Haplotype sharing refines the location of an imprinted quantitative trait locus with major effect on muscle mass to a 250-kb chromosome segment containing the porcine IGF2 gene

We herein describe the fine mapping of an imprinted QTL with major effect on muscle mass that was previously assigned to distal SSC2p in the pig. The proposed approach exploits linkage disequilibrium in combination with QTL genotyping by marker-assisted segregation analysis. By identifying a haplotype shared by all "Q" chromosomes, we map the QTL to an approximately 250-kb chromosome segment containing INS and IGF2 as the only known paternally expressed genes. This considerably reinforces the candidacy of these genes, justifying their detailed analysis.     

A QTL with major effect on milk yield and composition maps to bovine Chromosome 14

A whole genome scan was undertaken in a granddaughter design comprising 1158 progeny-tested bulls in order to map QTL influencing milk yield and composition. In this paper we report the identification of a locus on the centromeric end of bovine Chromosome (Chr) 14, with major effect on fat and protein percentage as well as milk yield. The genuine nature of this QTL was verified using the grand²-daughter design, that is, by tracing the segregating QTL alleles from heterozygous grandsires to their maternal grandsons and confirming the predicted QTL allele substitution effect. Received: 30 December 1997 / Accepted: 21 February 1998     

High-resolution species-distribution model based on systematic sampling and indirect observations

Species distribution models (SDMs) are often limited by the use of coarse-resolution environmental variables and by the number of observations required for their calibration. This is particularly true in the case of elusive animals. Here, we developed a SDM by combining three elements: a database of explanatory variables, mapped at a fine resolution; a systematic sampling scheme; and an intensive survey of indirect observations. Using MaxEnt, we developed the SDM for the population of the Asiatic wild ass (Equus hemionus), a rare and elusive species, at three spatial scales: 10, 100, and 1000 m per pixel. We used indirect observations of feces mounds. We constructed 14 layers of explanatory variables, in five categories: water, topography, biotic conditions, climatic variables and anthropogenic variables. Woody vegetation cover and slopes were found to have the strongest effect on the distribution of wild ass and were included as the main predictors in the SDM. Model validation revealed that an intensive survey of feces mounds and high-resolution predictor layers resulted in a highly accurate and informative SDM. Fine-grain (10 and 100 m) SDMs can be utilized to: (1) characterize the variables influencing species distribution at high resolution and local scale, including anthropogenic effects and geomorphologic features; (2) detect potential population activity centers; (3) locate potential corridors of movement and possible isolated habitat patches. Such information may be useful for the conservation efforts of the Asiatic wild ass. This approach could be applied to other elusive species, particularly large mammals.     

Trends in Ecological Research during the Last Three Decades – A Systematic Review

It is thought that the science of ecology has experienced conceptual shifts in recent decades, chiefly from viewing nature as static and balanced to a conception of constantly changing, unpredictable, complex ecosystems. Here, we ask if these changes are reflected in actual ecological research over the last 30 years. We surveyed 750 articles from the entire pool of ecological literature and 750 articles from eight leading journals. Each article was characterized according to its type, ecological domain, and applicability, and major topics. We found that, in contrast to its common image, ecology is still mostly a study of single species (70% of the studies); while ecosystem and community studies together comprise only a quarter of ecological research. Ecological science is somewhat conservative in its topics of research (about a third of all topics changed significantly through time), as well as in its basic methodologies and approaches. However, the growing proportion of problem-solving studies (from 9% in the 1980s to 20% in the 2000 s) may represent a major transition in ecological science in the long run.     

Results of a whole genome scan targeting QTL for growth and carcass traits in a Piétrain × Large White intercross

We herein report the results of a whole genome scan performed in a Piétrain × Large White intercross counting 525 offspring to map QTL influencing economically important growth and carcass traits. We report experiment-wide significant lod scores (> 4.6 for meatiness and fat deposition on chromosome SSC2, and for average daily gain and carcass length on chromosome SSC7. Additional suggestive lod scores (> 3.3) for fat deposition are reported on chromosomes SSC1, SSC7 and SSC13. A significant dominance deviation was found for the QTL on SSC1, while the hypothesis of an additive QTL could not be rejected for the QTL on SSC7 and SSC13. No evidence for imprinted QTL could be found for QTL other than the one previously reported on SSC2.     

Mating-increases trypsin in female Drosophila hemolymph

Male-derived accessory gland proteins (Acps) are transferred to the female reproductive tract during mating and affect female reproductive maturation and behavior. Some Acps subsequently enter the female hemolymph. We hypothesized that humoral proteases are the primary effectors of Acp bioactivity by processing (activating) and/or degrading them. To test this hypothesis we examined the fate of one Acp, Drosophila melanogaster Sex Peptide (Acp70A, DrmSP), which possesses several putative serine-protease cleavage sites, in hemolymph of unmated and mated females. In D. melanogaster, DrmSP induces post-mating non-receptivity and enhances oogenesis. To determine if serine proteases regulate the duration of DrmSP activity in mated females, we performed kinetic analysis of cleavage of a synthetic N-terminal truncated DrmSP(8-36) (T-SP) with hemolymph of unmated versus mated females. We found that T-SP is cleaved more rapidly and completely in mated female hemolymph. Using LC-MS/MS analyses, we identified its primary cleavage sites, indicating that trypsin was the major endopeptidase regulating T-SP in hemolymph. This was verified in vitro by utilizing specific chromogenic serine-protease substrates and inhibitors. We propose that post-mating cleavage of DrmSP in the female hemolymph regulates the duration of the rapidly induced post-mating responses in D. melanogaster and that this is a specific example of Acp bioactivity regulated by hemolymph serine proteases.     

Effects of Xylo-Oligosaccharides on Broiler Chicken Performance and Microbiota

In broiler chickens, feed additives, including prebiotics, are widely used to improve gut health and to stimulate performance. Xylo-oligosaccharides (XOS) are hydrolytic degradation products of arabinoxylans that can be fermented by the gut microbiota. In the current study, we aimed to analyze the prebiotic properties of XOS when added to the broiler diet. Administration of XOS to chickens, in addition to a wheat-rye-based diet, significantly improved the feed conversion ratio. XOS significantly increased villus length in the ileum. It also significantly increased numbers of lactobacilli in the colon and Clostridium cluster XIVa in the ceca. Moreover, the number of gene copies encoding the key bacterial enzyme for butyrate production, butyryl-coenzyme A (butyryl-CoA):acetate CoA transferase, was significantly increased in the ceca of chickens administered XOS. In this group of chickens, at the species level, Lactobacillus crispatus and Anaerostipes butyraticus were significantly increased in abundance in the colon and cecum, respectively. In vitro fermentation of XOS revealed cross-feeding between L. crispatus and A. butyraticus. Lactate, produced by L. crispatus during XOS fermentation, was utilized by the butyrate-producing Anaerostipes species. These data show the beneficial effects of XOS on broiler performance when added to the feed, which potentially can be explained by stimulation of butyrate-producing bacteria through cross-feeding of lactate and subsequent effects of butyrate on gastrointestinal function.     

Metabarcoding analysis and fermentation performance of the dominant fungal microbiota associated with the Algerian traditional date product “Btana”

International Microbiology - The study highlights the fungal diversity of the traditional Algerian date’s product “Btana” prepared with direct Btana method (DBM) and undirect...     

Contribution of domestic animals to the identification of new genes involved in sex determination.

Among farm animals, two species present an intersex condition at a relatively high frequency: pig and goat. Both are known to contain XX sex-reversed individuals which are genetically female but with a true hermaphrodite or male phenotype. It has been clearly demonstrated that the SRY gene is not involved in these phenotypes. Consequently, autosomal or X-linked mutations in the sex-determining pathway may explain these sex-reversed phenotypes. A mutation referred to as "polled" has been characterized in goats by the suppression of horn formation and abnormal sexual differentiation. The Polled Intersex Syndrome locus (PIS) was initially located in the distal region of goat chromosome 1. The homologous human region has been precisely identified as an HSA 3q23 DNA segment containing the Blepharophimosis Ptosis Epicanthus locus (BPES), a syndrome combining Premature Ovarian Failure (POF) and an excess of epidermis of the eyelids. In order to isolate genes involved in pig intersexuality, a similar genetic approach was attempted in pigs using genome scanning of resource families. Genetic analyses suggest that pig intersexuality is controlled multigenically. Parallel to this work, gonads of fetal intersex animals have been studied during development by light and electron microscopy. The development of testicular tissue and reduction of germ cell number by apoptosis, which simultaneously occurs as soon as 50 days post co?tum, also suggests that several separate genes could be involved in pig intersexuality.