Nucleocytoplasmic shuttling of BEFV M protein-modulated by lamin A/C and chromosome maintenance region 1 through a transcription-, carrier- and energy-dependent pathway

This study demonstrates for the first time that the matrix (M) protein of BEFV is a nuclear targeting protein that shuttles between the nucleus and the cytoplasm in a transcription-, carrier-, and energy-dependent manner. Experiments performed in both intact cells and digitonin-permeabilized cells revealed that M protein targets the nucleolus and requires carrier, cytosolic factors or energy input. By employing sequence and mutagenesis analyses, we have determined both nuclear localization signal (NLS) 6KKGKSK11 and nuclear export signal (NES) 98LIITSYL TI106 of M protein that are important for the nucleocytoplasmic shuttling of M protein. Furthermore, we found that both lamin A/C and chromosome maintenance region 1 (CRM-1) proteins could be coimmunoprecipitated and colocalized with the BEFV M protein. Knockdown of lamin A/C by shRNA and inhibition of CRM-1 by leptomycin B significantly reduced virus yield. Collectively, this study provides novel insights into nucleocytoplasmic shuttling of the BEFV M protein modulated by lamin A/C and CRM-1 and by a transcription- and carrier- and energy-dependent pathway.

Halophilic Plant-Associated Bacteria with Plant-Growth-Promoting Potential

The salinization of soils is a growing agricultural concern worldwide. Irrigation practices, drought, and climate change are leading to elevated salinity levels in many regions, resulting in reduced crop yields. However, there is potential for a solution in the microbiome of halophytes, which are naturally salt-tolerant plants. These plants harbor a salt-tolerant microbiome in their rhizosphere (around roots) and endosphere (within plant tissue). These bacteria may play a significant role in conferring salt tolerance to the host plants. This leads to the possibility of transferring these beneficial bacteria, known as salt-tolerant plant-growth-promoting bacteria (ST-PGPB), to salt-sensitive plants, enabling them to grow in salt-affected areas to improve crop productivity. In this review, the background of salt-tolerant microbiomes is discussed and their potential use as ST-PGPB inocula is explored. We focus on two Gram-negative bacterial genera, Halomonas and Kushneria, which are commonly found in highly saline environments. These genera have been found to be associated with some halophytes, suggesting their potential for facilitating ST-PGPB activity. The study of salt-tolerant microbiomes and their use as PGPB holds promise for addressing the challenges posed by soil salinity in the context of efforts to improve crop growth in salt-affected areas.

Salt-Induced Modulation of Ion Transport and PSII Photoprotection Determine the Salinity Tolerance of Amphidiploid Brassicas

Brassica species show varying levels of resistance to salt stress. To understand the genetics underlying these differential stress tolerance patterns in Brassicas, we exposed two widely cultivated amphidiploid Brassica species having different genomes, Brassica juncea (AABB, n = 18) and Brassica napus (AACC, n = 19), to elevated levels of NaCl concentration (300 mM, half the salinity of seawater). B. juncea produced more biomass, an increased chlorophyll content, and fewer accumulated sodium (Na+) and chloride (Cl-) ions in its photosynthesizing tissues. Chlorophyll fluorescence assays revealed that the reaction centers of PSII of B. juncea were more photoprotected and hence more active than those of B. napus under NaCl stress, which, in turn, resulted in a better PSII quantum efficiency, better utilization of photochemical energy with significantly reduced energy loss, and higher electron transport rates, even under stressful conditions. The expression of key genes responsible for salt tolerance (NHX1 and AVP1, which are nuclear-encoded) and photosynthesis (psbA, psaA, petB, and rbcL, which are chloroplast-encoded) were monitored for their genetic differences underlying stress tolerance. Under NaCl stress, the expression of NHX1, D1, and Rubisco increased several folds in B. juncea plants compared to B. napus, highlighting differences in genetics between these two Brassicas. The higher photosynthetic potential under stress suggests that B. juncea is a promising candidate for genetic modifications and its cultivation on marginal lands.

Cell Entry of Avian Reovirus Modulated by Cell-Surface Annexin A2 and Adhesion G Protein-Coupled Receptor Latrophilin-2 Triggers Src and p38 MAPK Signaling Enhancing Caveolin-1- and Dynamin 2-Dependent Endocytosis

The specifics of cell receptor-modulated avian reovirus (ARV) entry remain unknown. By using a viral overlay protein-binding assay (VOPBA) and an in-gel digestion coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS), we determined that cell-surface annexin A2 (AnxA2) and adhesion G protein-coupled receptor Latrophilin-2 (ADGRL2) modulate ARV entry. Direct interaction between the ARV σC protein and AnxA2 and ADGRL2 in Vero and DF-1 cells was demonstrated in situ by proximity ligation assays. By using short hairpin RNAs (shRNAs) to silence the endogenous AnxA2 and ADGRL2 genes, ARV entry could be efficiently blocked. A significant decrease in virus yields and the intracellular specific signal for σC protein was observed in Vero cells preincubated with the specific AnxA2 and ADGRL2 monoclonal antibodies, indicating that AnxA2 and ADGRL2 are involved in modulating ARV entry. Furthermore, we found that cells pretreated with the AnxA2/S100A10 heterotetramer (A2t) inhibitor A2ti-1 suppressed ARV-mediated activation of Src and p38 mitogen-activated protein kinase (MAPK), demonstrating that Src and p38 MAPK serve as downstream molecules of cell-surface AnxA2 signaling. Our results reveal that suppression of cell-surface AnxA2 with the A2ti-1 inhibitor increased Csk-Cbp interaction, suggesting that ARV entry suppresses Cbp-mediated relocation of Csk to the membrane, thereby activating Src. Furthermore, reciprocal coimmunoprecipitation assays revealed that σC can interact with signaling molecules, lipid raft, and vimentin. The current study provides novel insights into cell-surface AnxA2- and ADGRL2-modulated cell entry of ARV which triggers Src and p38 MAPK signaling to enhance caveolin-1-, dynamin 2-, and lipid raft-dependent endocytosis. IMPORTANCE By analyzing results from VOPBA and LC-MS/MS, we have determined that cell-surface AnxA2 and ADGRL2 modulate ARV entry. After ARV binding to receptors, Src and p38 MAPK signaling were triggered and, in turn, increased the phosphorylation of caveolin-1 (Tyr14) and upregulated dynamin 2 expression to facilitate caveolin-1-mediated and dynamin 2-dependent endocytosis. In this work, we demonstrated that ARV triggers Src activation by impeding Cbp-mediated relocation of Csk to the membrane in the early stages of the life cycle. This work provides better insight into cell-surface AnxA2 and ADGRL2, which upregulate Src and p38MAPK signaling pathways to enhance ARV entry and productive infection.

Impact of Nanomaterials on the Regulation of Gene Expression and Metabolomics of Plants under Salt Stress

Plant salinity resistance results from a combination of responses at the physiological, molecular, cellular, and metabolic levels. This article focuses on plant stress tolerance mechanisms for controlling ion homeostasis, stress signaling, hormone metabolism, anti-oxidative enzymes, and osmotic balance after nanoparticle applications. Nanoparticles are used as an emerging tool to stimulate specific biochemical reactions related to plant ecophysiological output because of their small size, increased surface area and absorption rate, efficient catalysis of reactions, and adequate reactive sites. Regulated ecophysiological control in saline environments could play a crucial role in plant growth promotion and survival of plants under suboptimal conditions. Plant biologists are seeking to develop a broad profile of genes and proteins that contribute to plant salt resistance. These plant metabolic profiles can be developed due to advancements in genomic, proteomic, metabolomic, and transcriptomic techniques. In order to quantify plant stress responses, transmembrane ion transport, sensors and receptors in signaling transduction, and metabolites involved in the energy supply require thorough study. In addition, more research is needed on the plant salinity stress response based on molecular interactions in response to nanoparticle treatment. The application of nanoparticles as an aspect of genetic engineering for the generation of salt-tolerant plants is a promising area of research. This review article addresses the use of nanoparticles in plant breeding and genetic engineering techniques to develop salt-tolerant crops.

Molecular chaperone TRiC governs avian reovirus replication by protecting outer-capsid protein σC and inner core protein σA and non-structural protein σNS from ubiquitin- proteasome degradation

Avian reoviruses (ARVs) are important pathogens that cause considerable economic losses in poultry farming. To date, host factors that control stabilization of ARV proteins remain largely unknown. In this work we determined that the eukaryotic chaperonin T-complex protein-1 (TCP-1) ring complex (TRiC) is essential for avian reovirus (ARV) replication by stabilizing outer-capsid protein σC, inner core protein σA, and the non-structural protein σNS of ARV. TriC serves as a chaperone of viral proteins and prevent their degradation via the ubiquitin-proteasome pathway. Furthermore, reciprocal co-immunoprecipitation assays confirmed the association of viral proteins (σA, σC, and σNS) with TRiC. Immunofluorescence staining indicated that the TRiC chaperonins (CCT2 and CCT5) are colocalized with viral proteins σC, σA, and σNS of ARV. In this study, inhibition of TRiC chaperonins (CCT2 and CCT5) by the inhibitor HSF1A or shRNAs significantly reduced expression levels of the σC, σA, and σNS proteins of ARV as well as virus yield, suggesting that the TRiC complex functions in stabilization of viral proteins and virus replication. This study provides novel insights into TRiC chaperonin governing virus replication via stabilization of outer-capsid protein σC, inner core protein σA, and the non-structural protein σNS of ARV.

Editing the plastid genome of recalcitrant plant species

Transformation of the chloroplast genome offers key advantages over traditional methods for generating transgenic plants, but this approach is limited to a few plant species. Nakazato et al. have developed a novel technique that will help to extend the technology to other plant species that are recalcitrant to current tissue culture-based chloroplast transformation protocols.

Effects of Salinity Stress on Chloroplast Structure and Function

Salinity is a growing problem affecting soils and agriculture in many parts of the world. The presence of salt in plant cells disrupts many basic metabolic processes, contributing to severe negative effects on plant development and growth. This review focuses on the effects of salinity on chloroplasts, including the structures and function of these organelles. Chloroplasts house various important biochemical reactions, including photosynthesis, most of which are considered essential for plant survival. Salinity can affect these reactions in a number of ways, for example, by changing the chloroplast size, number, lamellar organization, lipid and starch accumulation, and interfering with cross-membrane transportation. Research has shown that maintenance of the normal chloroplast physiology is necessary for the survival of the entire plant. Many plant species have evolved different mechanisms to withstand the harmful effects of salt-induced toxicity on their chloroplasts and its machinery. The differences depend on the plant species and growth stage and can be quite different between salt-sensitive (glycophyte) and salt-tolerant (halophyte) plants. Salt stress tolerance is a complex trait, and many aspects of salt tolerance in plants are not entirely clear yet. In this review, we discuss the different mechanisms of salt stress tolerance in plants with a special focus on chloroplast structure and its functions, including the underlying differences between glycophytes and halophytes.

Dairy goats adjust their meal patterns to the fibre content of the diet

Few studies have investigated how meal patterns of ruminants are affected by diet fibre content. Dairy goats (N = 32) in late lactation and early gestation were housed in eight groups of four goats, with all combinations of breed (Alpine and Saanen) and lactation number (1 and 2) represented in each group. Each goat had access to its own individual feed trough placed on a weigh scale with data logged automatically. All goats were fed the same total mixed ration (TMR; 30% concentrate and 44.6% NDF in DM) ad libitum for a control period of 22 days. Using the same feed ingredients, half of the groups were then offered a High fibre diet (20% concentrate; 47.3% NDF), and the other half a Low fibre diet (40% concentrate; 41.5% NDF) for a treatment period of 16 days. Daily meal patterns (meal frequency, duration and size, feeding rate, daily feed intake and daily feeding time) were computed for each animal using a meal criterion of 8 min. The last 10 days for each period (control and treatment) were used to calculate individual period means and individual differences between the two periods. During the control period, the goats ate on average 12.1 ± 0.49 meals/day, consuming 4.2 ± 0.10 kg fresh TMR daily. When the ration changed, all measures of feeding behaviour except meal size changed asymmetrically for the goats on the two diets. Goats fed the High fibre diet reduced their meal frequency by 10%, and the first meal after feed distribution lasted 11% longer, leading to a 9% reduction in feeding rate and no significant changes in daily feed intake and daily feeding time. Goats on the Low fibre diet did not significantly change their meal frequency or meal size, but the combined changes nevertheless led to a 9% increase in daily feed intake. On the Low fibre diet, goats were able to increase their feeding rate by a third, leading to a reduction in meal durations, thus reducing daily feeding time by 13%. Goats adapt their feeding behaviour to the fibre proportion of the offered diet, with more changes when fibre content is lowered, which needs to be taken into account when comparing phenotypes and adaptability of small ruminants to different diets.

Plastid Transcriptomics: An Important Tool For Plastid Functional Genomics

Plastids in higher plants carry out specialized roles such as photosynthesis, nitrogen assimilation, biosynthesis of amino acids, fatty acids, isoprenoids, and various metabolites. Plastids arise from undifferentiated precursors known as proplastids, which are found in the root and shoot meristems. They are highly dynamic as they change their number, morphology, and physiology according to the tissue they are present. In addition to housing various metabolic activities, plastids also serve as a global sensor for both internal and external environmental cues including different stresses, and help plants to respond/adjust accordingly. They relay information to the nucleus, which then responds by changing the expression levels of specific genes. It has been shown that plants with impaired plastid functions exhibit abnormalities. One of the sources emanating these signals to the nucleus is plastid transcription. Normal plastid functioning is therefore critical for plant survival. Despite immense significance for plant acclimation, the plastid transcriptome is largely an unstudied research area. In this review, we discuss the importance of plastid transcriptomics for the acclimation of plants under changing environmental conditions and summarize the key literature published in this field.

Aspirin and 5-Aminoimidazole-4-carboxamide Riboside Attenuate Bovine Ephemeral Fever Virus Replication by Inhibiting BEFV-Induced Autophagy

Recent study in our laboratory has demonstrated that BEFV-induced autophagy via activation of the PI3K/Akt/NF-κB and Src/JNK pathways and suppression of the PI3K-AKt-mTORC1 pathway is beneficial for virus replication. In the current study, we found that both aspirin and 5-aminoimidazole-4-carboxamide-1-β-riboside (AICAR) siginificantly attenuated virus replication by inhibiting BEFV-induced autophagy via suppressing the BEFV-activated PI3K/Akt/NF-κB and Src/JNK pathways as well as inducing reversion of the BEFV-suppressed PI3K-Akt-mTORC1 pathway. AICAR reversed the BEFV-activated PI3K/Akt/NF-κB and Src/JNK pathways at the early to late stages of infection and induced reversion of the BEFV-suppressed PI3K-AKt-mTORC1 pathway at the late stage of infection. Our findings reveal that inhibition of BEFV-induced autophagy by AICAR is independent of AMPK. Furthermore, we found that AICAR transcriptionally downregulates the ATG related genes ULK1, Beclin 1, and LC3 and enhances Atg7 degradation by the proteasome pathway. Aspirin suppresses virus replication by inhibiting BEFV-induced autophagy. It directly suppressed the NF-κB pathway and reversed the BEFV-activated Src/JNK pathway at the early stage of infection and reversed the BEFV-suppressed PI3K/Akt/mTOR pathway at the late stage of infection. The current study provides mechanistic insights into the effects of aspirin and AICAR on BEFV replication through suppression of BEFV-induced autophagy.

Construction of polycistronic baculovirus surface display vectors to express the PCV2 Cap(d41) protein and analysis of its immunogenicity in mice and swine

To increase expression levels of the PCV2 Cap(d41) protein, novel baculovirus surface display vectors with multiple expression cassettes were constructed to create recombinant baculoviruses BacSC-Cap(d41), BacDD-2Cap(d41), BacDD-3Cap(d41), and BacDD-4Cap(d41). Our results reveal that the recombinant baculovirus BacDD-4Cap(d41) was able to express the highest levels of Cap(d41) protein. Optimum conditions for expressing the PCV2 Cap(d41) protein were determined, and our results show that 107 of Sf-9 infected with the recombinant baculovirus BacDD-4Cap(d41) at an MOI of 5 for 3 days showed the highest level of protein expression. Mice immunized with the 4Cap(d41) vaccine which was prepared from the recombinant baculovirus-infected cells (107) elicited higher ELISA titers compared to the Cap (d41) vaccine. The 4Cap(d41) vaccine could elicit anti-PCV2 neutralizing antibodies and IFN-γ in mice, as confirmed by virus neutralization test and IFN-γ ELISA. Moreover, the swine lymphocyte proliferative responses indicated that the 4Cap(d41) vaccine was able to induce a clear cellular immune response. Flow cytometry analysis showed that the percentage of CD4+ T cells and CD4+/CD8+ ratio was increased significantly in SPF pigs immunized with the 4Cap(d41) vaccine. Importantly, the 4Cap(d41) vaccine induced an IFN-γ response, further confirming that its effect is through cellular immunity in SPF pigs. An in vivo challenge study revealed that the 4Cap(d41) and the commercial vaccine groups significantly reduce the viral load of vaccinated pigs as compared with the CE negative control group. Taken together, we have successfully developed a 4Cap(d41) vaccine that may be a potential subunit vaccine for preventing the disease associated with PCV2 infections.

Baculovirus surface display of the HA protein of H5N2 avian influenza virus and its immunogenicity against a lethal challenge with H5N1 virus in chickens

In the present study, we have generated several H5N2 HA recombinant baculoviruses for production of a HA subunit vaccine against the lethal H5N2 avian influenza virus (AIV). The effective display of functional HA on the cell membrane and baculoviral envelope was examined. Our results reveal that chickens immunized with the chimeric AIV HA protein fused with the baculovirus gp64 cytoplasmic domain (CTD) induced higher HI titer. To further increase the expression level of the H5N2 AIV HA protein, the HA gene of H5N2 AIV was amplified and cloned into three novel baculovirus surface display vectors BacDual DisplayEGFP-2HA, BacDual DisplayEGFP-3HA, BacDual DisplayEGFP-4HA which contains multiple expression cassettes for higher level display of HA proteins on the cell membrane and baculovirus envelope. To determine the optimum conditions for producing HA protein, various MOI, infection times, and shaker times for virus transfection were tested. Our results reveal that the conditions of an MOI of 5, 3 day post infection, and 15 min of shaker time have higher efficiency for HA protein production. Our results reveal that the baculovirus surface display vector pBacDual DisplayEGFP-4HA increases significantly the expression level of the H5N2 AIV HA protein. Chickens that received two doses of BacDual DisplayEGFP-4HA cell lysates formulated with Montanide ISA70 adjuvant elicited efficient immunogenicity and had an average HI titer of 7 log₂ at 2 weeks post-vaccination. Challenge studies revealed that vaccinated chickens with HI titers 5 log₂ were completely protected against the lethal H5N1 AIV challenge. Furthermore, HI titers could be maintained at 5 log₂ for 20 weeks for laying hens. This study suggests that the HA protein expression from the baculovirus surface display system could be a safe and efficacious subunit vaccine for chickens.

Salt induced modulations in antioxidative defense system of Desmostachya bipinnata

This study addressed the interactions between salt stress and the antioxidant responses of a halophytic grass, Desmostachya bipinnata. Plants were grown in a semi-hydroponic system and treated with different NaCl concentrations (0 mM, 100 mM, 400 mM) for a month. ROS degradation enzyme activities were stimulated by addition of NaCl. Synthesis of antioxidant compounds, such as phenols, was enhanced in the presence of NaCl leading to accumulation of these compounds under moderate salinity. However, when the ROS production rate exceeded the capacity of enzyme-controlled degradation, antioxidant compounds were consumed and oxidative damage was indicated by significant levels of hydrogen peroxide at high salinity. The cellular concentration of salicylic acid increased upon salt stress, but since no direct interaction with ROS was detected, a messenger function may be postulated. High salinity treatment caused a significant decrease of plant growth parameters, whereas treatment with moderate salinity resulted in optimal growth. The activity and abundance of superoxide dismutase (SOD) increased with salinity, but the abundance of SOD isoforms was differentially affected, depending on the NaCl concentration applied. Detoxification of hydrogen peroxide (H₂O₂) was executed by catalase and guaiacol peroxidase at moderate salinity, whereas the enzymes detoxifying H₂O₂ through the ascorbate/glutathione cycle dominated at high salinity. The redox status of glutathione was impaired at moderate salinity, whereas the levels of both ascorbate and glutathione significantly decreased only at high salinity. Apparently, the maximal activation of enzyme-controlled ROS degradation was insufficient in comparison to the ROS production at high salinity. As a result, ROS-induced damage could not be prevented, if the applied stress exceeded a critical value in D. bipinnata plants.

Bovine ephemeral fever virus triggers autophagy enhancing virus replication via upregulation of the Src/JNK/AP1 and PI3K/Akt/NF-κB pathways and suppression of the PI3K/Akt/mTOR pathway

Autophagy plays an important role in cellular response to pathogens. However, the impact of the autophagy machinery on bovine ephemeral fever virus (BEFV) infection is not yet determined. A recent study in our laboratory demonstrated that BEFV triggers simultaneously the PI3K/Akt/NF-κB and Src/JNK-AP1 pathways in the stage of virus binding to enhance virus entry. In this work, we report that BEFV induces autophagy via upregulation of the PI3K/Akt/NF-κB and Src/JNK/AP1 pathways in the early to middle stages of infection and suppresses the PI3K/Akt/mTOR pathway at the late stage of infection. To activate NF-κB, BEFV promotes degradation of IκBα and activates Akt to stimulate NF-κB translocation into the nucleus. Immunoprecipitation assays revealed that BEFV disrupts Beclin 1 and Bcl-2 interaction by JNK-mediated Bcl-2 phosphorylation, thereby activating autophagy. Overexpression of Bcl-2 reversed the BEFV-induced increase in the LC3 II levels. Suppression of autophagy either by knockdown of autophagy-related genes with shRNAs or treatment with a pharmacological inhibitor 3-MA reduced BEFV replication, suggesting that BEFV-induced autophagy benefits virus replication. Our results revealed that the BEFV M protein is one of the viral proteins involved in inducing autophagy via suppression of the PI3K/Akt/mTORC1 pathway. Furthermore, degradation of p62 was observed by immunoblotting, suggesting that BEFV infection triggers a complete autophagic response. Disruption of autophagosome-lysosome fusion by depleting LAMP2 resulted in reduction of virus yield, suggesting that formation of autolysosome benefits virus production.

Identification and evolutionary characterization of salt-responsive transcription factors in the succulent halophyte Suaeda fruticosa

Transcription factors are key regulatory elements that affect gene expression in response to specific signals, including environmental stresses such as salinity. Halophytes are specialized plants that have the ability to complete their life cycle in saline environments. In this study we have identified and characterized the evolutionary relationships of putative transcription factors (TF) in an obligate succulent halophyte, Suaeda fruticosa, that are involved in conferring salt tolerance. Using RNA-seq data we have analyzed the expression patterns of certain TF families, predicted protein-protein interactions, and analyzed evolutionary trajectories to elucidate their possible roles in salt tolerance. We have detected the top differentially expressed (DE) transcription factor families (MYB, CAMTA, MADS-box and bZIP) that show the most pronounced response to salinity. The majority of DE genes in the four aforementioned TF families cluster together on TF phylogenetic trees, which suggests common evolutionary origins and trajectories. This research represents the first comprehensive TF study of a leaf succulent halophyte including their evolutionary relationships with TFs in other halophyte and salt-senstive plants. These findings provide a foundation for understanding the function of salt-responsive transcription factors in salt tolerance and associated gene regulation in plants.

Salt-Tolerant Halophyte Rhizosphere Bacteria Stimulate Growth of Alfalfa in Salty Soil

Halophytes are plants that are adapted to grow in saline soils, and have been widely studied for their physiological and molecular characteristics, but little is known about their associated microbiomes. Bacteria were isolated from the rhizosphere and as root endophytes of Salicornia rubra, Sarcocornia utahensis, and Allenrolfea occidentalis, three native Utah halophytes. A total of 41 independent isolates were identified by 16S rRNA gene sequencing analysis. Isolates were tested for maximum salt tolerance, and some were able to grow in the presence of up to 4 M NaCl. Pigmentation, Gram stain characteristics, optimal temperature for growth, and biofilm formation of each isolate aided in species identification. Some variation in the bacterial population was observed in samples collected at different times of the year, while most of the genera were present regardless of the sampling time. Halomonas, Bacillus, and Kushneria species were consistently isolated both from the soil and as endophytes from roots of all three plant species at all collection times. Non-culturable bacterial species were analyzed by Illumina DNA sequencing. The most commonly identified bacteria were from several phyla commonly found in soil or extreme environments: Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, and Gamma- and Delta-Proteobacteria. Isolates were tested for the ability to stimulate growth of alfalfa under saline conditions. This screening led to the identification of one Halomonas and one Bacillus isolate that, when used to inoculate young alfalfa seedlings, stimulate plant growth in the presence of 1% NaCl, a level that significantly inhibits growth of uninoculated plants. The same bacteria used in the inoculation were recovered from surface sterilized alfalfa roots, indicating the ability of the inoculum to become established as an endophyte. The results with these isolates have exciting promise for enhancing the growth of inoculated alfalfa in salty soil.

Arabidopsis thaliana organelles mimic the T7 phage DNA replisome with specific interactions between Twinkle protein and DNA polymerases Pol1A and Pol1B

BACKGROUND

Plant chloroplasts and mitochondria utilize nuclear encoded proteins to replicate their DNA. These proteins are purposely built for replication in the organelle environment and are distinct from those involved in replication of the nuclear genome. These organelle-localized proteins have ancestral roots in bacterial and bacteriophage genes, supporting the endosymbiotic theory of their origin. We examined the interactions between three of these proteins from Arabidopsis thaliana: a DNA helicase-primase similar to bacteriophage T7 gp4 protein and animal mitochondrial Twinkle, and two DNA polymerases, Pol1A and Pol1B. We used a three-pronged approach to analyze the interactions, including Yeast-two-hybrid analysis, Direct Coupling Analysis (DCA), and thermophoresis.

RESULTS

Yeast-two-hybrid analysis reveals residues 120-295 of Twinkle as the minimal region that can still interact with Pol1A or Pol1B. This region is a part of the primase domain of the protein and slightly overlaps the zinc-finger and RNA polymerase subdomains located within. Additionally, we observed that Arabidopsis Twinkle interacts much more strongly with Pol1A versus Pol1B. Thermophoresis also confirms that the primase domain of Twinkle has higher binding affinity than any other region of the protein. Direct-Coupling-Analysis identified specific residues in Twinkle and the DNA polymerases critical to positive interaction between the two proteins.

CONCLUSIONS

The interaction of Twinkle with Pol1A or Pol1B mimics the minimal DNA replisomes of T7 phage and those present in mammalian mitochondria. However, while T7 and mammals absolutely require their homolog of Twinkle DNA helicase-primase, Arabidopsis Twinkle mutants are seemingly unaffected by this loss. This implies that while Arabidopsis mitochondria mimic minimal replisomes from T7 and mammalian mitochondria, there is an extra level of redundancy specific to loss of Twinkle function.

Avian reovirus σA-modulated suppression of lactate dehydrogenase and upregulation of glutaminolysis and the mTOC1/eIF4E/HIF-1α pathway to enhance glycolysis and the TCA cycle for virus replication

Adenosine triphosphate (ATP) is an energy source for many types of viruses for facilitating virus replication. This is the first report to demonstrate that the structural protein σA of avian reovirus (ARV) functions as an activator of cellular energy. Three cellular factors, isocitrate dehydrogenase 3 subunit beta (IDH3B), lactate dehydrogenase A (LDHA), and vacuolar-type H+-ATPase (vATPase) co-immunoprecipitated with ARV σA and were identified by 2D-LC/MS/MS. ARV enhances glycolytic flux through upregulation of glycolytic enzymes. Increased ATP levels in both ARV-infected and σA-transfected cells were observed by a fluorescence resonance energy transfer-based genetically encoded indicator, Ateams. Furthermore, σA upregulates IDH3B and glutamate dehydrogenase (GDH) to promote glutaminolysis, activating HIF-1α. Both HIF-1α level and viral yield in IDH3B-depleted and glutamine-deprived cells, and inhibition of glutaminolysis was significantly reduced. The σA_R155/273A mutant loses its ability to enter the nucleolus, impairing its ability to regulate glycolysis. In addition, we have identified the conserved untranslated regions (UTR) of the 5'- and 3'-termini of the ARV genome segments that are required for viral protein synthesis in an ATP-dependent manner. Deletion of either the 5'- or 3'-UTR impaired viral protein synthesis. Knockdown of σA reduced the ATP level and significantly decreased virus yield, suggesting that σA enhances ATP formation to promote virus replication. Collectively, this study provides novel insights into σA-modulated suppression of LDHA and activation of IDH3B and GDH to activate the mTORC1/eIF4E/HIF-1α pathways to upregulate glycolysis and the TCA cycle for virus replication.

Differential protein expression reveals salt tolerance mechanisms of Desmostachya bipinnata at moderate and high levels of salinity

A proteomics approach was used to investigate salt tolerance mechanisms of Desmostachya bipinnata (L.) Stapf. Plants were subjected to 0mM (control), 100mM (moderate) and 400mM (high) NaCl. Proteins were separated by two-dimensional gel electrophoresis and identified with available databases. Optimal plant fresh weight was found at moderate salinity but declined at high salinity. Water potential, osmotic potential, Na+/K+ ratio, leaf electrolyte leakage, sugars and proline were altered at high salinity. However, water potential, proline content and electrolyte leakage were maintained at moderate salinity; Na+ and K+ concentrations increased, whereas sugars and osmotic potential decreased. Comparative proteome analysis revealed 103 salt responsive proteins. At moderate salinity, most of the proteins involved in energy metabolism, transport, antioxidative defence and cell growth were either unchanged or increased. Proteins related to amino-acid metabolism were decreased while those associated with secondary metabolism were accumulated. At high salinity, amino-acid metabolism and dehydration responses were evident; proteins of energy metabolism, transport and stress defence were downregulated. These results suggest that an efficient defence system, improved transport of water and metabolites, increased cell wall lignification and regulation of energy and carbohydrate metabolism allowed better potential for plant growth under moderately saline conditions.

Mechanistic insights into avian reovirus p17-modulated suppression of cell cycle CDK-cyclin complexes and enhancement of p53 and cyclin H interaction

The avian reovirus p17 protein is a nucleocytoplasmic shuttling protein. Although we have demonstrated that p17 causes cell growth retardation via activation of p53, the precise mechanisms remain unclear. This is the first report that avian reovirus p17 possesses broad inhibitory effects on cell cycle CDKs, cyclins, CDK-cyclin complexes, and CDK-activating kinase activity in various mammalian, avian, and cancer cell lines. Suppression of CDK activity by p17 occurs by direct binding to CDKs, cyclins, and CDK-cyclin complexes; transcriptional down-regulation of CDKs; cytoplasmic retention of CDKs and cyclins; and inhibition of CDK-activating kinase activity by promoting p53-cyclin H interaction. p17 binds to CDK-cyclin except for CDK1-cyclin B1 and CDK7-cyclin H complexes. We have determined that the negatively charged ¹⁵¹LAVXDVDA(E/D)DGADPN¹⁶⁵ motif in cyclin B1 interacts with a positively charged region of CDK1. p17 mimics the cyclin B1 sequence to compete for CDK1 binding. The PSTAIRE motif is not required for interaction of CDK1-cyclin B1, but it is required for other CDK-cyclin complexes. p17 interacts with cyclins by its cyclin-binding motif, ¹²⁵RXL¹²⁷ Sequence and mutagenic analyses of p17 indicated that a ¹⁴⁰WXFD¹⁴³ motif and residues Asp-113 and Lys-122 in p17 are critical for CDK2 and CDK6 binding, leading to their sequestration in the cytoplasm. Exogenous expression of p17 significantly enhanced virus replication, whereas p17 mutants with low binding ability to cell cycle CDKs had no effect on virus yield, suggesting that p17 inhibits cell growth and the cell cycle, benefiting virus replication. An in vivo tumorigenesis assay also showed a significant reduction in tumor size.

Personal microbiome analysis improves student engagement and interest in Immunology, Molecular Biology, and Genomics undergraduate courses

A critical area of emphasis for science educators is the identification of effective means of teaching and engaging undergraduate students. Personal microbiome analysis is a means of identifying the microbial communities found on or in our body. We hypothesized the use of personal microbiome analysis in the classroom could improve science education by making courses more applied and engaging for undergraduate students. We determined to test this prediction in three Brigham Young University undergraduate courses: Immunology, Advanced Molecular Biology Laboratory, and Genomics. These three courses have a two-week microbiome unit and students during the 2016 semester students could submit their own personal microbiome kit or use the demo data, whereas during the 2017 semester students were given access to microbiome data from an anonymous individual. The students were surveyed before, during, and after the human microbiome unit to determine whether analyzing their own personal microbiome data, compared to analyzing demo microbiome data, impacted student engagement and interest. We found that personal microbiome analysis significantly enhanced the engagement and interest of students while completing microbiome assignments, the self-reported time students spent researching the microbiome during the two week microbiome unit, and the attitudes of students regarding the course overall. Thus, we found that integrating personal microbiome analysis in the classroom was a powerful means of improving student engagement and interest in undergraduate science courses.

Avian reovirus p17 and σA act cooperatively to downregulate Akt by suppressing mTORC2 and CDK2/cyclin A2 and upregulating proteasome PSMB6

Although we have shown that avian reovirus (ARV) p17-mediated inhibition of Akt leads to induction of autophagy, the precise mechanisms remain largely unknown. This study has identified a specific mechanism by which ARV coordinately regulates the degradation of ribosomal proteins by p17-mediated activation of E3 ligase MDM2 that targets ribosomal proteins and by σA-mediated upregulation of proteasome PSMB6. In addition to downregulating ribosomal proteins, p17 reduces mTORC2 assembly and disrupts mTORC2-robosome association, both of which inactivate mTORC2 leading to inhibition of Akt phosphorylation at S473. Furthermore, we discovered that p17 binds to and inhibits the CDK2/cyclin A2 complex, further inhibiting phosphorylation of Akt S473. The negative effect of p17 on mTORC2 assembly and Akt phosphorylation at S473 is reversed in cells treated with insulin or overexpression of CDK2. The carboxyl terminus of p17 is necessary for interaction with CDK2 and for induction of autophagy. Furthermore, p17-mediated upregulation of LC3-II could be partially reversed by overexpression of CDK2. The present study provides mechanistic insights into cooperation between p17 and σA proteins of ARV to negatively regulate Akt by downregulating complexes of mTORC2 and CDK2/cyclin A2 and upregulating PSMB6, which together induces autophagy and cell cycle arrest and benefits virus replication.

Plant mitochondrial DNA

Plants possess mitochondrial genomes that are large and complex compared to animals. Nearly all animal mitochondrial genomes are about 16.5. kbp in length, whereas plant mitochondrial genomes range between 200-2,000 kbp. This is curious if we assume modern mitochondria originated from a common alpha-proteobacterial ancestor. Despite their size, plant mitochondrial genomes do not contain significantly more genes than their animal counterparts. Most of the additional DNA found in plant mitochondrial genomes consists of large introns, repeats and non-coding regions. Furthermore, plant mtDNA does not exist as large circular DNA molecules but mostly as a collection of linear DNA with combinations of smaller circular and branched molecules. Studies into these highly fragmented genomes heavily imply that recombination is the main mechanism driving replication of plant mtDNA.

Short communication: Calving site selection of multiparous, group-housed dairy cows is influenced by site of a previous calving

A calving cow and her newborn calf appear to have an attracting effect on periparturient cows, which may potentially influence the functionality of future motivation-based calving pen designs. In this pilot study we examined whether calving site selection of group-housed Holstein dairy cows was affected by the site of a previous calving. Ten multiparous cows moved to 1 of 2 group pens 11 (range = 4-27) d before calving were included. Each pen consisted of an open area (9 × 9 m) connected to 6 secluded areas (4.5 × 3 m each), where cows could move freely between all areas. Time of calving, location of the breaking of the amniotic sac, as well as the place of birth were recorded. In all but 1 case cows calved within a distance of 1 cow length from where the previous calving took place, suggesting that the cows did not select calving site at random. These preliminary observations indicate that choice of calving site may be affected by the site of a previous calving, potentially explained by the presence of amniotic fluids.

Chloroplast DNA Copy Number Changes during Plant Development in Organelle DNA Polymerase Mutants

Chloroplast genome copy number is very high in leaf tissue, with upwards of 10,000 or more copies of the chloroplast DNA (ctDNA) per leaf cell. This is often promoted as a major advantage for engineering the plastid genome, as it provides high gene copy number and thus is expected to result in high expression of foreign proteins from integrated genes. However, it is also known that ctDNA copy number and ctDNA integrity decrease as cells age. Quantitative PCR (qPCR) allows measurement of organelle DNA levels relative to a nuclear gene target. We have used this approach to determine changes in copy number of ctDNA relative to the nuclear genome at different ages of Arabidopsis plant growth and in organellar DNA polymerase mutants. The mutant plant lines have T-DNA insertions in genes encoding the two organelle localized DNA polymerases (PolIA and PolIB). Each of these mutant lines exhibits some delay in plant growth and development as compared to wild-type plants, with the PolIB plants having a more pronounced delay. Both mutant lines develop to maturity and produce viable seeds. Mutants for both proteins were observed to have a reduction in ctDNA and mtDNA copy number relative to wild type plants at all time points as measured by qPCR. Both DNA polymerase mutants had a fairly similar decrease in ctDNA copy number, while the PolIB mutant had a greater effect of reduction in mtDNA levels. However, despite similar decreases in genome copy number, RT-PCR analysis of PolIA mutants show that PolIB expression remains unchanged, suggesting that PolIA may not be essential to plant survival. Furthermore, genotypic analysis of plants from heterozygous parents display a strong pressure to maintain two functioning copies of PolIB. These results indicate that the two DNA polymerases are both important in ctDNA replication, and they are not fully redundant to each other, suggesting each has a specific function in plant organelles.

Transcriptome assembly, profiling and differential gene expression analysis of the halophyte Suaeda fruticosa provides insights into salt tolerance

BACKGROUND

Improvement of crop production is needed to feed the growing world population as the amount and quality of agricultural land decreases and soil salinity increases. This has stimulated research on salt tolerance in plants. Most crops tolerate a limited amount of salt to survive and produce biomass, while halophytes (salt-tolerant plants) have the ability to grow with saline water utilizing specific biochemical mechanisms. However, little is known about the genes involved in salt tolerance. We have characterized the transcriptome of Suaeda fruticosa, a halophyte that has the ability to sequester salts in its leaves. Suaeda fruticosa is an annual shrub in the family Chenopodiaceae found in coastal and inland regions of Pakistan and Mediterranean shores. This plant is an obligate halophyte that grows optimally from 200-400 mM NaCl and can grow at up to 1000 mM NaCl. High throughput sequencing technology was performed to provide understanding of genes involved in the salt tolerance mechanism. De novo assembly of the transcriptome and analysis has allowed identification of differentially expressed and unique genes present in this non-conventional crop.

RESULTS

Twelve sequencing libraries prepared from control (0 mM NaCl treated) and optimum (300 mM NaCl treated) plants were sequenced using Illumina Hiseq 2000 to investigate differential gene expression between shoots and roots of Suaeda fruticosa. The transcriptome was assembled de novo using Velvet and Oases k-45 and clustered using CDHIT-EST. There are 54,526 unigenes; among these 475 genes are downregulated and 44 are upregulated when samples from plants grown under optimal salt are compared with those grown without salt. BLAST analysis identified the differentially expressed genes, which were categorized in gene ontology terms and their pathways.

CONCLUSIONS

This work has identified potential genes involved in salt tolerance in Suaeda fruticosa, and has provided an outline of tools to use for de novo transcriptome analysis. The assemblies that were used provide coverage of a considerable proportion of the transcriptome, which allows analysis of differential gene expression and identification of genes that may be involved in salt tolerance. The transcriptome may serve as a reference sequence for study of other succulent halophytes.

Minireview: DNA replication in plant mitochondria

Higher plant mitochondrial genomes exhibit much greater structural complexity compared to most other organisms. Unlike well-characterized metazoan mitochondrial DNA (mtDNA) replication, an understanding of the mechanism(s) and proteins involved in plant mtDNA replication remains unclear. Several plant mtDNA replication proteins, including DNA polymerases, DNA primase/helicase, and accessory proteins have been identified. Mitochondrial dynamics, genome structure, and the complexity of dual-targeted and dual-function proteins that provide at least partial redundancy suggest that plants have a unique model for maintaining and replicating mtDNA when compared to the replication mechanism utilized by most metazoan organisms.

Arabidopsis thaliana organellar DNA polymerase IB mutants exhibit reduced mtDNA levels with a decrease in mitochondrial area density

Plant organelle genomes are complex and the mechanisms for their replication and maintenance remain unclear. Arabidopsis thaliana has two DNA polymerase genes, DNA polymerase IA (polIA) and polIB, that are dual targeted to mitochondria and chloroplasts and are differentially expressed in primary plant tissues. PolIB gene expression occurs at higher levels in tissues not primary for photosynthesis. Arabidopsis T-DNA polIB mutants have a 30% reduction in relative mitochondrial DNA (mtDNA) levels, but also exhibit a 70% increase in polIA gene expression. The polIB mutant shows an increase in mitochondrial numbers but a significant decrease in mitochondrial area density within the hypocotyl epidermis, shoot apex and root tips. Chloroplast numbers are not significantly different in mesophyll protoplasts. These mutants do not have a significant difference in total dark mitorespiration levels but exhibit a difference in light respiration levels and photosynthesis capacity. Organelle-encoded genes for components of respiration and photosynthesis are upregulated in polIB mutants. The mutants exhibited slow growth in conjunction with a decreased rate of cell expansion and other secondary phenotypic effects. Evidence suggests that early plastid development and DNA levels are directly affected by a polIB mutation but are resolved to wild-type levels over time. However, mitochondria numbers and DNA levels never reach wild-type levels in the polIB mutant. We propose that both polIA and polIB are required for mtDNA replication. The results suggest that polIB mutants undergo an adjustment in cell homeostasis, enabling them to maintain functional mitochondria at the cost of normal cell expansion and plant growth.

The Arabidopsis At1g30680 gene encodes a homologue to the phage T7 gp4 protein that has both DNA primase and DNA helicase activities

BACKGROUND

The Arabidopsis thaliana genome encodes a homologue of the full-length bacteriophage T7 gp4 protein, which is also homologous to the eukaryotic Twinkle protein. While the phage protein has both DNA primase and DNA helicase activities, in animal cells Twinkle is localized to mitochondria and has only DNA helicase activity due to sequence changes in the DNA primase domain. However, Arabidopsis and other plant Twinkle homologues retain sequence homology for both functional domains of the phage protein. The Arabidopsis Twinkle homologue has been shown by others to be dual targeted to mitochondria and chloroplasts.

RESULTS

To determine the functional activity of the Arabidopsis protein we obtained the gene for the full-length Arabidopsis protein and expressed it in bacteria. The purified protein was shown to have both DNA primase and DNA helicase activities. Western blot and qRT-PCR analysis indicated that the Arabidopsis gene is expressed most abundantly in young leaves and shoot apex tissue, as expected if this protein plays a role in organelle DNA replication. This expression is closely correlated with the expression of organelle-localized DNA polymerase in the same tissues. Homologues from other plant species show close similarity by phylogenetic analysis.

CONCLUSIONS

The results presented here indicate that the Arabidopsis phage T7 gp4/Twinkle homologue has both DNA primase and DNA helicase activities and may provide these functions for organelle DNA replication.

Identification of a soybean chloroplast DNA replication origin-binding protein

Replication of chloroplast DNA (ctDNA) in several plants and in Chlamydomonas reinhardii has been shown to occur by a double displacement loop (D-loop) mechanism and potentially also by a rolling circle mechanism. D-loop replication origins have been mapped in several species. Minimal replication origin sequences used as probes identified two potential binding proteins by southwestern blot analysis. A 28 kDa (apparent molecular weight by SDS-PAGE analysis) soybean protein has been isolated by origin sequence-specific DNA affinity chromatography from total chloroplast proteins. Mass spectrometry analysis identified this protein as the product of the soybean C6SY33 gene (accession number ACU14156), which is annotated as encoding a putative uncharacterized protein with a molecular weight of 25,897 Da, very near the observed molecular weight of the purified protein based on gel electrophoresis. Western blot analysis using an antibody against a homologous Arabidopsis protein indicates that this soybean protein is localized specifically in chloroplasts. The soybean protein shares some homology within a single-stranded DNA binding (SSB) domain of E. coli SSB and an Arabidopsis thaliana mitochondrial-localized SSB of about 21 kDa (mtSSB). However, the soybean protein induces a specific electrophoretic mobility shift only when incubated with a double-stranded fragment containing the previously mapped ctDNA replication oriA region. This protein has no electrophoretic mobility shift activity when incubated with single-stranded DNA. In contrast, the Arabidopsis mtSSB causes a mobility shift only with single-stranded DNA but not with the oriA fragment or with control dsDNA of unrelated sequence. These results suggest that the 26 kDa soybean protein is a specific origin binding protein that may be involved in initiation of ctDNA replication.

Electroencephalographic prediction of anoxic brain damage after resuscitation from cardiac arrest in patients with acute myocardial infarction

The short-term prognostic value of routine electroencephalography (EEG), carried out on the days after cardiac arrest, was evaluated in a consecutive study of 185 patients with acute myocardial infarction together with an episode of clinical cardiac arrest. The individual EEGs were classified on a 5-grade scale. Of the 89 patients who survived, 18 had signs of anoxic brain damage; 96 patients died, 76 as a result of cerebral anoxia. Only 2 patients survived out of the total of 72 for whom the first EEG was classified as grades III--V. The EEGs of both these patients were recorded within a few hours after the cardiac arrest. None of the patients with an EEG of grade I died of cerebral anoxia, while all degrees of brain damage were otherwise observed in connection with EEGs of both grades I and II. It is concluded that an EEG of grades III--V indicates a fatal outcome, provided it has been recorded more than 24 hours after the cardiac arrest. A grade III--V EEG that is recorded within 24 hours after a cardiac arrest should be repeated some days later. It is not possible, on the basis of a single EEG, to predict the extent of the anoxic brain damage.

Praecordial ECG mapping in acute anterior myocardial infarction. The evolution of ST segment and Q and R waves

Praecordial ECG mapping (42 leads) was carried out in 16 patients with anterior myocardial infarction, admitted up to 3 hours after the onset of symptoms. The mappings were performed according to a set time schedule throughout the acute phase and one year after the infarction. For each ECG map the number of leads with ST elevation greater than or equal to 1.5 mm (NST) and the sum of these (epsilon ST) were calculated. In addition, the sum of Q amplitudes (epsilon Q) and R amplitudes (epsilon R) were determined. On average, the initial epsilon ST elevation decreased from 2 to 8 hours. A secondary increase, occurring in 14 patients, was maximal during days 2-5. Based on the appearance function of creatine kinase in plasma and the QRS alterations, it is suggested that this re-elevation of the St segment was due to infarct extension (5 pats.) or expansion (9 pats.). The course of the average NST was similar to epsilon ST. epsilon Q began to develop at 3 hours, the maximum deflection being reached after about 24 hours (range 8-45). epsilon R was falling at 2 hours; the maximum rate of decrease occurred, on average, within the first 24 hours (range 12-54). One year after the infarction, both epsilon Q and epsilon R had the same level as at 8 hours. The ST elevation at 4 hours was related to the development of Q and R waves within 24 hours, but only a weak or no correlation was found. Thus, there was very little value in predicting the development of QR changes from the ST elevation at 4 hours.

Sinus node dysfunction in acute myocardial infarction

In a retrospective study of patients admitted for acute myocardial infarction (AMI) during six years, sinus node dysfunction (SND) was detected in 20 (1.04%). Twelve had persistent sinus bradycardia, 11 sinotrial block or sinus arrest and six bradytachy syndrome. Symptoms occurred in 17 patients, 12 of whom required temporary pacing for periods up to three weeks. A permanent cardiac pacemaker was implanted in three patients with brady-tachy syndrome. Three patients died during the primary admission and six during the observation period. Follow-up after a mean observation period of 34 months showed continuous signs of SND in 11 out of 19 patients. The arrhythmia caused symptoms in five patients, two of whom had a cardiac pacemaker and two received medical treatment. It is concluded that SND appearing during an AMI persists in a high number of these patients.

Sinus node dysfunction in 128 patients. A retrospective study with follow-up

A retrospective study covering all admissions during a 6-year period revealed 128 patients with sinus node dysfunction (SND). The patients were grouped according to the ECG criteria chosen: group I 33 patients with sinus bradycardia, group II 37 with sinoatrial block/sinus arrest, group III 58 with brady-tachy syndrome. Additional heart disease, predominantly ischaemic, was found in 56%. The frequency and severity of symptoms increased from group I to group III. Pacemaker treatment was given to 40% of the cases, while medical treatment alone was successful in 17%. A follow-up including 104 patients was carried out after a mean observation period of approximately three years. Sixteen patients had died. The cause of death may have been SND per se in only one case. Five patients died of apoplectic insults or complications to such. In total, nine possible or proven systemic embolic events were found--all occurring in patients with brady-tachy syndrome. A progression of the ECG abnormality from a lower to a higher group took place in nine patients during the observation period. It is concluded that SND is a condition with a broad clinical spectrum and a stationary or slowly progressive course. In general, it carries a good prognosis. A substantial number of deaths of disabilities in patients with brady-tachy syndrome may be ascribed to systemic embolism. Long-term anticoagulant therapy is proposed in this subgroup of patients with SND.

Ultradian activity rhythms in large groups of newly hatched chicks (Gallus gallus domesticus)

A clutch of young chicks housed with a mother hen exhibit ultradian (within day) rhythms of activity corresponding to the brooding cycle of the hen. In the present study clear evidence was found of ultradian activity rhythms in newly hatched domestic chicks housed in groups larger than natural clutch size without a mother hen or any other obvious external time-keeper. No consistent synchrony was found between groups housed in different pens within the same room. The ultradian rhythms disappeared with time and little evidence of group rhythmicity remained by the third night. This disappearance over time suggests that the presence of a mother hen may be pivotal for the long-term maintenance of these rhythms. The ultradian rhythm of the chicks may also play an important role in the initiation of brooding cycles during the behavioural transition of the mother hen from incubation to brooding. Computer simulations of individual activity rhythms were found to reproduce the observations made on a group basis. This was achievable even when individual chick rhythms were modelled as independent of each other, thus no assumptions of social facilitation are necessary to obtain ultradian activity rhythms on a group level.

Western blot analysis to illustrate relative control levels of the lac and ara promoters in Escherichia coli

The lactose operon and its control is a fundamental transcriptional regulatory concept presented in introductory and many advanced molecular biology courses. Much is known about the positive and negative control mechanisms that govern levels of expression of this operon. One basic principle that is taught about the lac operon is that it is "leaky," meaning that the transcriptional control of the operon is not 100% efficient and that in wild-type cells, transcription from the promoter is never completely "off," but there is always some basal transcription. In contrast, the arabinose operon is often used as an example of a tightly controlled operon, and transcription from the ara promoter is very low in the absence of inducer. The relative levels of control of these two operons can be illustrated using Western blots of proteins expressed in the presence and absence of the appropriate inducers and antibodies against the gene products. Different times of growth and the addition of inducer can also be examined. The results are very dramatic and help to reinforce the principles of promoter control.

Foot Pad Dermatitis and Hock Burn in Broiler Chickens and Degree of Inheritance

A total of 2,118 birds from 2 strains were allocated to 12 groups of 93 to 100 each in 2 time-separated replicates. The development of foot pad dermatitis (FPD) and hock burn (HB) were recorded weekly from d 8 to slaughter on a set sample of live animals (7 per group). In addition, feet and hocks of all birds were investigated at slaughter at either 4, 6 (fast-growing strain), 8, or 10 (slow-growing strain) wk of age. Lesions were scored for both the left and right foot and classified according to a scale from 1 (no lesion) to 9 (very severe lesions) for FPD and from 1 (no lesion) to 3 (very severe lesions) for HB. No FPD lesions and very few low-grade HB lesions were found in chickens from the slow-growing strain. In the fast-growing strain, the first signs of FPD and HB were seen in wk 2. The incidence of both types of lesions increased thereafter. Foot pad dermatitis was more frequent in females (49 vs. 36%, P < 0.05). Body weight did not affect FPD, but more HB were found at higher BW (P < 0.01). Egg weight influenced neither FPD nor HB. Variance and covariance components were analyzed using a multivariate animal model, in which scores for FPD and HB were transformed into logarithmic scale. The analyses were carried out using restricted maximum likelihood algorithm. Heritabilities were estimated to be 0.31 +/- 0.12 (SE) for FPD, 0.08 +/- 0.08 for HB, and 0.38 +/- 0.13 for BW. Genetic correlations among these traits were low and nonsignificant. Phenotypic correlation between BW and FPD was low and nonsignificant and between BW and HB was 0.17 +/- 0.05 (P < 0.01). The relative high heritability of FPD and the low genetic correlation to BW suggested that genetic selection against susceptibility to FPD should be possible without negative effects on BW gain.