The genetics of resilience and its relationships with egg production traits and antibody traits in chickens

BACKGROUND

Resilience is the capacity of an animal to be minimally affected by disturbances or to rapidly return to its initial state before exposure to a disturbance. Resilient livestock are desired because of their improved health and increased economic profit. Genetic improvement of resilience may also lead to trade-offs with production traits. Recently, resilience indicators based on longitudinal data have been suggested, but they need further evaluation to determine whether they are indeed predictive of improved resilience, such as disease resilience. This study investigated different resilience indicators based on deviations between expected and observed egg production (EP) by exploring their genetic parameters, their possible trade-offs with production traits, and their relationships with antibody traits in chickens.

METHODS

Egg production in a nucleus breeding herd environment based on 1-week-, 2-week-, or 3-week-intervals of two purebred chicken lines, a white egg-laying (33,825 chickens) and a brown egg-laying line (34,397 chickens), were used to determine deviations between observed EP and expected average batch EP, and between observed EP and expected individual EP. These deviations were used to calculate three types of resilience indicators for two life periods of each individual: natural logarithm-transformed variance (ln(variance)), skewness, and lag-one autocorrelation (autocorrelation) of deviations from 25 to 83 weeks of age and from 83 weeks of age to end of life. Then, we estimated their genetic correlations with EP traits and with two antibody traits.

RESULTS

The most promising resilience indicators were those based on 1-week-intervals, as they had the highest heritability estimates (0.02-0.12) and high genetic correlations (above 0.60) with the same resilience indicators based on longer intervals. The three types of resilience indicators differed genetically from each other, which indicates that they possibly capture different aspects of resilience. Genetic correlations of the resilience indicator traits based on 1-week-intervals with EP traits were favorable or zero, which means that trade-off effects were marginal. The resilience indicator traits based on 1-week-intervals also showed no genetic correlations with the antibody traits, which suggests that they are not informative for improved immunity or vice versa in the nucleus environment.

CONCLUSIONS

This paper gives direction towards the evaluation and implementation of resilience indicators, i.e. to further investigate resilience indicator traits based on 1-week-intervals, in breeding programs for selecting genetically more resilient layer chickens.

A promising resilience parameter for breeding: the use of weight and feed trajectories in growing pigs

BACKGROUND

Increasing resilience is a priority in modern pig breeding. Recent research shows that general resilience can be quantified via variability in longitudinal data. The collection of such longitudinal data on weight, feed intake and feeding behaviour in pigs has been facilitated by the development of technologies such as automated feeding stations. The goal of this study was to investigate resilience traits, which were estimated as deviations from longitudinal weight, feed intake and feeding behaviour data during the finishing phase. A dataset with 324,207 records between the age of 95 and 155 days on 5,939 Piétrain pigs with known pedigree and genomic information was used. We provided guidelines for a rigid quality control of longitudinal body weight data, as we found that outliers can significantly affect results. Gompertz growth curve analysis, linear modelling and trajectory analyses were used for quantifying resilience traits.

RESULTS

To our knowledge, this is the first study comparing resilience traits from longitudinal body weight, feed intake and feeding behaviour data in pigs. We demonstrated that the resilience traits are lowly to moderately heritable for deviations in body weight (h² = 2.9%-20.2%), in feed intake (9.4%-23.3%) and in feeding behaviour (16.2%-28.3%). Additionally, these traits have good predictive abilities in cross-validation analyses. Deviations in individual body weight and feed intake trajectories are highly correlated (r_g = 0.78) with low to moderate favourable genetic correlations with feed conversion ratio (r_g = 0.39-0.49). Lastly, we showed that some resilience traits, such as the natural logarithm of variances of observed versus predicted body weights (lnvar_weight), are more robust to lower observation frequencies and are repeatable over three different time periods of the finishing phase.

CONCLUSIONS

Our results will help future studies investigating resilience traits and resilience-related traits. Moreover, our study provides first results on standardization of quality control and efficient data sampling from automated feeding station data. Our findings will be valuable for breeding organizations as they offer evidence that pigs' general resilience can be selected on with good accuracy. Moreover, this methodology might be extended to other species to quantify resilience based on longitudinal data.

O-136 Myeloperoxidase Kit as valuable alternative for LeucoScreen to differentiate round cells in semen samples

Study question

Is Myeloperoxidase Kit, validated for blood but not for semen, a valuable alternative for Leucoscreen to differentiate round cells in semen?

Summary answer

Myeloperoxidase Kit is a non-toxic alternative for LeucoScreen to differentiate round cells in semen, with the advantage of assessing a 1:2 dilution of semen.

What is known already

As stated in the WHO laboratory manual, the routine assay of peroxidase activity is useful as screening technique for quantifying the leucocyte population in semen samples. The clinically relevant neutrophil leucocytes stain peroxidase positive and can hereby be differentiated from spermatids and spermatocytes. The commercially available kit, Leucoscreen (Fertipro, Beernem, Belgium) uses carcinogenic ortho-toluidine and was therefore withdrawn from the market and an alternative, LeucoScreen Plus, was suggested. A disadvantage of LeucoScreen Plus is the necessity to dilute the sample 1:6. Testing an alternative inexpensive, quick and not carcinogenic method to differentiate round cells without excessive dilutions, is worth investigating.

Study design, size, duration

Intra- and inter-variability of Myeloperoxidase Kit (Ral Diagnostics, MLS NV, Menen, Belgium) was assessed by evaluating 2 semen samples 10 times by one technician, and 10 semen samples by 2 technicians, respectively. The stability of the working solution for 5 days was tested on 10 semen samples. The accuracy was tested on 80 samples by comparing Myeloperoxidase Kit with LeucoScreen. The study was performed from July till November 2020.

Participants/materials, setting, methods

Working solution was made from the Myeloperoxidase Kit (3/5 bottles): 1 ml alphanaphtol solution, 4 ml pyronine solution and 1 droplet hydrogen peroxide. Semen samples brought to the Andrology Lab for diagnostic evaluation and presenting with round cells were included. To differentiate peroxidase positive leucocytes (dark pink with dark granules) from other round cells (unstained or pink), 10 µl solution was mixed with 10 µl of semen and assessed with phase contrast at 400x.

Main results and the role of chance

The intra-variability of round cell differentiation was acceptable with %CV 6.6% for sample 1 (mean ± SD: 30.8% ± 2.04%) and 4.1% for sample 2 (mean ± SD: 56.7% ± 2.31%), both lower than the 10% criterium. The inter-variability was acceptable according to Passing&Bablok (95%CI Intercept A: -1.25 to 0.36; 95%CI Slope B: 0.92 to 1.11) and Spearman rank correlation coefficient (r = 0.983 with P < 0.001). The stability of the working solution after 5 days, kept at room temperature during the day and at 4 °C at night, compared with freshly made working solution was adequate according to Passing&Bablok (95%CI Intercept A: -2.33 to 0.47; 95%CI Slope B: 0.85 to 1.17) and Spearman rank correlation coefficient (r = 0.991 with P < 0.0001). Also the accuracy could be accepted as the Bland-Altman plot shows a substantial agreement between Leucoscreen and Myeloperoxidase Kit (difference 0.6%) without a proportional bias.

Limitations, reasons for caution

Granules in neutrophils stain differently with Myeloperoxidase Kit, with Leucoscreen and with Leucoscreen Plus, which requires a short adaptation when starting with a new kit.

Wider implications of the findings

The use of Myeloperoxidase Kit to differentiate round cells in semen is cheap, non-toxic and easy. It is a valuable asset in the andrology lab because semen samples with low round cell concentrations can be counted in a 1:2 dilution and the working solution can be kept for 5 days.

Trial registration number

None

O-016 Variability of sperm DNA fragmentation in a longitudinal trial of intrauterine inseminations

Study question

Does variability in sperm DNA fragmentation (SDF) follow that observed in standard semen parameters and is this linked to outcome results?

Summary answer

Variability in SDF and in semen parameters is comparable but live birth rate tends to be lower in men with repetitive high SDF.

What is known already

Environmental, technical and biological factors are implicated in the intra-individual variability observed in routine semen parameters. This variation is not observed in SDF testing using the sperm chromatin structure assay. Most laboratories undertake SDF testing on one semen sample, assuming that one single measurement represents the patient’s condition and is both stable and associated with a good diagnostic value. Most variability observed in SDF tests relies essentially on paired observations with a short or long time interval between test and retest.

Study design, size, duration

A monocentric, prospective cohort study was conducted October 2017 - October 2020. Couples with a mild or unexplained male infertility initiated a natural cycle IUI protocol until pregnancy was achieved for a maximum of four cycles. 313 semen samples from 112 men were analyzed for SDF before and after semen preparation. This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO), Research Foundation Flanders (grant number T007016N).

Participants/materials, setting, methods

Semen samples were analyzed and prepared by density gradient centrifugation. SDF was assessed via TUNEL assay before and after preparation. Clinical pregnancies and live births were registered. Intraclass Correlation Coefficients (ICC) were used to estimate the intra- and inter-variability.

Main results and the role of chance

The ICC for SDF (0.33 in the ejaculate, 0.54 after density gradient) and semen variables (0.42-0.62) were comparable. These values mean considerable intra-individual variation, both for semen variables and for SDF variables.

Using fertile threshold SDF values (13% before and 8% after density gradient), 3 patient groups were distinguished: 13.4% of men showed high SDF in all ejaculates, 58.0% always showed low SDF and 28.6% fluctuated between the two during the trial. After density gradient more patients were found in the High group (42.3%) and less patients in the Low group (26.1%), while the proportion of Fluctuaters remained constant (31.5%). Most (66.7%) men with high SDF retain their high SDF after gradient, and also 56.3% of the Fluctuaters react with a high SDF after gradient. The Low SDF category, on the contrary, distributes itself evenly between the three categories after gradient.

In the 112 couples, 26 (23.2%) clinical pregnancies were obtained with 21 (18.8%) live births. The live birth rate for the High, Fluctuaters and Low groups was 6.7%, 18.8% and 20.0% for ejaculate SDF and 12.8%, 20.0% and 27.6% for SDF after density gradient. These differences however did not reach significance (chi-square testing, p > 0.05).

Limitations, reasons for caution

Our results need to be substantiated and opportunities created to explore populations with an extreme male factor and the clinical implications in different assisted reproductive techniques.

Wider implications of the findings

SDF testing provides additional information and helps identify causes otherwise missed with traditional semen analysis alone. One out of 3 patients fluctuate in their SDF values. A second SDF testing is advocated to isolate these fluctuaters. The detection of DNA damage after semen preparation is indispensable for therapeutic purposes.

Trial registration number

NCT03319654

Long-Term Artificial Selection for Increased Larval Body Weight of Hermetia illucens in Industrial Settings

Black soldier fly (Hermetia illucens) farming has exponentially increased in recent years due to the ability of its larvae to efficiently convert low-grade organic materials into high-value food, feed, and technical products. There is a need to further improve the efficiency of production, to meet the rising demands for proteins in the feed and food industries under limited resources. One means of improvement is artificial selection, which has been widely applied in plants and in other livestock species. In 2019, a genetic improvement program was started with the aim to increase larval body weight in black soldier fly larvae. In this paper, we present the outcomes of this breeding program after 10, 13, and 16 generations of selection. The performance of the selected body weight line was compared to the base population line over six experimental rounds under different environmental conditions. Under automated production settings, an average increase of +39% in larval weight, +34% in wet crate yield, +26% in dry matter crate yield, +32% in crude protein per crate, and +21% crude fat per crate was achieved in the selected line compared to the base population line. This research demonstrates the potential contribution of artificial selection to improve efficiency when farming black soldier flies in industrial settings. Further research is needed to fully unlock that potential.

Using egg production longitudinal recording to study the genetic background of resilience in purebred and crossbred laying hens

Background

There is growing interest in using genetic selection to obtain more resilient farm animals (i.e. that are minimally affected by disturbances or rapidly recover from them). The aims of this study were to: (i) estimate the genetic parameters of resilience indicator traits based on egg production data, (ii) assess whether these traits are genetically correlated in purebreds and crossbreds, and (iii) assess the genetic correlations of these traits with egg production (EP) as total number of eggs between 25 and 83 weeks. Purebred hens (33,825 from a White Leghorn (WA) line and 34,397 from a Rhode Island (BD) line were housed in individual cages, while crossbred hens were housed in collective cages of 6 to 8 paternal half-sibs (12,852 WA and 3898 BD crossbred groups, where the name of the group refers to the line used as the sire). Deviations of a hen’s weekly egg production from the average of the corresponding batch were calculated. Resilience indicator traits investigated were the natural logarithm of the variance (LNVAR), the skewness (SKEW), and the lag-one autocorrelation (AUTO-R) of these deviations.

Results

In both purebred lines, EP was estimated to be lowly heritable (WA: 0.11 and BD: 0.12). Resilience indicators were also estimated to be lowly heritable in both lines (LNVAR: 0.10 and 0.12, SKEW: 0.04 and 0.02, AUTO-R: 0.06 and 0.08 in WA and BD, respectively). In both crossbred groups, EP, AUTO-R, and SKEW were estimated to be less heritable than in purebreds (EP: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$h^{2}$$\end{document}h2 ≤ 0.07; and resilience indicator traits: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$h^{2}$$\end{document}h2 ≤ 0.03), while LNVAR had an \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$h^{2}$$\end{document}h2 estimate that was similar to or higher in crossbreds (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$h^{2}$$\end{document}h2 ranged from 0.13 to 0.21) than in purebreds. In both purebreds and crossbreds, resilience indicator traits were estimated to have favorable genetic correlations with EP and between each other. For all traits and in both lines, estimates of genetic correlations between purebreds and crossbreds (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$r_{pc}$$\end{document}rpc) differed from 1 and ranged from 0.16 to 0.63.

Conclusions

These results show that selection for resilience based on EP data can be considered in breeding programs for layers. Genetic improvement of resilience in crossbreds can be achieved by using information on purebreds, but would be greatly enhanced by the integration of information on crossbreds in breeding programs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-022-00716-8.

Prevalence of nodal involvement in rectal cancer after chemoradiotherapy

BACKGROUND

The purpose of this study was to investigate the prevalence of ypN+ status according to ypT category in patients with locally advanced rectal cancer treated with chemoradiotherapy and total mesorectal excision, and to assess the impact of ypN+ on disease recurrence and survival by pooled analysis of individual-patient data.

METHODS

Individual-patient data from 10 studies of chemoradiotherapy for rectal cancer were included. Pooled rates of ypN+ disease were calculated with 95 per cent confidence interval for each ypT category. Kaplan-Meier and Cox regression analyses were undertaken to assess influence of ypN status on 5-year disease-free survival (DFS) and overall survival (OS).

RESULTS

Data on 1898 patients were included in the study. Median follow-up was 50 (range 0-219) months. The pooled rate of ypN+ disease was 7 per cent for ypT0, 12 per cent for ypT1, 17 per cent for ypT2, 40 per cent for ypT3, and 46 per cent for ypT4 tumours. Patients with ypN+ disease had lower 5-year DFS and OS (46.2 and 63.4 per cent respectively) than patients with ypN0 tumours (74.5 and 83.2 per cent) (P < 0.001). Cox regression analyses showed ypN+ status to be an independent predictor of recurrence and death.

CONCLUSION

Risk of nodal metastases (ypN+) after chemoradiotherapy increases with advancing ypT category and needs to be considered if an organ-preserving strategy is contemplated.

Time intervals between semen production, initiation of analysis, and IUI significantly influence clinical pregnancies and live births

PURPOSE

Does IDEF mapping help monitor the technical process of IUI and explore the potential improvements which might contribute to increased pregnancy and live birth rates?

METHOD

Retrospective analysis of 1729 homologous IUI cycles of couples attending a fertility clinic in a university hospital setting. Standardized conventional semen parameters were analyzed and the semen samples prepared via discontinuous density gradient centrifugation.

RESULTS

There was no significant association between sperm concentration, motility and morphology (analysis phase), and pregnancy outcome. Only female and male ages were significantly associated with the pregnancy outcome. There was a significant difference in the odds on clinical pregnancies and live births when analysis was ≤ 21 min initiated, and < 107 min between sample production and IUI, adjusted for male and female age.

CONCLUSIONS

Adjusting for the couple's age, we could show that time intervals between semen production and analysis and IUI when kept low significantly influenced clinical pregnancies and live births.

DNA fragmentation in concert with the simultaneous assessment of cell viability in a subfertile population: establishing thresholds of normality both before and after density gradient centrifugation

PURPOSE

TUNEL assay is the most common, direct test for sperm chromatin integrity assessment. But, lack of standardized protocols makes interlaboratory comparisons impossible. Consequently, clinical thresholds to predict the chance of a clinical pregnancy also vary with the technique adopted. This prospective study was undertaken to assess the incidence of sperm DNA fragmentation in a subfertile population and to establish threshold values of normality as compared to a fertile cohort, both before and after density gradient centrifugation in the total and vital fractions.

METHOD

Men presenting at a university hospital setup for infertility treatment. DNA damage via TUNEL assay was validated on fresh semen samples, as conventional semen parameters, to reduce variability of results.

RESULTS

Total DNA fragmentation in the neat semen was significantly higher in the subfertile group, but the vital fraction was not significantly different between the two cohorts. After gradient centrifugation, DNA fragmentation increased significantly in the total fraction of the subfertile group but decreased significantly in the vital fraction. In the fertile cohort, there was a non-significant increase in total fragmentation and in the vital fraction the trend was unclear.

CONCLUSIONS

Estimating total and vital sperm DNA fragmentation, after density gradient centrifugation, increased both the sensitivity and the specificity, thereby lowering the number of false negatives and false positives encountered. These findings provide opportunities to investigate the significance of the total and the vital fractions after different assisted reproductive technologies.

Meckel's enterolith : a rare cause of mechanical small bowel subobstruction

Meckel's diverticulum is the most common congenital gastrointestinal malformation and may present with bleeding, obstruction and diverticulitis. Symptomatic Meckel's diverticulum is associated with age <50 years, male gender, diverticular length > 2 cm and ectopic mucosa. Formation of enteroliths is a rare complication of Meckel's diverticulum and the majority of stones will remain in the diverticulum. Factors promoting enterolith formation through precipitation of calcium in the small intestinal alkaline environment include stasis as well as diverticular anatomy and histology. Mechanical obstruction due to liberation of enteroliths is even more rare and other mechanisms include intussusception, adhesions, volvulus and neoplasms. Visualization of enteroliths on plain abdominal films is challenging because not all stones are radiopaque. Surgical diverticulectomy or segmental bowel resection with anastomosis is preferred in case of complications. We present a case of mechanical small bowel sub-obstruction resulting from an expelled Meckel's enterolith.

Validating semen processing for an intrauterine program should take into consideration the inputs, actions and the outputs of the process

To validate semen preparation via density gradient centrifugation, we took into account the input via the semen sample, the action generated by technical and equipment characteristics and the output measured by the level of performance. Longer periods of abstinence reduced % yield, but increased viscosity and incomplete samples collected had no effect. Under controlled technical and equipment characteristics, precision and reproducibility were validated for density gradient. Additionally, as a good laboratory practice, internal and external quality control measures were implemented to guarantee the level of performance. Inseminating motile sperm count is an important predictive parameter for IUI success. In our group of patients, a yield of an absolute lower limit of 2 million motile spermatozoa was sufficient to contemplate IUI. Pregnancy rate of 13.8% where >2 million rapid progressive spermatozoa were inseminated was significantly higher than the pregnancies (4.4%) obtained with <2 million rapid progressive spermatozoa. This percentage was even higher than the national data registered for IUI (12.2%). To make IUI an attractive first-line treatment, standardization and proper validation of semen preparation procedure are mandatory.

Genomic prediction of survival time in a population of brown laying hens showing cannibalistic behavior

BACKGROUND

Mortality due to cannibalism causes both economic and welfare problems in laying hens. To limit mortality due to cannibalism, laying hens are often beak-trimmed, which is undesirable for animal welfare reasons. Genetic selection is an alternative strategy to increase survival and is more efficient by taking heritable variation that originates from social interactions into account, which are modelled as the so-called indirect genetic effects (IGE). Despite the considerable heritable variation in survival time due to IGE, genetic improvement of survival time in laying hens is still challenging because the detected heritable variation of the trait with IGE is still limited, ranging from 0.06 to 0.26, and individuals that are still alive at the end of the recording period are censored. Furthermore, survival time records are available late in life and only on females. To cope with these challenges, we tested the hypothesis that genomic prediction increases the accuracy of estimated breeding values (EBV) compared to parental average EBV, and increases response to selection for survival time compared to a traditional breeding scheme. We tested this hypothesis in two lines of brown layers with intact beaks, which show cannibalism, and also the hypothesis that the rate of inbreeding per year is lower for genomic selection than for the traditional breeding scheme.

RESULTS AND DISCUSSION

The standard deviation of genomic prediction EBV for survival time was around 22 days for both lines, indicating good prospects for selection against mortality in laying hens with intact beaks. Genomic prediction increased the accuracy of the EBV by 35 and 32 % compared to the parent average EBV for the two lines. At the current reference population size, predicted response to selection was 91 % higher when using genomic selection than with the traditional breeding scheme, as a result of a shorter generation interval in males and greater accuracy of selection in females. The predicted rate of inbreeding per generation with truncation selection was substantially lower for genomic selection than for the traditional breeding scheme for both lines.

CONCLUSIONS

Genomic selection for socially affected traits is a promising tool for the improvement of survival time in laying hens with intact beaks.

Direct and indirect genetic effects in life-history traits of flour beetles (Tribolium castaneum)

Indirect genetic effects (IGEs) are the basis of social interactions among conspecifics, and can affect genetic variation of nonsocial and social traits. We used flour beetles (Tribolium castaneum) of two phenotypically distinguishable populations to estimate genetic (co)variances and the effect of IGEs on three life-history traits: development time (DT), growth rate (GR), and pupal body mass (BM). We found that GR was strongly affected by social environment with IGEs accounting for 18% of the heritable variation. We also discovered a sex-specific social effect: male ratio in a group significantly affected both GR and BM; that is, beetles grew larger and faster in male-biased social environments. Such sex-specific IGEs have not previously been demonstrated in a nonsocial insect. Our results show that beetles that achieve a higher BM do so via a slower GR in response to social environment. Existing models of evolution in age-structured or stage-structured populations do not account for IGEs of social cohorts. It is likely that such IGEs have played a key role in the evolution of developmental plasticity shown by Tenebrionid larvae in response to density. Our results document an important source of genetic variation for GR, often overlooked in life-history theory.

The prospects of selection for social genetic effects to improve welfare and productivity in livestock

Social interactions between individuals living in a group can have both positive and negative effects on welfare, productivity, and health of these individuals. Negative effects of social interactions in livestock are easier to observe than positive effects. For example, laying hens may develop feather pecking, which can cause mortality due to cannibalism, and pigs may develop tail biting or excessive aggression. Several studies have shown that social interactions affect the genetic variation in a trait. Genetic improvement of socially-affected traits, however, has proven to be difficult until relatively recently. The use of classical selection methods, like individual selection, may result in selection responses opposite to expected, because these methods neglect the effect of an individual on its group mates (social genetic effects). It has become clear that improvement of socially-affected traits requires selection methods that take into account not only the direct effect of an individual on its own phenotype but also the social genetic effects, also known as indirect genetic effects, of an individual on the phenotypes of its group mates. Here, we review the theoretical and empirical work on social genetic effects, with a focus on livestock. First, we present the theory of social genetic effects. Subsequently, we evaluate the evidence for social genetic effects in livestock and other species, by reviewing estimates of genetic parameters for direct and social genetic effects. Then we describe the results of different selection experiments. Finally, we discuss issues concerning the implementation of social genetic effects in livestock breeding programs. This review demonstrates that selection for socially-affected traits, using methods that target both the direct and social genetic effects, is a promising, but sometimes difficult to use in practice, tool to simultaneously improve production and welfare in livestock.

Using pooled data to estimate variance components and breeding values for traits affected by social interactions

BACKGROUND

Through social interactions, individuals affect one another's phenotype. In such cases, an individual's phenotype is affected by the direct (genetic) effect of the individual itself and the indirect (genetic) effects of the group mates. Using data on individual phenotypes, direct and indirect genetic (co)variances can be estimated. Together, they compose the total genetic variance that determines a population's potential to respond to selection. However, it can be difficult or expensive to obtain individual phenotypes. Phenotypes on traits such as egg production and feed intake are, therefore, often collected on group level. In this study, we investigated whether direct, indirect and total genetic variances, and breeding values can be estimated from pooled data (pooled by group). In addition, we determined the optimal group composition, i.e. the optimal number of families represented in a group to minimise the standard error of the estimates.

METHODS

This study was performed in three steps. First, all research questions were answered by theoretical derivations. Second, a simulation study was conducted to investigate the estimation of variance components and optimal group composition. Third, individual and pooled survival records on 12 944 purebred laying hens were analysed to investigate the estimation of breeding values and response to selection.

RESULTS

Through theoretical derivations and simulations, we showed that the total genetic variance can be estimated from pooled data, but the underlying direct and indirect genetic (co)variances cannot. Moreover, we showed that the most accurate estimates are obtained when group members belong to the same family. Additional theoretical derivations and data analyses on survival records showed that the total genetic variance and breeding values can be estimated from pooled data. Moreover, the correlation between the estimated total breeding values obtained from individual and pooled data was surprisingly close to one. This indicates that, for survival in purebred laying hens, loss in response to selection will be small when using pooled instead of individual data.

CONCLUSIONS

Using pooled data, the total genetic variance and breeding values can be estimated, but the underlying genetic components cannot. The most accurate estimates are obtained when group members belong to the same family.

Alzheimer risk associated with a copy number variation in the complement receptor 1 increasing C3b/C4b binding sites

Two multicentre genome-wide association (GWA) studies provided substantial evidence, implicating the complement receptor 1 gene (CR1) in Alzheimer disease (AD) genetic etiology. CR1 encodes a large transmembrane receptor with a crucial role in the immune complement cascade. We performed a genetic follow-up of the GWA CR1 association in a Flanders-Belgian cohort (n=1883), and investigated the effect of single-nucleotide polymorphisms (SNPs) located in the CR1 locus on AD risk and cerebrospinal fluid (CSF) biomarker levels. We obtained significant association (P(adj)<0.03; odds ratio (OR)=1.24 (95% confidence interval (CI): 1.02-1.51)) for one CR1 risk haplotype, and haplotype association was strongest in individuals carrying apolipoprotein E (APOE) ɛ4 alleles (P(adj)<0.006; OR=1.50 (95% CI: 1.08-2.09)). Also, four SNPs correlated with increased CSF amyloid Aβ₁₋₄₂ levels, suggesting a role for the CR1 protein in Aβ metabolism. Moreover, we quantified a low-copy repeat (LCR)-associated copy number variation (CNV) in CR1, producing different CR1 isoforms, CR1-F and CR1-S, and obtained significant association in carriers of CR1-S. We replicated the CR1 CNV association finding in a French cohort (n=2003) and calculated in the combined cohorts, an OR of 1.32; 95% CI: 1.10-1.59 (P=0.0025). Our data showed that the common AD risk association may well be explained by the presence of CR1-S increasing the number of C3b/C4b and cofactor activity sites and AD risk with 30% in CR1-S carriers. How precisely the different functional role of CR1-S in the immune complement cascade contributes to AD pathogenesis will need additional functional studies.

Distal myopathy with upper limb predominance caused by filamin C haploinsufficiency

OBJECTIVE

In this study, we investigated the detailed clinical findings and underlying genetic defect in 3 presumably related Bulgarian families displaying dominantly transmitted adult onset distal myopathy with upper limb predominance.

METHODS

We performed neurologic, electrophysiologic, radiologic, and histopathologic analyses of 13 patients and 13 at-risk but asymptomatic individuals from 3 generations. Genome-wide parametric linkage analysis was followed by bidirectional sequencing of the filamin C (FLNC) gene. We characterized the identified nonsense mutation at cDNA and protein level.

RESULTS

Based on clinical findings, no known myopathy subtype was implicated in our distal myopathy patients. Light microscopic analysis of affected muscle tissue showed no specific hallmarks; however, the electron microscopy revealed changes compatible with myofibrillar myopathy. Linkage studies delineated a 9.76 Mb region on chromosome 7q22.1-q35 containing filamin C (FLNC), a gene previously associated with myofibrillar myopathy. Mutation analysis revealed a novel c.5160delC frameshift deletion in all patients of the 3 families. The mutation results in a premature stop codon (p.Phe1720LeufsX63) that triggers nonsense-mediated mRNA decay. FLNC transcript levels were reduced in muscle and lymphoblast cells from affected subjects and partial loss of FLNC in muscle tissue was confirmed by protein analysis.

CONCLUSIONS

The FLNC mutation that we identified is distinct in terms of the associated phenotype, muscle morphology, and underlying molecular mechanism, thus extending the currently recognized clinical and genetic spectrum of filaminopathies. We conclude that filamin C is a dosage-sensitive gene and that FLNC haploinsufficiency can cause a specific type of myopathy in humans.

Pathogen group specific risk factors at herd, heifer and quarter levels for intramammary infections in early lactating dairy heifers

Risk factors for intramammary infections caused by coagulase-negative staphylococci, contagious major pathogens and environmental major pathogens in early lactating heifers were evaluated at the herd, heifer and quarter levels. In total, 764 quarters of 191 dairy heifers in 20 randomly selected farms in Flanders (Belgium) were sampled. Quarter milk samples were collected between 1 and 4 days in milk and between 5 and 8 days in milk for bacteriological culture. Data were analyzed using multivariable, multilevel logistic regression analysis. Higher average herd milk somatic cell count (>200,000 cells/mL), not having an effective fly control strategy, contact with lactating cows prior to calving and moderate to severe udder edema prior to calving increased the odds of intramammary infections caused by contagious major pathogens. Poor heifer hygiene and lack of mineral/vitamin supplementation prior to calving were risk factors for intramammary infection caused by environmental major pathogens. Teat apex colonization with coagulase-negative staphylococci prior to calving seemed to protect quarters against intramammary infections caused by major pathogens. Poor heifer hygiene before calving, a non-clipped udder and not practicing of teat dipping prior to calving increased the odds of intramammary infection with coagulase-negative staphylococci. Although management is important in the prevention and control of intramammary infections in early lactating heifers, most variation in the prevalence of intramammary infections resided at the heifer and quarter levels, indicating that the susceptibility for intramammary infections around calving is mainly determined by heifer and quarter characteristics.

Regulators of platelet cAMP levels: clinical and therapeutic implications

Platelets are indispensable for primary haemostasis, but their function needs to be tightly regulated to prevent excessive platelet activity, possibly leading to atherothrombotic events. An important mediator of the platelet activity is cyclic AMP (cAMP), which inhibits platelet aggregation. Intracellular cAMP levels are regulated via the Gs and Gi alpha subunits of heterotrimeric G proteins, which couple to adenylyl cyclase to respectively stimulate or inhibit cAMP production. Binding of a ligand to its G protein-coupled seven-transmembrane receptor activates these G proteins. In this review, we discuss a Gs-coupled receptor on platelets, VPAC1, and 2 important Gi-coupled receptors, the ADP receptor P2Y(12) and the prostaglandin E(2) receptor EP3. The regulation of platelet cAMP levels at the level of the receptors themselves or the G proteins coupled to them is analyzed. Alterations in Gsα and Giα function are associated with altered platelet reactivity. An increase in Gs function, or alternatively a defective Gi signaling, can be a risk factor for bleeding, while a loss of Gs function can result in a prothrombotic state. Regulator of G protein signaling (RGS) proteins accelerate the rate of inactivation of G protein-mediated signaling. One of the RGS proteins, RGS2, inhibits Gs signaling by interacting directly with adenylyl cyclase. The thienopyridine class of antiplatelet agents is based on cAMP-mediated regulation of platelet function through modification of the P2Y(12) receptor. Clopidogrel and some other novel cAMP regulators are discussed. Secondly, we review the use of prostacyclin derivatives to treat pulmonary arterial hypertension.

[Comorbid anxiety disorders and alcohol-related disorders in a population of bipolar I disorder: investigation in a Flemish population]

BACKGROUND

Bipolar I disorder (bp i) is a very debilitating psychiatric disorder which is frequently associated with comorbid psychiatric and somatic disorders. Many studies in other countries show strongly elevated prevalences of anxiety disorders and alcohol-related disorders in the bp i population, but so far no data on this topic are available with regard to the Flemish population.

AIM

To determine the prevalence of anxiety disorders and alcohol-related disorders in a Flemish population of bp i outpatients in remission and to find out whether comorbidity of these disorders is linked to the onset of the disorder at a younger age.

METHOD

Sixty-nine bp i patients in remission were given structured interviews at home and the results were compared with the Belgian prevalence reported in the European Study of the Epidemiology of Mental Disorders (esemed) project. results Both the prevalence of the alcohol-related disorders (15 of 69 patients or 21.7%) and the prevalence of anxiety disorders (17 patients or 24.6%) were elevated compared to the general population (8.1 and 13.2% respectively). Among the anxiety disorders the prevalence was elevated for panic disorder, social phobia and post-traumatic stress disorder. No significant association was found between the comorbidity and the patient's age at the onset of the illness.

CONCLUSION

The prevalence of anxiety disorders and alcohol-related disorders in an outpatient population of Flemish patients with bp i in remission is elevated.

Progranulin locus deletion in frontotemporal dementia

Ubiquitin-positive, tau-negative, frontotemporal dementia (FTD) is caused by null mutations in progranulin (PGRN; HUGO gene symbol GRN), suggesting a haploinsufficiency mechanism. Since whole gene deletions also lead to the loss of a functional allele, we performed systematic quantitative analyses of PGRN in a series of 103 Belgian FTD patients. We identified in one patient (1%) a genomic deletion that was absent in 267 control individuals. The deleted segment was between 54 and 69 kb in length and comprised PGRN and two centromeric neighboring genes RPIP8 (HUGO gene symbol RUNDC3A) and SLC25A39. The patient presented clinically with typical FTD without additional symptoms, consistent with haploinsufficiency of PGRN being the only gene contributing to the disease phenotype. This study demonstrates that reduced PGRN in absence of mutant protein is sufficient to cause neurodegeneration and that previously reported PGRN mutation frequencies are underestimated.

The long term evolution of 6 adult patients with Cohen syndrome and their behavioral characteristics

Cohen syndrome is an autosomal recessive, multiple congenital anomalies/mental retardation (MCA/MR) syndrome, caused by a mutation in the COH1 gen, localized on chromosome 8q22. COH1 encodes a transmembrane protein of 4.022 amino-acids with a presumed role in vesicle-mediated sorting and intracellular protein transport. Clinical features are non progressive psychomotor retardation and microcephaly, characteristic facial features, retinal dystrophy, and intermittent neutropenia. Examination of the long-term evolution of 6 patients with Cohen syndrome shows that the clinical features are rather stable during evolution. Description of their actual behavior on the basis of standardized questionnaires shows that no severe behavior problems are observed in any of the 6 patients. Taking into account their mental age, their behavior is quiet and easy to handle by their environment.

Familial occipitotemporal lobe epilepsy and migraine with visual aura: Linkage to chromosome 9q

OBJECTIVE

To map the disease-causing locus in a large Belgian family with occipitotemporal lobe epilepsy associated with migraine with visual aura and to describe the clinical, electrophysiologic, and imaging characteristics.

METHODS

DNA samples from 21 family members were obtained and an 8 cM density genome-wide scan was performed. The authors interviewed 21 individuals and performed interictal EEG in 14 and brain MRI in 13 individuals.

RESULTS

Nine at risk family members and one deceased individual had epilepsy with occipital and temporal lobe symptomatology, variable age at onset, usually good prognosis, no epileptic EEG features, and normal brain MRI. Five of the 10 patients had a history of migraine with aura (p = 0.0026). Seizures and migraine attacks occurred as separate episodes in all but one patient. Three patients described light flashes both as epileptic and migraine aura. Epilepsy and migraine started at the same age in three patients and remitted simultaneously in two. The epileptic phenotype had a dominant mode of inheritance with a reduced penetrance of 75%. A conclusive two-point lod score of 3.3 was obtained for marker D9S257 at recombination fraction zero. Haplotype analysis defined a candidate region of 9.95 cM (5.96 Mb) between markers GATA152H04 and D9S253 located at chromosome 9q21-q22 based upon recombinations in affected individuals.

CONCLUSIONS

The clinical association in this family of occipitotemporal lobe epilepsy and migraine with visual aura and the conclusive linkage of the occipitotemporal lobe epilepsy/migraine with aura trait to a single locus suggests a common monogenic gene defect.

Familial occipitotemporal lobe epilepsy and migraine with visual aura: linkage to chromosome 9q

OBJECTIVE

To map the disease-causing locus in a large Belgian family with occipitotemporal lobe epilepsy associated with migraine with visual aura and to describe the clinical, electrophysiologic, and imaging characteristics.

METHODS

DNA samples from 21 family members were obtained and an 8 cM density genome-wide scan was performed. The authors interviewed 21 individuals and performed interictal EEG in 14 and brain MRI in 13 individuals.

RESULTS

Nine at risk family members and one deceased individual had epilepsy with occipital and temporal lobe symptomatology, variable age at onset, usually good prognosis, no epileptic EEG features, and normal brain MRI. Five of the 10 patients had a history of migraine with aura (p = 0.0026). Seizures and migraine attacks occurred as separate episodes in all but one patient. Three patients described light flashes both as epileptic and migraine aura. Epilepsy and migraine started at the same age in three patients and remitted simultaneously in two. The epileptic phenotype had a dominant mode of inheritance with a reduced penetrance of 75%. A conclusive two-point lod score of 3.3 was obtained for marker D9S257 at recombination fraction zero. Haplotype analysis defined a candidate region of 9.95 cM (5.96 Mb) between markers GATA152H04 and D9S253 located at chromosome 9q21-q22 based upon recombinations in affected individuals.

CONCLUSIONS

The clinical association in this family of occipitotemporal lobe epilepsy and migraine with visual aura and the conclusive linkage of the occipitotemporal lobe epilepsy/migraine with aura trait to a single locus suggests a common monogenic gene defect.

Attentional responses to unattended stimuli in human parietal cortex

Right-sided parietal lesions lead to lateralized attentional deficits which are most prominent with bilateral stimulation. We determined how an irrelevant stimulus in the unattended hemifield alters attentional responses in parietal cortex during unilateral orienting. A trial consisted of a central spatial cue, a delay and a test phase during which a grating was presented at 9 degrees eccentricity. Subjects had to discriminate the orientation of the grating. The unattended hemifield was either empty or contained a second, irrelevant grating. We carried out a series of functional MRI (fMRI) studies in 35 healthy volunteers (13 men and 22 women, aged between 19 and 30 years) as well as a behavioural and structural lesion mapping study in 17 right-hemispheric lesion patients, 11 of whom had neglect. In the patients with but not in those without neglect, the addition of a distractor in the unattended hemifield significantly impaired performance if attention was directed contralesionally but not if it was directed ipsilesionally. In the healthy volunteers, we discerned two functionally distinct areas along the posterior-anterior axis of the intraparietal sulcus (IPS). The posterior, descending IPS segment in both hemispheres showed attentional enhancement of responses during contralateral attentional orienting and was unaffected by the presence of an irrelevant stimulus in the ignored hemifield. In contrast, the right-sided horizontal IPS segment showed a strong attentional response when subjects oriented to a stimulus in the relevant hemifield and an irrelevant stimulus was simultaneously present in the ignored hemifield, compared with unilateral stimulation. This effect was independent of the direction of attention. The symmetrical left-sided horizontal IPS segment showed the highest responses under the same circumstances, in combination with a contralateral bias during unilateral stimulation conditions. None of the six patients without neglect had a lesion of the horizontal IPS segment. In four of the 11 neglect patients, the lesion overlapped with the horizontal IPS activity cluster and lay in close proximity to it in another four. The remaining three patients had a lesion at a distance from the parietal cortex. Our findings reconcile the role of the IPS in endogenous attentional control with the clinically significant interaction between direction of attention and bilateral stimulation in right parietal lesion patients. Functional imaging in neglect patients will be necessary to assess IPS function in those cases where the structural lesion spares the middle IPS segment.

A Markov model of treatment of newly diagnosed epilepsy in the UK. An initial assessment of cost-effectiveness of topiramate

Long-term comparative trials among newer antiepileptic drugs are lacking; therefore decision models are needed to guide treatment decisions. The goal of this study was to develop an economic model of newly diagnosed epilepsy in the UK and to provide the first assessment of topiramate. A Markov model was developed combining data from clinical trials, cost-of illness, mortality, and utility studies. Expected costs and utilities associated with treatment strategies (first- and second-line treatments) were compared to find the cost-effectiveness frontier. First- and second-line monotherapy with topiramate or carbamazepine in partial seizures was less costly and more effective than other scenarios. In generalised seizures first-line topiramate was cost-effective with valproate or lamotrigine as second-line treatments depending on the set of utilities used. Models provide a relevant framework within which costs and health gains of antiepileptic drugs treatment options can be studied. Our findings are further evidence of the promising role of topiramate for patients with newly diagnosed epilepsy.

A pooled analysis of adjunctive topiramate in refractory partial epilepsy

OBJECTIVES

To evaluate the impact of different dosages of topiramate (TPM) add-on to stable antiepileptic therapy for refractory partial epilepsy in adults.

MATERIAL AND METHODS

Pooled intention-to-treat analysis of six similarly designed double-blind, placebo-controlled trials, including 481 patients treated with doses of TPM 200, 400, 600 and 800 mg/day, and 265 patients receiving placebo.

RESULTS

Seizures were reduced by >/=50% from baseline in 41% of TPM-treated patients and 15% of placebo-treated patients (P < 0.001); 5 and 0.8%, respectively, were seizure-free (P < 0.003). TPM was significantly better than placebo regardless of gender, age, baseline seizure rate as well as number and type of concomitant antiepileptic drugs. Efficacy was statistically significant in favour of TPM at all dose levels: at least 50% seizure reduction was achieved in 40% of patients with 200 mg, 41% with 400 mg, 44% with 600 mg and 41% with 800 mg TPM when compared with 15% with placebo (P </= 0.001 for each dosage arm vs placebo). The median reduction in monthly seizure frequency was 38%, 42%, 45% and 38% vs 8%, respectively (P </= 0.001). Moreover, response to TPM was significantly superior to placebo at each of the dose levels tested for most of the baseline variables. The total percentage of withdrawals increased with the dosage, and the withdrawals caused by adverse events increased from 3% with placebo to 7% with 200 mg TPM (not significant vs placebo), 15% with 400 mg TPM (P = 0.08), 16% with 600 mg TPM (P = 0.002) and 15% with 800 mg TPM (P = 0.003).

CONCLUSION

The efficacy of TPM add-on in partial epilepsy is consistent across efficacy endpoints and independent of study population characteristics. The response at 200 mg TPM is similar to the response at higher doses, but as drop-outs caused by adverse events are more frequent above the 200 mg dose, this pooled analysis supports that 200 mg daily is a good target dose for add-on therapy in most patients with partial epilepsy, showing an excellent balance between efficacy and tolerability.

Arg123-Tyr166 domain of human ApoA-I is critical for HDL-mediated inhibition of macrophage homing and early atherosclerosis in mice

Atherosclerosis was studied in apolipoprotein E (apoE) knockout mice expressing human apolipoprotein A-I (apoA-I) or an apoA-I/apolipoprotein A-II (apoA-II) chimera in which the Arg123-Tyr166 central domain of apoA-I was substituted with the Ser12-Ala75 segment of apoA-II. High density lipoprotein (HDL) cholesterol levels were identical in apoA-I and apoA-I/apoA-II mice, but at 4 months, plaques were 2.7-fold larger in the aortic root of the apoA-I/apoA-II mice (P<0.01). The macrophage-to-smooth muscle cell ratio of lesions was 2.1-fold higher in apo-I/apoA-II mice than in apoA-I mice (P<0.01). This was due to a 2.7-fold higher (P<0.001) in vivo macrophage homing in the aortic root of apoA-I/apoA-II mice. Plasma platelet-activating factor acetyl hydrolase activity was lower (P<0.01) in apoA-I/apoA-II mice, resulting in increased oxidative stress, as evidenced by the higher titer of antibodies against oxidized low density lipoprotein (P<0.01). Increased oxidative stress resulted in increased stimulation of ex vivo macrophage adhesion by apoA-I/apoA-II beta-very low density lipoprotein and decreased inhibition of beta-very low density lipoprotein-induced adhesion by HDL from apoA-I/apoA-II mice. The cellular cholesterol efflux capacity of HDL from apoA-I/apoA-II mice was very similar to that of apoA-I mice. Thus, the Arg123-Tyr166 central domain of apoA-I is critical for reducing oxidative stress, macrophage homing, and early atherosclerosis in apoE knockout mice independent of its role in HDL production and cholesterol efflux.

Highly efficient targeting and accumulation of a F(ab) fragment within the secretory pathway and apoplast of Arabidopsis thaliana

To further improve antibody production in plants, constructs were designed to minimize transgene silencing and to retain a F(ab) fragment within the secretory pathway of transgenic Arabidopsis thaliana plants. The levels of antibody accumulation suggest that placing the sequences that encode Fd and light chain under the control of nonidentical 3' regions reduces susceptibility to post-transcriptional gene silencing compared with when the individual polypeptide-encoding sequences are placed under the control of identical 3' regions. High levels of accumulation (up to 6% of total soluble protein) were found for both secreted and intracellularly targeted antibody fragments. Immunofluorescence microscopic analysis showed that F(ab) fragments devoid of any additional C-terminal sequence were efficiently secreted, whereas retention of F(ab) fragments within the endomembrane system of the secretory pathway was achieved by C-terminal fusion of the DIKDEL sequence to the antibody light chain. Furthermore, analysis by immunoprecipitation and ELISA showed that intracellular retention of antibody fragments did not affect antigen-binding activity, and more than 80% of the isolated antibody fragments were found to bind antigen. Taken together, our results provide improvements to the technology of recombinant antibody production in transgenic plants.

Production of antibodies and antibody fragments in plants

Our current knowledge allows the generation of transgenic plants that efficiently produce heterologous proteins from plant, bacterial, fungal or animal origin. Among all types of recombinant proteins, antibodies are particularly attractive because of their ability to specifically recognize and bind virtually any type of antigen. Plants show several advantages as a large-scale antibody production system: they can be grown easily and inexpensively in large quantities that can be harvested, stored and processed by using existing infrastructures. Isolation and purification of plant-made antibodies, if necessary, allow fundamental, industrial, and therapeutical applications. In the past, we and others have successfully generated antibody-producing plants. The maximal accumulation levels of antibodies and antibody fragments that we observed are 1-5% of the extracted proteins. Currently, several biotechnological companies grow field crops to produce antibodies for ex planta applications on an industrial scale.

Distribution of pituitary adenylate cyclase-activating polypeptide and pituitary adenylate cyclase-activating polypeptide type I receptor mRNA in the chicken brain

To map in detail the brain areas in which pituitary adenylate cyclase-activating polypeptide (PACAP) may play a significant role in birds, the distribution of PACAP and PACAP type I receptor (PAC(1)-R) mRNA was examined throughout the entire chicken brain by using in situ hybridization histochemistry. Widespread distribution of both PACAP and its receptor mRNA was found. The telencephalic areas where the most intense signals for PACAP mRNA were found included the hyperstriatum accessorium, the hippocampus, and the archistriatum. In the diencephalon, a group of neurons that highly expressed PACAP mRNA was observed from the anterior medial hypothalamic nucleus to the inferior hypothalamic nucleus. Moderate expression was found in the paraventricular nucleus and the preoptic region. A second large group of neurons containing PACAP message was found within the nucleus dorsolateralis anterior thalami and extended caudally to the area around the nucleus ovoidalis and the nucleus paramedianus internus thalami. Furthermore, expression of PACAP message was observed within the bed nucleus of the pallial commissure, nucleus spiriformis medialis, optic tectum, cerebellar cortex, olfactory bulbs, and several nuclei within the brainstem (dorsal vagal and parabrachial complex, reticular formation). The highest expression of PAC(1)-R mRNA was found in the dorsal telencephalon, olfactory bulbs, lateral septum, optic tectum, cerebellum, and throughout the hypothalamus and thalamus. The presence of PACAP and PAC(1)-R mRNA in a variety of brain areas in birds suggests that PACAP mediates several physiologically important processes in addition to regulating the activity of the pituitary gland.

Sequence and distribution of pro-opiomelanocortin in the pituitary and the brain of the chicken (Gallus gallus)

Although pro-opiomelanocortin (POMC) is a well-known hormone precursor in many species, molecular information about avian POMCs is still relatively scarce. In a former study (Berghman et al., [1998] Mol Cell Endocrinol. 142:119-130) the nucleotide and amino acid sequence of N-terminal POMC in the chicken were reported. To complete the nucleotide sequence of the precursor, rapid amplification of 3' and 5' cDNA end reactions were performed and the polymerase chain reaction (PCR) products were cloned and sequenced. The chicken POMC coding region appears to consist of 678 base pairs in the pituitary and also in the hypothalamus, as assessed by reverse transcriptase PCR. Overall nucleotide sequence homology with other species ranges from 41% (in bovine) to 57% (in rat). The distribution of the POMC mRNA in pituitary and brain was analyzed by in situ hybridization by using 33P-labelled oligonucleotides. Expression of POMC mRNA in the pituitary was restricted to the cephalic lobe, whereas in the brain, the signal was limited to the hypothalamic region. As assessed by Northern blot analysis, the length of the POMC mRNA in both the pituitary and the hypothalamus was approximately 1,200 nucleotides. By using antisera to N-terminal POMC, alpha-melanotropin and beta-endorphin, POMC-containing cells were observed in the cephalic lobe of the pituitary and immunopositive perikarya were localized in the infundibular nucleus and median eminence of the hypothalamus. Immunoreactive fibers were found in the preoptic area and in the medial basal hypothalamus surrounding the third ventricle and more dorsally in the thalamus. Double-staining experiments in the pituitary clearly indicated a complete overlap of the signals generated by these antisera.