine and evaluate the volatile metabolites in raw milk, milk fermented at 37°C, and milk fermented at 42°C. Ten discriminatory volatile metabolites were identified at different incubation temperatures: acetone, 2-heptanone, 2-pentanone, 2-hexanone, butanal, hexanal, ethyl acetate, 3-methylbutanal, 3-methylbutanoic acid, and 2-methylpropanoic acid, indicating that fermentation temperature affected the spectrum of volatiles in milk fermented by different strains of S. thermophilus. Specifically, fermentation at 37°C led to accumulation of short-chain fatty acids, whereas fermentation at 42°C enriched ketones and other flavor substances in the fermented milk, enhancing the flavor of the product. This work examined the differences between the volatile metabolites produced by different S. thermophilus strains fermented at different temperatures to evaluate the effect of temperature on the metabolic pathways.

Effects of ambient temperature and available sugar on bacterial community of Pennisetum sinese leaf: An in vitro study

The present in vitro study investigated the effects of temperature and available sugar on the bacterial community of Pennisetum sinese leaf during fermentation. P. sinese leaves were cultured in MRS broth containing 0.4 and 1.6 g sugar and incubated at 25°C and 45°C for 9, 18, and 36 h. The results showed that the dominant phyla during sugar fermentation were Firmicutes, followed by Proteobacteria and Bacteroidetes. Compared to a low incubation temperature (25°C), a high incubation temperature (45°C) decreased the relative abundances of Exiguobacterium and Acinetobacter and increased those of Bacillus and Paenibacillus. Leaf samples incubated at 25°C showed higher bacterial alpha diversity indices than those incubated at 45°C. Principal coordinate analysis revealed that the bacterial community structure was altered by the high incubation temperature. Sugar concentration of 1.6 g/50 ml increased the relative abundances of Bacillus and Klebsiella but decreased those of Paenibacillus and Serratia as compared to sugar concentration of 0.4 g/50 ml. pH was the primary factor that influenced the succession of bacterial communities during sugar fermentation in P. sinese leaves. In conclusion, ambient temperatures (25°C and 45°C) and high sugar concentration restructured the bacterial communities on P. sinese leaves by facilitating the dominance of Bacillus and Paenibacillus. This study provided insights into the mechanisms by which bacterial communities on P. sinese leaves are enriched.

Warmer incubation temperatures and later lay-orders lead to shorter telomere lengths in wood duck (Aix sponsa) ducklings

The environment that animals experience during development shapes phenotypic expression. In birds, two important aspects of the early-developmental environment are lay-order sequence and incubation. Later-laid eggs tend to produce weaker offspring, sometimes with compensatory mechanisms to accelerate their growth rate to catch-up to their siblings. Further, small decreases in incubation temperature slow down embryonic growth rates and lead to wide-ranging negative effects on many posthatch traits. Recently, telomeres, noncoding DNA sequences at the end of chromosomes, have been recognized as a potential proxy for fitness because longer telomeres are positively related to lifespan and individual quality in many animals, including birds. Although telomeres appear to be mechanistically linked to growth rate, little is known about how incubation temperature and lay-order may influence telomere length. We incubated wood duck (Aix sponsa) eggs at two ecologically-relevant temperatures (34.9°C and 36.2°C) and measured telomere length at hatch and 1 week after. We found that ducklings incubated at the lower temperature had longer telomeres than those incubated at the higher temperature both at hatch and 1 week later. Further, we found that later-laid eggs produced ducklings with shorter telomeres than those laid early in the lay-sequence, although lay-order was not related to embryonic developmental rate. This study contributes to our broader understanding of how parental effects can affect telomere length early in life. More work is needed to determine if these effects on telomere length persist until adulthood, and if they are associated with effects on fitness in this precocial species.

Temperature Incubation Influences Gonadal Gene Expression during Leopard Gecko Development

During development, sexual differentiation results in physiological, anatomical and metabolic differences that implicate not only the gonads but also other body structures. Sex in Leopard geckos is determined by egg incubation temperature. Based on the premise that the developmental decision of gender does not depend on a single gene, we performed an analysis on E. macularius to gain insights into the genes that may be involved in gonads' sexual differentiation during the thermosensitive period. All the genes were identified as differentially expressed at stage 30 during the labile phase of sex differentiation. In this way, the expression of genes known to be involved in gonadal sexual differentiation, such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRLand PRL-R, was investigated. Other genes putatively involved in sex differentiation were sought by differential display. Our findings indicate that embryo exposure to a sex-determining temperature induces differential expression of several genes that are involved not only in gonadal differentiation, but also in several biological pathways (ALDOC, FREM1, BBIP1, CA5A, NADH5, L1 non-LTR retrotransposons, PKM). Our data perfectly fit within the new studies conducted in developmental biology, which indicate that in the developing embryo, in addition to gonadal differentiation, sex-specific tissue and metabolic polarization take place in all organisms.

The Pork Meat or the Environment of the Production Facility? The Effect of Individual Technological Steps on the Bacterial Contamination in Cooked Hams

The aim of this study was to analyse the influence of the contamination level of fresh meat on the bacterial population in raw material before cooking and on the microbiota of cooked hams following heat treatment. The effect of incubation temperatures of 6.5 and 15 °C on the results obtained was also evaluated during the bacteriological investigation. The total viable count (TVC), the number of Enterobacteriaceae and lactic acid bacteria (LAB) were determined in the samples. LAB were isolated from 13 samples out of the 50 fresh meat samples. The species most frequently detected included Latilactobacillus sakei, Leuconostoc carnosum, Enterococcus gilvus, Latilactobacillus curvatus, and Leuconostoc gelidum. The meat sampled after the brine injection and tumbler massaging showed higher bacterial counts compared to fresh meat samples (p < 0.001). The heat treatment destroyed the majority of the bacteria, as the bacterial counts were beneath the limit of detection with a few exceptions. Although the primary cultivation of samples of cooked hams did not reveal the presence of LAB, their presence was confirmed in 11 out of 12 samples by a stability test. Bacteria of the genus Leuconostoc were the most numerous.

Impact of Treating Hatching Eggs with Curcumin after Exposure to Thermal Stress on Embryonic Development, Hatchability, Physiological Body Reactions, and Hormonal Profiles of Dokki-4 Chickens

Simple Summary

Curcumin has been used as a suitable feed supplement for poultry to improve several hematological and biochemical indicators, diminish heat stress, and increase antioxidant activity. This experiment evaluated the effects of incubation temperatures and spraying hatching eggs with curcumin during the incubation phase on chick embryo development, hatchability, physiological body reactions, and hormonal profiles of Dokki 4 chickens. The findings indicated that the relative water loss and dead after piping in the chronic incubation temperature group were significantly increased compared with the normal incubation temperature group. Post-hatch, the triiodothyronine level in the high incubation temperature group was significantly decreased than in the control group. Regarding curcumin treatments, relative water loss from eggs and the hatchability of fertile eggs in treated groups significantly increased, while body surface temperature significantly decreased compared with the control.

Abstract

This study evaluated the impact of incubation temperature and spraying hatching eggs with curcumin during the early embryogenesis phase on chick embryo developments, hatchability, physiological body reactions, and hormonal profiles of Dokki 4 chickens. A total of 720 fertile eggs were equally distributed into two groups. In the first group, the eggs were incubated at normal incubation temperature/NIT (37.8 °C and 55–60% RH) for up to 19 days of incubation, whereas those in the second group were incubated in the same conditions except from 6 to 8 day, in which they were daily exposed to chronic incubation temperature/CIT (39.0 °C) for 3 h. Each group was classified into four curcumin treatment doses; the 1st treatment (control) was sprayed with distilled water, while the 2nd, 3rd, and 4th treatments were sprayed with 250, 500, and 1000 mg curcumin/liter distilled water. The results indicated that the lowest hatchability of fertile eggs (%) was obtained in the CIT group (p = 0.02), whereas the highest body surface temperature/BST compared in the NIT group (p = 0.01). Regarding curcumin treatments, the percentages of heart, gizzard, spleen, and T3 hormone levels in the treated group were significantly increased, while the H/L ratio was significantly reduced (p = 0.001) compared with the control. At 8 weeks of age, the testes and ovary percentages in treated groups were significantly (p = 0.05) increased compared with the control. In conclusion, exposure of hatching eggs to high thermal stress (39 °C) during the incubation phase had deleterious effects on chick performance and T3 hormone level. Moreover, spraying hatching eggs had beneficial impacts on growth, reproductive organs, T3 hormone level, and reducing H/L ratio.

Analysis of Environmental Variables and Carbon Input on Soil Microbiome, Metabolome and Disease Control Efficacy in Strawberry Attributable to Anaerobic Soil Disinfestation

Charcoal rot and Fusarium wilt, caused by Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae, respectively, are major soil-borne diseases of strawberry that have caused significant crop losses in California. Anaerobic soil disinfestation has been studied as an industry-level option to replace soil fumigants to manage these serious diseases. Studies were conducted to discern whether Gramineae carbon input type, incubation temperature, or incubation duration influences the efficacy of this disease control tactic. In experiments conducted using 'low rate' amendment applications at moderate day/night temperatures (24/18 °C), and carbon inputs (orchard grass, wheat, and rice bran) induced an initial proliferation and subsequent decline in soil density of the Fusarium wilt pathogen. This trend coincided with the onset of anaerobic conditions and a corresponding generation of various anti-fungal compounds, including volatile organic acids, hydrocarbons, and sulfur compounds. Generation of these metabolites was associated with increases in populations of Clostridium spp. Overall, carbon input and incubation temperature, but not incubation duration, significantly influenced disease suppression. All Gramineae carbon inputs altered the soil microbiome and metabolome in a similar fashion, though the timing and maximum yield of specific metabolites varied with input type. Fusarium wilt and charcoal rot suppression were superior when anaerobic soil disinfestation was conducted using standard amendment rates of 20 t ha-1 at elevated temperatures combined with a 3-week incubation period. Findings indicate that anaerobic soil disinfestation can be further optimized by modulating carbon source and incubation temperature, allowing the maximum generation of antifungal toxic volatile compounds. Outcomes also indicate that carbon input and environmental variables may influence treatment efficacy in a target pathogen-dependent manner which will require pathogen-specific optimization of treatment protocols.

Influence of short-term temperature drops on sex-determination in sea turtles

All sea turtles exhibit temperature-dependent sex-determination, where warmer temperatures produce mostly females and cooler temperatures produce mostly males. As global temperatures continue to rise, sea turtle sex-ratios are expected to become increasingly female-biased, threatening the long-term viability of many populations. Nest temperatures are dependent on sand temperature, and heavy rainfall events reduce sand temperatures for a brief period. However, it is unknown whether these short-term temperature drops are large and long enough to produce male hatchlings. To discover if short-term temperature drops within the sex-determining period can lead to male hatchling production, we exposed green and loggerhead turtle eggs to short-term temperature drops conducted in constant temperature rooms. We dropped incubation temperature at four different times during the sex-determining period for a duration of either 3 or 7 days to mimic short-term drops in temperature caused by heavy rainfall in nature. Some male hatchlings were produced when exposed to temperature drops for as little as 3 days, but the majority of male production occurred when eggs were exposed to 7 days of lowered temperature. More male hatchlings were produced when the temperature drop occurred during the middle of the sex-determining period in green turtles, and the beginning and end of the sex-determining period in loggerhead turtles. Inter-clutch variation was evident in the proportion of male hatchlings produced, indicating that maternal and or genetic factors influence male hatchling production. Our findings have management implications for the long-term preservation of sea turtles on beaches that exhibit strongly female-biased hatchling sex-ratios.

Thermal effects in rainbow trout (Oncorhynchus mykiss) F1 embryos (farmed female × wild thermal-resistant male)

The aim of this work was to investigate the response of rainbow trout embryos (Oncorhynchus mykiss) (i.e., survival, size at hatching, time to hatching, malformations) to four incubation temperatures (5.8, 8.9, 14.0 and 16.8°C), taking into account the origin of the male parental genome and comparing pure farmed and F1 embryos (farmed female × wild thermal-resistant male). Several consequences of thermal stress were observed: lower accumulated thermal units (ATU) at hatching at high temperatures, and lower survival, shorter hatched free embryos and less-consumed yolk sac at extreme temperatures. The effect of the thermal-adapted male parental genome was shown only in the lower percentage of incompletely hatched free embryos in the F1 families. It appears that to obtain greater modification of thermal performance during early development, the adapted genome of the wild thermal-resistant population has to be included through maternal inheritance, thus producing a stabilized strain selected for domesticity, growth and thermal adaptation.

Periodic Cooling during Incubation Alters the Adrenocortical Response and Posthatch Growth in Zebra Finches

AbstractIn birds, incubation temperature is critically deterministic for a range of traits. When parents leave the nest to forage, developing embryos can be exposed to cooling events that represent thermal stress. To investigate the consequences of periodic cooling on offspring development and physiology, we exposed zebra finch embryos to cooling events throughout the incubation period. We then compared embryonic survival, egg mass change, incubation duration, posthatch growth, and adrenocortical response of these individuals with embryos reared at a constant optimal temperature of 37.4°C and embryos reared at a constant suboptimal temperature of 36.4°C, the mean incubation temperature of periodically cooled embryos. There were no differences in embryonic survival or egg mass change during incubation, but individuals exposed to periodic cooling had longer incubation periods than those from the 37.4°C treatment and shorter incubation periods than those from the 36.4°C treatment. Periodically cooled individuals showed slower posthatch growth in comparison with both constant-temperature treatments, but this did not impact adult body size. Treatment groups did not differ in their adrenocortical response, but embryos exposed to periodic cooling and a constant temperature of 37.4°C were able to habituate to repeated capture and restraint stress, while individuals exposed to the constant temperature of 36.4°C were not. These results point to the differential impacts of cooling events versus constant low temperatures during incubation on posthatch growth and physiology and may represent a way for parents to devote less energy toward incubation while still ensuring offspring success.

Extreme rainfall events and cooling of sea turtle clutches: Implications in the face of climate warming

Understanding how climate change impacts species and ecosystems is integral to conservation. When studying impacts of climate change, warming temperatures are a research focus, with much less attention given to extreme weather events and their impacts. Here, we show how localized, extreme rainfall events can have a major impact on a species that is endangered in many parts of its range. We report incubation temperatures from the world's largest green sea turtle rookery, during a breeding season when two extreme rainfall events occurred. Rainfall caused nest temperatures to drop suddenly and the maximum drop in temperature for each rain-induced cooling averaged 3.6°C (n = 79 nests, min = 1.0°C, max = 7.4°C). Since green sea turtles have temperature-dependent sex determination, with low incubation temperatures producing males, such major rainfall events may have a masculinization effect on primary sex ratios. Therefore, in some cases, extreme rainfall events may provide a "get-out-of-jail-free card" to avoid complete feminization of turtle populations as climate warming continues.

Effects of eggshell temperature pattern during incubation on primary immune organ development and broiler immune response in later life

Eggshell temperature (EST) during incubation greatly affects embryo development, chick quality at hatch, and subsequently various broiler physiological systems. Until now, a constant EST of 37.8°C seems optimal. Data on effects of EST patterns on immune organ development and subsequent broiler immune response are, however, scarce. A higher EST of 38.9°C in week 2 and/or a lower EST of 36.7°C in week 3 of incubation potentially positively affect embryo immune organ development and broiler immune response post hatch. Broiler eggs (n = 468) were incubated at 4 different EST patterns (n = 117 eggs/treatment) from week 2 of incubation onward. Week 1 (embryonic age (E)0 < E7) EST was 37.8°C for all eggs. Week 2 (E7 < E14) EST was either 37.8°C (Control) or 38.9°C (Higher), and week 3 (E14 - /hatch) EST was either Control or 36.7°C (Lower). At hatch, histology of bursal follicles and jejunum villi and crypts were determined as well as heterophil to lymphocyte ratio (H:L) (n = 49). Posthatch, both sexes were grown in 8 pens/treatment for 6 wk (n = 320). Natural antibodies (NAb) were determined at day 14, 22, and slaughter (day 41 or 42) as an indicator of immunocompetence and response to a Newcastle disease (NCD) vaccination was determined by antibody levels at day 22 and slaughter (n = 128). Results showed no interaction EST week 2 × EST week 3, except for jejunum histology. Higher EST in week 2 resulted in lower cell density within bursal follicles (P = 0.02) and a tendency for lower H:L (P = 0.07) at hatch, and higher NCD titers at slaughter (P = 0.02) than Control EST. Lower EST in week 3 resulted at hatch in higher cell density within bursal follicles, higher H:L (both P < 0.05), and a tendency for a higher posthatch mortality rate than control EST (P = 0.10). In conclusion, higher EST in week 2 during incubation may benefit embryonic immune organ development and posthatch broiler immunocompetence, while lower EST in week 3 showed opposite indications.

Systematic monitoring of glanders-infected horses by complement fixation test, bacterial isolation, and PCR

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A modified PCR protocol improved the diagnostic sensibility for glanders.

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Horses with chronic glanders disease may show false negative serology results.

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The cold CFT is recommended in Brazilian equine health program.

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Burkholderia mallei isolation and detection were performed in São Paulo state, Brazil.

Glanders is an equine zoonosis caused by Burkholderia mallei that is responsible for considerable economic loss. Complement fixation testing (CFT) using warm or cold incubation are recommended by the OIE, but many routinely used detection tests may present misleading results. To increase accuracy of glanders diagnosis and establish an appropriate protocol in collaboration with the National Equine Health Program, seven horses positive for glanders kept in isolation in Brazil were examined fortnightly by CFT, microbiological screening, and molecular testing. Warm and cold serologies with USDA and c.c.Pro antigens, respectively, were performed on 132 samples using the US Department of Agriculture protocol. The warm and cold serologies showed, respectively,12.9% and 17.3% seroreactive, 85.7% and 65.2% non-reactive, 0.8% and 3% inconclusive, and 0% and 2.3% anticomplementary. The agreement of CFT protocols was moderate. Of 213 clinical samples submitted to selective culture (167 nasal swabs, 5 ocular swabs, 3 lymph node punctures, and 38 tissue samples from four horses that died), 1.9% tested positive for B. mallei. Fourteen samples and one nasal swab (7%) tested positive with PCR. Cold CFT with the USDA and c.c.Pro antigens, in combination with PCR to increase sensitivity, may be useful for diagnosis of chronic glanders.

Thermosensitive period for sex determination of the tropical freshwater turtle Malayemys macrocephala

Many egg-laying reptiles possess temperature-dependent sex determination (TSD) in which outcome of gonadogenesis is determined by incubation temperature during a temperature-sensitive period of development. Prior studies on Malayemys macrocephala showed that incubation temperatures influence gonadal development and suggested that M. macrocephala exhibits TSD. However, information on the temperature-sensitivity period in this species was unknown until the current study. Turtle eggs were collected from rice fields in central Thailand from December 2016 to February 2017. In the laboratory, eggs were incubated at male-biased temperature (26 °C) and shifted to female-biased temperature (32 °C), or vice versa. Single shift experiments were performed systematically during embryonic stages 13-21. After hatching, sex of individual turtles was determined by histological analysis. We found that the sex determination of M. macrocephala is affected by temperature up to stage 16 of embryonic development.

Temperature-sensitive pathways may be involved in duck embryonic developmental recovery from blastoderm dormancy during hatching

1. Birds' newly oviposited blastoderms can survive several weeks in a dormant state during low-temperature storage. Previous studies demonstrated that there is a critical temperature range from 19 to 27°C for chicken embryos. Within this range, the embryo will diapause in a dormant state; once the temperature rises above this range, the blastoderm will break dormancy. 2. Clarifying the mechanism that initiates duck embryo developmental recovery from blastoderm dormancy will be helpful to change temperature control to improve hatching in poultry production. It was hypothesised that there might be some temperature-sensitive genes involved in initiating duck embryo developmental recovery from blastoderm dormancy. 3. To test this hypothesis, the transcriptome of the newly oviposited duck blastoderm and duck embryo (incubated for 48 hours) were sequenced to screen for differentially expressed genes with functions that had been predicted by bioinformatics. 4. The results showed that there were 2416 differentially expressed genes between the two groups, 53 of which were involved in temperature-sensitive pathways. The protein-protein interaction network combined these 53 temperature-sensitive genes and another group of 65 genes, which enriched the development pathway. These results suggested that temperature-sensitive genes may be involved in growth and development related pathways.

Changes in skin temperature of ovariectomized rats under different incubation temperatures

AIM

This study aimed to investigate changes in skin temperature in the main body regions of ovariectomized rats under different incubation temperatures to identify regions that are similar to hot flashes experienced by menopausal women.

METHODS

A total of 96 adult female Sprague-Dawley rats were randomly divided into sham, ovariectomized and ovariectomized with estrogen treatment groups, with treatment lasting for 4 weeks. After 3 weeks of treatment, each group was randomly divided into five subgroups and placed in separate incubators set at 4, 15, 25, and 37°C. Changes in the skin temperature in seven main regions (head, neck, chest, abdomen, back, tail, and paws) for four time intervals (0-3 min, 3-5 min, 5-10 min and 10-15 min) were monitored using infrared thermography.

RESULTS

All rats showed rapid changes in skin temperature followed by a gradual slowdown under different incubation temperatures. However, changes in ovariectomized rats were significantly different from that in normal rats, and changes on the back, tail and paws were more rapid and lasted longer. Estrogen treatment effectively controlled these abnormalities of ovariectomized rats.

CONCLUSIONS

Temperature responses in the back, tail and paws in ovariectomized rats might be similar to the face, neck and upper chest in menopausal women, where the symptoms of hot flashes are most obvious, which suggests that the back, tail and paws could be regarded as the focus of research on hot flashes, and offer theoretical foundations for mechanisms behind the occurrence of hot flashes in specific regions. Geriatr Gerontol Int 2020; ••: ••-••.

Influence of growth temperature on thermal tolerance of leading foodborne pathogens

Accurate prediction of the thermal destruction rate of foodborne pathogens is important for food processors to ensure proper food safety. When bacteria are subjected to thermal stress during storage, sublethal stresses and/or thermal acclimation may lead to differences in their subsequent tolerance to thermal treatment. The aim of the current study was to evaluate the thermal tolerance of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Staphylococcus aureus that are incubated during overnight growth in tryptic soy broth at four temperatures (15, 25, 35, and 45°C). Following incubation, the bacteria were subjected to thermal treatments at 55, 60, and 65°C. At the end of each treatment time, bacterial survival was quantified and further calculated for the thermal death decimal reduction time (D-value) and thermal destruction temperature (z-value) using a linear model for thermal treatment time (min) vs. microbial population (Log CFU/ml) and thermal treatment temperature (°C) vs. D-value, respectively, for each bacterium. Among the four bacterial species, E. coli generally had longer D-values and lower z-values than did other bacteria. Increasing patterns of D- and z-values in Listeria were obtained with the increment of incubation temperatures from 15 to 45°C. The z-values of Staphylococcus (6.19°C), Salmonella (6.73°C), Listeria (7.10°C), and Listeria (7.26°C) were the highest at 15, 25, 35, and 45°C, respectively. Although further research is needed to validate the findings on food matrix, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation hurdles applied during later stages of food processing and storage.

Combined Effects Of Low Incubation Temperature, Minimal Growth Medium, And Low Hydrodynamics Optimize Acinetobacter baumannii Biofilm Formation

BACKGROUND

Biofilm formation is an important virulence factor expressed by Acinetobacter baumannii. It shields and protects microbial cells from host immune responses, antibiotics, and other anti-infectives. Its effects on Acinetobacter baumannii infection treatments notwithstanding, important environmental factors that influence its formation have not been fully investigated.

METHODS

Biofilm formation was assessed using the qualitative modified Congo red assay and quantitative microtiter plate methods. The combined effect of temperature, medium and shear force was determined by measuring adherence (OD570 nm) in microtiter plate after incubation at 26°C, 30°C, and 37°C when biofilm-grown cells were cultured in the presence of minimal nutrient medium (EAOB) and nutrient-rich medium (TSB) without or with agitation at 50 rpm. Antibiotics susceptibility of meropenem, imipenem, and ciprofloxacin were tested with Kirby-Bauer disc method. P<0.05 was considered statistically significant in all the tests.

RESULTS

A noticeable variation in adherence was observed among the isolates cultured with both media. Biofilm forming capacity of the isolates range from 0.09-0.33. The majority of the isolates had their relative biofilm-forming capacity significantly (p<0.05) higher than the positive control, Acinetobacter baumannii ATCC 19606. The biofilm biomass during growth in nutrient-rich medium (TSB) without shaking was significantly different (p<0.05; Tukey's test) among the three temperatures tested compared with when it was cultured in EAOB without shaking. A positive correlation was observed between biofilm formation and resistance to imipenem (r=0.2889; p=0.05). There was a statistically significant difference among the median of the three source groups (p<0.05) compared with the median between the source groups.

CONCLUSION

This observation extended further the view that A. baumannii biofilm formation is enhanced when nutrient-poor medium is used at room temperature (26°C) with or without agitation compared to growth at 37°C.

Both the rooster line and incubation temperature affect embryonic metabolism and hatchling quality in laying hen crossbreds

Effects of 3 eggshell temperatures (EST; 36.7. 37.8, and 38.9°C) in 2 genetic laying hen crossbreds (AB and BB; same hen line, different rooster line) on embryonic metabolism and hatchling quality were investigated. EST were applied from day 14.5 of incubation (E14.5) until hatching. The experiment consisted of 6 consecutive batches with eggs weighing between 59 and 61 g. Heat production was determined continuously from E14.5 onward. In fresh eggs, yolk weight tended to be higher (Δ = 0.28 g; P = 0.08) in the AB crossbred than in the BB crossbred. At E14.5 and E18.5, yolk-free body mass (YFBM) and residual yolk (RY) weight did not differ between genetic crossbred and EST. Hatching time after the start of incubation was not affected by genetic crossbred, but was longer in the 36.7°C (517 h) than in the 38.9°C (505 h), with 37.8°C in between (506 h). At 6 h after hatching, no differences between crossbreds were found for chicken quality parameters, such as chicken weight, chicken length, RY, YFBM, and organ weights, but heart weight was higher in the 36.7°C EST than in the other 2 EST (Δ = 0.24 to 0.30% of YFBM, P = 0.005). Intestinal weight was higher at 36.7°C EST than at 38.9°C EST (Δ = 0.79% of YFBM; P = 0.02), with 37.8°C EST in between. Heat production between E14.5 and E18.5 was higher in the AB crossbred than in the BB crossbred (Δ = 2.61%, P < 0.001) and regardless of crossbred higher at an EST of 38.9°C than at other 2 EST (Δ = 3.59% on average; P < 0.001). Hatchling quality determined at pulling (E21.5) was not affected by EST, but AB chickens were lighter (Δ = 0.46 g; P = 0.03), had less red hocks (Δ = 0.03; P = 0.02), more red beaks (Δ = 0.10; P < 0.001), and a higher (worse) navel score (Δ = 0.11; P < 0.001) than BB chickens. It can be concluded that not only incubation temperature, but also the rooster line appears to play a role in layer crossbred embryo metabolism and hatchling quality.

Temporal characterization of wooden breast myopathy ("woody breast") severity and correlation with growth rate and lymphocytic phlebitis in three commercial broiler strains and a random-bred broiler strain

Wooden breast myopathy (WBM), or "woody breast" or "wooden breast" affects modern, rapidly growing, high breast-yield broiler chickens. Decreased meat quality due to undesirable organoleptic properties and condemnation of affected breast meat cause economic losses. The pathogenesis of WBM remains unknown. In this study, WBM lesion development was determined in three modern broiler strains and Athens Canadian Random Bred (ACRB) broilers, a 1950s unselected broiler chicken. Correlations between WBM severity and incubation temperature profile, sex, strain, body weight, and lymphocytic phlebitis were also determined. At 2, 4, 6, and 8 weeks of age, samples of breast muscle from 10 male and 10 female birds from each strain, incubated under optimal or low-early, high-late temperatures, were scored histologically for severity of WBM and lymphocytic phlebitis. WBM lesions, identified as early as 2 weeks, became progressively more severe with age and growth in the three commercial broiler strains. WBM severity was significantly correlated with lymphocytic phlebitis and body weight. Lymphocytic phlebitis and minimal WBM were present in the ACRB broilers at all samplings, but did not progress in severity over time. There were no significant differences in severity of WBM among the commercial broiler strains, between sexes, or between incubation temperature profiles. The positive correlation between WBM severity and lymphocytic phlebitis indicates vascular injury is likely an important factor in the pathogenesis. Mild muscle lesions in ACRB birds without overt clinical signs indicate subclinical muscle disease may have been present in broilers prior to the description of WBM.

Competitive interaction on dual-species biofilm formation by spoilage bacteria, Shewanella baltica and Pseudomonas fluorescens

AIMS

This study aims to characterize the biofilm produced by mono- and dual-species of Shewanella baltica and Pseudomonas fluorescens as fish spoilers at the different incubation temperature, and to elucidate the interactive behaviour of dual-species biofilm development.

METHODS AND RESULTS

The mono- and dual-species biofilm formation and adhesion characteristics of S. baltica and P. fluorescens were evaluated by using crystal violet staining, scanning electron microscopy and confocal laser scanning microscopy. Results showed that P. fluorescens had significantly higher biofilm biomass and polysaccharides production than S. baltica, and two isolates reached the maximum biofilm biomass during the early stationary phase. Lower biomass and polysaccharides in dual-species biofilms were observed compared to mono-species of P. fluorescens. Meanwhile, S. baltica and P. fluorescens formed fragile and viscous pellicles with different spatial architectures respectively. In dual-species pellicle few large microcolonies were dominated by P. fluorescens. Compared to mono-species of PF07, adherent cell population and biofilm thickness at the developing phase significantly decreased, and biofilm-forming cycle prolonged in the dual-species biofilms. Biofilm formation and adhesion of mono- and dual-species at 4 or 15°C were significantly higher than at 30°C during the same phase. The culture supernatant extracts of the two spoilage strains greatly inhibited biofilm development to each other.

CONCLUSIONS

Shewanella baltica and P. fluorescens had different biofilm and pellicle characteristics, and the inhibitory development on dual-species biofilm was associated with the competitive interaction by the two psychrotrophic spoilage bacteria.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work contributes to a better understanding of interactive behaviour of multispecies biofilm communities by psychrotrophic spoilage bacteria at low temperature, which could contribute to further control contamination of spoilage organism during the preservation and processing of aquatic products.

Effect of embryonic thermal manipulation on heat shock protein 70 (HSP70) expression and subsequent immune response to post-hatch lipopolysaccharide challenge in Pekin ducklings

During the course of multi-stage incubation, small locational differences in incubation temperature within a machine are not uncommon and so the goal of this study was to study the immune response of ducklings exposed to thermal manipulation during incubation. Commercial Pekin duck eggs (n = 200) were distributed among four treatment: SS-Control (37.5°C from embryonic day [ED] 1 to 25); SS-LPS (37.5°C from ED1 to 25 + LPS at D0 [hatch]); HH-LPS (38°C from ED1 to 25+ LPS at D0); SH-LPS (37.5°C from ED1 to 10 and 38°C from ED 11 to 25 + LPS at D0). At D0, ducklings received a lipopolysaccharide (LPS) injection. At D1 and D5, the HH-LPS treatment significantly reduced body weight (P ≤ 0.05). At D1 and D3 post-LPS injection, the SH-LPS and HH-LPS treatments significantly reduced splenic and bursal heat shock protein 70 (HSP70), mRNA abundance, and macrophage nitric oxide production compared with the SS-LPS treatment (P ≤ 0.05). At D1, the HH-LPS and SH-LPS treatments had increased splenic IL-10 mRNA and lower MHC I mRNA compared with the SS-LPS treatment (P ≤ 0.05). At D1, the HH-LPS treatment increased splenic IL-6 mRNA and bursal IFNγ mRNA transcription while the SH-LPS treatment reduced splenic IL-6 mRNA compared with the SS-LPS treatment (P ≤ 0.05). The HH-LPS treatment reduced thymocyte proliferation efficiency, while at D1, D3, and D5, the SH-LPS treatment increased thymocyte proliferation efficiency compared with the SS-LPS treatment (P ≤ 0.05). Ducklings in the HH-LPS treatment had a higher splenic CD8+/CD4+ ratio compared to the SS-LPS treatment at D3 post-LPS injection (P ≤ 0.05). In summary, the HH-LPS treatment compromised immunocompetence via decreased NO production and thymocyte proliferation efficiency, while the SH-LPS treatment increased body weight and thymocyte proliferation and reduced IL-6 mRNA abundance. This suggests that an embryonic temperature stress during the latter half of incubation may prime the immune system which may be beneficial during secondary post-hatch inflammatory challenges.

Influence of incubation conditions on the formation of model biofilms by Listeria monocytogenes and Salmonella Typhimurium on abiotic surfaces

AIMS

This research aims to develop strongly adherent and mature model biofilms (on a 20 cm² polystyrene surface) for two pathogenic species, i.e. Listeria monocytogenes and Salmonella Typhimurium. These model biofilms can be used as standards to study biofilms or to study/compare the influence of different inactivation technologies.

METHODS AND RESULTS

Three influencing factors on the formation of biofilms are investigated, i.e. growth medium, incubation temperature and incubation time, which are three easily controllable environmental factors. Optical density measurement and plate counts were used to evaluate the adherence and the maturity of the biofilms, respectively. Confocal laser scanning microscopy was used to verify most important findings obtained with previously mentioned assays. Results indicated that mature and strongly adherent L. monocytogenes biofilms are obtained following 13 h of incubation at 30°C with BHI as growth medium. For S. Typhimurium, an incubation period of 19 h at 25°C was required with 20-fold diluted TSB as growth medium.

CONCLUSIONS

Based on previously mentioned assays, a protocol for the formation of reproducible model biofilms was obtained.

SIGNIFICANCE AND IMPACT OF THE STUDY

The developed model biofilms can be applied as a standard to study biofilms (in different research fields) and their subsequent inactivation by different methods. In addition, the results of this study could be used to control biofilm formation (e.g. by setting a maximum allowed surface temperature).

Incubation under climate warming affects learning ability and survival in hatchling lizards

Despite compelling evidence for substantial individual differences in cognitive performance, it is unclear whether cognitive ability influences fitness of wild animals. In many animals, environmental stressors experienced in utero can produce substantial variation in the cognitive abilities of offspring. In reptiles, incubation temperatures experienced by embryos can influence hatchling brain function and learning ability. Under climate warming, the eggs of some lizard species may experience higher temperatures, which could affect the cognitive abilities of hatchlings. Whether such changes in cognitive abilities influence the survival of hatchlings is unknown. To determine whether incubation-induced changes in spatial learning ability affect hatchling survival, we incubated velvet gecko, Amalosia lesueurii, eggs using two fluctuating temperature regimes to mimic current (cold) versus future (hot) nest temperatures. We measured the spatial learning ability of hatchlings from each treatment, and released individually marked animals at two field sites in southeastern Australia. Hatchlings from hot-incubated eggs were slower learners than hatchlings from cold-incubated eggs. Survival analyses revealed that hatchlings with higher learning scores had higher survival than hatchlings with poor learning scores. Our results show that incubation temperature affects spatial learning ability in hatchling lizards, and that such changes can influence the survival of hatchlings in the wild.

Habitat- and season-specific temperatures affect phenotypic development of hatchling lizards

Embryonic environments influence phenotypic development, but relatively few experiments have explored the effects of natural environmental variation. We incubated eggs of the lizard Anolis sagrei under conditions that mimicked natural spatial and temporal thermal variation to determine their effects on offspring morphology and performance. Incubation temperatures mimicked two microhabitats (open, shade) at two different times of the incubation season (April, July). Egg survival, incubation duration and offspring size were influenced by interactions between habitat- and season-specific nest temperatures, and locomotor performance was influenced primarily by temporal factors. These findings highlight the importance of spatial and temporal environmental variation in generating variation in fitness-related phenotypes.

Temperature alterations during embryogenesis have a sex-dependent influence on growth properties and muscle metabolism of day-old chicks and 35-day-old broilers

Broiler eggs were either incubated at 37.8°C during the whole incubation period (control), or at higher (38.8°C, group H) and lower temperatures (36.8°C, group L) from embryonic day (ED) 7 up to ED 10 (ED 7 to 10) or from ED 10 up to ED 13 (ED 10 to 13). Before and after this temperature treatment the eggs were incubated at 37.8°C. The day-old chicks were weighted, sexed and fed up to day 35. On days 1 and 35 samples were taken from the breast and leg muscles for analyzing of the mitochondrial respiratory activity (MRA) and from the breast muscles for analysis of the cross-sectional areas (CSA) and the glycogen phosphorylase (GP), phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome oxidase (COX) activities. Statistical analysis showed that treatment (control, group H, group L), sex and their interaction, but not the treatment period (ED 7 to 10; ED 10 to 13), significantly influenced the results. Group H chicks had lower (P⩽0.05) body and heart weights but higher (P⩽0.05) liver weights, CSA values, leg MRA as well as PFK, LDH, CS, GP and COX activities compared with the group L chicks. The results of the control chicks differ (P⩽0.05) from those of the group H (body, heart weight, COX), the group L chicks (liver weight, PFK, LDH, CS, GP) or the birds of both other groups (CSA). The group H broiler had higher (P⩽0.05) body and leg weights as well as LDH, CS, COX and GP activities than the group L broilers. The BWs and the LDH and GP results of the control broiler differ (P⩽0.05) from those of both other groups or from the results of the group H (CS) and group L broiler (COX). Female broilers had lower (P⩽0.05) body, breast and leg weights, but higher (P⩽0.05) CSA, LDH, CS and GP activities than the male animals. Analysis of treatment×sex interaction showed that group H hens had higher (P⩽0.05) body and breast weights, LDH and GP activities compared with the group L hens, whereas in the male broiler no effect of the interaction could be found, except for the lower (P⩽0.05) CSA values in the group H than group L cocks. The treatment effects are probably due to altered embryonic activity and related molecular mechanisms. The sex-related differences in the broiler indicate that these alterations already occur in the embryos and chicks, but become significant with the sexual dimorphism after hatch.

Is embryonic hypothermia tolerance common in birds?

Avian incubation temperatures oscillate within narrow limits to ensure proper embryonic development. However, field observations and experimental studies have found that some species can tolerate very low incubation temperatures, either regularly or occasionally. We artificially incubated eggs from five domestic species, which represent a range of egg sizes, to examine whether a diversity of avian species could exhibit an unusual hypothermia tolerance, as observed in the field. We found that eggs of the chicken (Gallus gallus domesticus), pigeon (Columba livia domestica), Japanese quail (Coturnix japonica) and budgerigar (Melopsittacus undulatus) survived the incubation period and hatched after experiencing 10°C hypothermia for 6 h each day. However, embryos of white-rumped munia (Lonchura striata) died after 10 days of hypothermia. Our results showed that unusual hypothermia tolerance occurs in several avian species. This phenomenon might have been selected through the evolutionary history of birds. Future research should identify the importance of phylogeny, egg size and embryonic stage in tolerance to hypothermia.

Temperature Effects on Development and Phenotype in a Free-Living Population of Western Pond Turtles (Emys marmorata)

Changes in temperature regimes are occurring globally due to climate change as well as habitat alterations. Temperatures are expected to continue to rise in the future, along with a greater degree of climatic instability. Such changes could have potentially serious consequences for oviparous ectotherms, especially those with temperature-dependent sex determination. To investigate the effects of temperature on a range of developmental phenomena in a population of western pond turtles (Emys marmorata), we placed temperature sensors on top of each layer of eggs within nests and recorded temperatures hourly through the first 2-3 mo of incubation. These methods allowed us to look at in situ nest temperatures with high resolution. We found that mean incubation temperatures were similar between different nests and at different levels within nests but that incubation temperature fluctuations and maximum incubation temperatures differed greatly in both cases. The hatchling turtles were more likely to be female if they spent 30% or more of their sex-determining period of incubation above 29°C. Hatching success was best predicted by the maximum incubation temperature. We also found that incubation duration tended to be shorter as the mean temperature increased. However, exposure to either extremely high or low temperatures extended incubation times.

Evidence in duck for supporting alteration of incubation temperature may have influence on methylation of genomic DNA

Incubation temperature has an immediate and long-term influence on the embryonic development in birds. DNA methylation as an important environment-induced mechanism could serve as a potential link between embryos’ phenotypic variability and temperature variation, which reprogrammed by DNA (cytosine-5)-methyltransferases (DNMTS) and Methyl-CpG binding domain proteins (MBPS) 3&5 (MBD3&5). Five genes in DNMTS and MBPS gene families were selected as target genes, given their important role in epigenetic modification. In this study, we aimed to test whether raising incubation temperature from 37.8°C to 38.8°C between embryonic days (ED) 1–10, ED10–20 and ED20–27 have effect on DNA methylation and whether DNMTS, MBPS play roles in thermal epigenetic regulation of early development in duck. Real-time quantitative PCR analysis showed that increased incubation temperature by 1°C has remarkably dynamic effect on gene expression levels of DNMTS and MBPS. Slight changes in incubation temperature significantly increased mRNA levels of target genes in breast muscle tissue during ED1–10, especially for DNMT1, DNMT3A and MBD5. In addition, higher temperature significantly increased enzyme activities of DNMT1 in leg muscle during ED10–20, liver tissue during ED1–10, ED20–27 and DNMT3A in leg muscle and breast muscle tissue during ED10–20. These results suggest that incubation temperature has an extended effect on gene expression levels and enzyme activities of DNMTS and MBPS, which provides evidence that incubation temperature may influence DNA methylation in duck during early developmental stages. Our data indicated that DNMTS and MBPS may involved in thermal epigenetice regulation of embryos during the early development in duck. The potential links between embryonic temperature and epigenetic modification need further investigation

Strain- and temperature-dependent changes of fatty acid composition in Wickerhamomyces anomalus and Blastobotrys adeninivorans

The fatty acid (FA) profiles of two strains of the yeasts Wickerhamomyces anomalus and Blastobotrys (Arxula) adeninivorans at cultivation temperatures from 15 to 30 °C were characterized. Besides the common even-numbered C16 and C18 FAs, substantial proportions of the uneven-numbered C17:1 were found in both species. C18:3(n-3) (alpha linolenic acid) made up to 3% of the total FAs in all strains. Considerable strain differences occurred, with regard to both the presence of single FAs and parameters like the double binding index (DBI) and C16:C18 ratio. W. anomalus J121 formed C18:1(n-5) (up to 10.9% of the total FAs) but no C18:1(n-7), whereas in W. anomalus VKM160, no C18:1(n-5) was found but up to 14.6% C18:1(n-7). Similarly, B. adeninivorans CBS 8244 formed exclusively C18:1(n-7) (maximum 9%) and CBS 7377 C18:1(n-5) (maximum 12.6%). W. anomalus J121 had the lowest DBI (0.72) at 15 °C and the highest (0.92) at 20 °C, at which point the values decreased with increasing temperatures. In W. anomalus VKM160 and both B. adeninivorans strains, DBI was highest at 15 °C and decreased with increasing temperature. In J121, the C16:C18 ratio was highest at 15 °C, decreasing at higher temperatures, whereas in the other strains, the opposite trend was observed.

A modified method for consistent and reliable Golgi-cox staining in significantly reduced time

The two major limitations of Golgi–Cox method are that staining takes very long time and it is inconsistent. In this paper we describe a modification of the Golgi–Cox method, in which the tissue blocks were maintained at 37 ± 1°C during chromation for only 24 h and consistent staining of neurons in rat brain sections were observed. The method is simple, reproducible, rapid, inexpensive, and provides uniform staining with very good resolution of neuronal soma, dendrites as well as spines.

Effects of a warmer climate on seed germination in the subarctic

BACKGROUND AND AIMS

In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined.

METHODS

Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year.

KEY RESULTS

Moderate summer warming (+2.5 degrees C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10 degrees C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate.

CONCLUSIONS

Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.

An investigation of the replication of coronaviruses in suspension cultures of L132 cells

A system is described for the study of the multiplication of two coronaviruses, both of human origin. Low efficiences of adsorption and infectious centre formation were observed. The viruses were found to have a 4–6 hour eclipse phase in L 132 cells at 33° C. Both viruses were completely inhibited by raising the incubation temperature to 39° C, and there was also a depression in the yield of virus at 30° C compared with control cultures maintained at 33° C. “Shift” experiments have indicated that the high temperature-sensitive event occurred fairly late on in the replicative cycle, but the time could not be accurately determined.