Integrating animal development: How hormones and metabolism regulate developmental transitions and brain formation

Leptin- and cytokine-like unpaired signaling in Drosophila

Animals have evolved a multitude of signaling pathways that enable them to orchestrate diverse physiological processes to tightly regulate systemic homeostasis. This signaling is mediated by various families of peptide hormones and cytokines that are conserved across the animal kingdom. In this review, we primarily focus on the unpaired (Upd) family of proteins in Drosophila which are evolutionarily related to mammalian leptin and the cytokine interleukin 6. We summarize expression patterns of Upd in Drosophila and discuss the parallels in structure, signaling pathway, and functions between Upd and their mammalian counterparts. In particular, we focus on the roles of Upd in governing metabolic homeostasis, growth and development, and immune responses. We aim to stimulate future studies on leptin-like signaling in other phyla which can help bridge the evolutionary gap between insect Upd and vertebrate leptin and cytokines like interleukin 6.

Hidden features of NAD-RNA epitranscriptome in Drosophila life cycle

Nicotinamide adenine dinucleotide (NAD), a nucleotide-containing metabolite, can be incorporated into the RNA 5'-terminus to result in NAD-capped RNA (NAD-RNA). Since NAD has been heightened as one of the most essential metabolites in cells, its linkage to RNA represents a critical but poorly studied modification at the epitranscriptomic level. Here, we design a highly sensitive method, DO-seq, to capture NAD-RNAs. Using Drosophila, we identify thousands of previously unexplored NAD-RNAs and their dynamics in the fly life cycle, from embryo to adult. We show the evidence that chromosomal clustering might be the structural basis by which co-expression can couple with NAD capping on physically and functionally linked genes. Furthermore, we note that NAD capping of cuticle genes inversely correlates with their gene expression. Combined, we propose NAD-RNA epitranscriptome as a hidden layer of regulation that underlies biological processes. DO-seq empowers the identification of NAD-capped RNAs, facilitating functional investigation into this modification.

The relationship between OXT gene polymorphisms and reproductive hormones in pregnant and lactating Awassi Ewes

BACKGROUND

Numerous genetic loci interact intricately to control reproduction in mammals. The oxytocin gene (OXT) is a promising candidate for reproductive traits in mammals. Previously, sheep and goats have been studied for the presence of the OXT polymorphism. As of yet, no polymorphisms have been identified in the OXT gene of Awassi sheep. Thus, this study was conducted to determine the effects of OXT polymorphism and litter size on reproductive hormones in pregnant and lactating Awassi ewes.

METHODS AND RESULTS

This study evaluated 232 ewes aged 3 and 4 years (123 single-progeny ewes and 109 twin-producing ewes). Serum was collected to measure reproductive hormones using ELISA kits manufactured by ELK Biotechnology. DNA was extracted from sheep blood for genotyping and sequencing to identify variations in OXT gene (exon 2, 266 bp). Genotyping analysis revealed three genotypes within 266 bp: CC, CA, and AA. Sequence analysis revealed a novel mutation in exon 2: 188 C > A. Statistical analysis showed significant associations between the 188 C > A SNP and phenotypic traits. Twin-pregnant ewes carrying CC genotypes had higher estrogen, progesterone, and follicle-stimulating hormone/luteinizing hormone levels (65.86 ± 3.87) (pg/mL), (6.51 ± 0.39) (ng/mL), and (20.22 ± 1.27) (ng/mL)/( 23.37 ± 2.14) (ng/mL) respectively, compared to CA and AA genotypes in the fourth month of twin-pregnant ewes compared to single-pregnant ewes.

CONCLUSIONS

This study found that the 188 C > A SNP negatively affected reproductive hormone levels in Awassi sheep. These findings provide breeders with a new insight into the sheep OXT gene, useful for future breeding.

Association of birth type and LHX4 gene polymorphism with reproductive hormones, growth hormone, and prolactin in Awassi ewes

BACKGROUND

LIM homeobox transcription factor 4 (LHX4) is a promising candidate gene for mammalian reproductive traits. LHX4 polymorphism has previously been associated with phenotypic traits in goats and cattle. However, there have been no LHX4 gene polymorphisms identified in Awassi sheep. Therefore, this study investigated the effects of the LHX4 polymorphism on reproductive hormones, growth hormones, and prolactin in Awassi ewes.

METHODS AND RESULTS

A total of 232 ewes between the ages of 3 and 4 years were selected for this study (123 single-progeny ewes and 109 twin-producing ewes). Serum was collected to measure reproductive hormones, growth hormone, and prolactin using ELISA kits made by ELK Biotechnology. Genomic DNA was extracted from sheep blood, genotyped, and sequenced to confirm variations in LHX4 (exon 1, 207 bp). Genotyping revealed three genotypes in 207 bp: AA, AG, and GG. Sequence analysis detected a novel mutation in exon 1: 160 A > G. Statistically, the 160 A > G SNP was significantly associated with the phenotypic traits. Ewes carrying AA genotypes had higher estrogen, progesterone, follicle-stimulating hormones/luteinizing hormones, and growth hormone, and lower prolactin levels (65.63 ± 3.84) (pg/mL), (6.67 ± 0.38) (ng/mL), (22.34 ± 1.27) (ng/mL)/(23.89 ± 2.13) (ng/mL), (1.30 ± 0.05) (ng/mL), and (13.16 ± 0.75) (pg/mL), respectively, compared to AG and GG genotypes in the fourth month of twin-pregnant ewes compared to single-pregnant ewes.

CONCLUSION

This study suggests that the 160 A > G SNP negatively affects the Awassi sheep's hormone levels. It provides valuable insight into the sheep LHX4 gene, which could be an effective marker in marker-assisted selection.

Comparison of Rumen Fermentation Parameters and Microbiota of Yaks From Different Altitude Regions in Tibet, China

Rumen microbiota are closely linked to feed utilization and environmental adaptability of ruminants. At present, little is known about the influence of different extreme environments on the rumen microbiota of yaks. In this study, 30 ruminal fluid samples from 30 healthy female yaks (average 280 kg of BW) in 5–8 years of life were collected from three regions in Tibet, China, and compared by gas chromatography and high-throughput sequencing. Results showed that propionic acid, butyric acid, and total volatile fatty acids were significantly (p < 0.05) higher, while microbial abundance and diversity were significantly (p < 0.05) lower, in the Nagqu (4,500 m altitude) compared with the Xigatse (4,800 m altitude) and Lhasa (3,800 m altitude) regions. Principal coordinate analysis revealed significant (p < 0.05) differences in rumen microbial composition of yaks from different regions. Specifically, Bacteroidetes and Firmicutes were identified by linear discriminant analysis effect size (LDA > 3) as being the signature phyla for Xigatse and Nagqu regions, respectively. In addition, the relative abundance of Rikenellaceae_RC9_gut_group, Quinella, Prevotellaceae_UCG-003, Lachnospiraceae_NK3A20_group, Papillibacter, Ruminococcaceae_UCG-010, Prevotellaceae_NK3B31_group, and Ruminococcaceae_UCG-005 correlated with altitude and rumen fermentation parameters (p < 0.05). Finally, the predicted function of rumen microbiota was found to differ between regions (p < 0.05). In summary, our results reveal that regions located at different altitudes influence microbiota composition and fermentation function of yaks’ rumen. The present findings can provide mechanistic insights on yak adaptation to high altitudes and improve the feeding efficiency of these animals in extreme regions.