Morphometric and gross anatomy studies of gonads in day-old Arabic chick (Gallus turcicus) lead to gonadal asymmetry

The differentiation of avian gonads occurred since the embryonic stage, resulted in asymmetric morphology. This study aimed to analyse the morphometric and gross anatomy of gonads in Day old Arabic chick. This study utilized 116 Day old Arabic chick. After necropsy, they were divided into 61 male and 55 female. The variables studies were length, width, volume, location, colour, and shape of the gonads. Data analysis used descriptive analysis and independent T test. The results showed a significant difference (P<0.01) between the right and left ovary lengths 1.67±0.08 mm and 3.69±0.05, respectively. A significant difference (P<0.01) between the width ovaries 0.64±0.03 mm (right ovary) and 1.18±0.03 mm (left ovary), respectively. It was found a significant difference (P<0.05) between the length of right and left testis 2.47±0.08 mm and 3.29±0.07mm, and between volume of testis 1.46±0.12 mm3 (right testis) and 2.03±0.13 mm3 (left testis). However, the right and left testes width was not significant (P>0.01). The testes colour was creamy white, sometimes pink, and grey to black, the colour of ovaries was creamy yellow and pink. Morphometric and gonadal morphology of Day old Arabic chick showed gonadal asymmetry, and the left side is larger than the right side.

The Sexual Effect of Chicken Embryos on the Yolk Metabolites and Liver Lipid Metabolism

The metabolic processes of animals are usually affected by sex. Egg yolk is the major nutrient utilized for the growth and development of a chicken embryo. In this study, we explored the differences of yolk metabolites in male and female chicken embryos by LC–MS/MS. Furthermore, we investigated the mRNA expression of lipoprotein lipase (LPL) and fatty acid synthase (FAS) in chicken embryo liver with different sexes in different embryonic stages. The results showed that the nutrient metabolites in the yolk of female chickens were mainly related to lipid metabolism and amino acid metabolism in the early embryonic stage, and vitamin metabolism in the late embryonic stage. The male yolk metabolites were mainly associated with lipid metabolism and nucleic acid metabolism in the early developmental stage, and amino acids metabolism in the late embryonic stage. There was no significant difference in the expression of LPL or FAS in livers of male and female chicken embryos at different embryonic stages. Our results may lead to a better understanding of the sexual effect on yolk nutrient metabolism during chicken embryonic development.

Direct and Latent Effects of Pathogen Exposure Across Native and Invasive Amphibian Life Stages

Emerging infectious diseases are one of the multiple factors contributing to the current “biodiversity crisis”. As part of the worldwide biodiversity crisis, amphibian populations are declining globally. Chytridiomycosis, an emerging infectious disease, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is a major cause of amphibian population declines. This fungus primarily affects keratinized structures in larval, juvenile, and adult amphibians as well as heart function. However, we know little about how Bd can impact embryos as well as potential latent effects of Bd exposure over ontogeny. Using two different Bd strains and multiple exposure times, we examined the effects of Bd exposure in Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas) and American bullfrog (Lithobates catesbeianus) life stages. Using a factorial experimental design, embryos of these three species were exposed to Bd at early and late embryonic stages, with some individuals re-exposed after hatching. Embryonic Bd exposure resulted in differential survival as a function of host species, Bd strain and timing of exposure. P. regilla experienced embryonic mortality when exposed during later developmental stages to one Bd strain. There were no differences across the treatments in embryonic mortality of A. boreas and embryonic mortality of L. catesbeianus occurred in all Bd exposure treatments. We detected latent effects in A. boreas and L. catesbeianus larvae, as mortality increased when individuals had been exposed to any of the Bd strains during the embryonic stage. We also detected direct effects on larval mortality in all three anuran species as a function of Bd strain, and when individuals were double exposed (late in the embryonic stage and again as larvae). Our results suggest that exposure to Bd can directly affect embryo survival and has direct and latent effects on larvae survival of both native and invasive species. However, these impacts were highly context dependent, with timing of exposure and Bd strain influencing the severity of the effects.

Supplemental L-Arginine Improves the Embryonic Intestine Development and Microbial Succession in a Chick Embryo Model

Early colonization of intestinal microbiota plays an important role in intestinal development. However, the microbial succession at an embryonic stage and its assembly patterns induced by prenatal nutrition are unknown. In the present study, we used a chick embryo model to investigate the effects of in ovo feeding (IOF) of L-arginine (Arg) on the intestinal development and microbial succession of embryos. A total of 216 fertile eggs were randomly distributed into 2 groups including the non-injected control group and IOF of Arg group with 7 mg/egg. The results showed that IOF Arg increased the intestinal index, absolute weight of jejunum, and improved jejunal morphology in terms of villus width and surface area (p &lt; 0.05). The relative mRNA expressions of mTOR and 4E-BP1 were up-regulated and accompanied by higher contents of Mucin-2 in the Arg group (p &lt; 0.05). There was a significant elevation in contents of serum glucose and high-density lipoprotein cholesterol, whereas there was a decreased low-density lipoprotein cholesterol in the Arg group (p &lt; 0.05). Additionally, Proteobacteria and Firmicutes were major intestinal bacteria species at the embryonic stage. However, Arg supplementation targeted to shape assembly patterns of microbial succession and then changed microbial composition (p = 0.05). Meanwhile, several short-chain fatty acids (SCFAs)-producing bacteria, such as Roseburia, Blautia, and Ruminococcus were identified as biomarkers in the Arg group (LDA &gt; 3, p &lt; 0.05). Accordingly, significant elevated concentrations of SCFAs, including lactic acid and formic acid, were observed in the Arg group (p &lt; 0.05), accompanied by the higher concentration of butyric acid (0.05 &lt; p &lt; 0.10). In conclusion, prenatal Arg supplementation improved embryonic intestine development by regulating glucose and lipid homeostasis to supply more energy for chick embryos. The possible mechanism could be the roles of Arg in shaping the microbial assembly pattern and succession of the embryonic intestine, particularly the enrichment of potential probiotics. These findings may contribute to exploring nutritional strategies to establish health-promoting microbiota by manipulating prenatal host-microbe interactions for the healthy development of neonates.

Trilogy Development of Proopiomelanocortin Neurons From Embryonic to Adult Stages in the Mice Retina

Proopiomelanocortin-positive amacrine cells (POMC ACs) were first discovered in adult mouse retinas in 2010; however, the development of POMC-ACs has not been studied. We bred POMC-EGFP mice to label POMC-positive cells and investigated the development of POMC neurons from embryonic to adult stages. We found that POMC neuron development is mainly divided into three stages: the embryonic stage, the closed-eye stage, and the open-eye stage. Each stage has unique characteristics. In the embryonic stage, POMC neurons appeared in the retina at about E13. There was a cell number developmental peak at E15, followed by a steep decline at E16. POMC neurons showed a large soma and increased spine numbers at the closed-eye stage, and two dendritic sublaminas formed in the inner plexiform layer (IPL). The appearance and increased soma size and dendrite numbers did not occur continuously in space. We found that the soma number was asymmetric between the superior and inferior retinas according to the developmental topographic map. Density peaked in the superior retina, which existed persistently in the retinal ganglion cell layer (GCL), but disappeared from the inner nuclear layer (INL) at about P6. At the same time, the soma distribution in the INL was the most regular. At the open-eye stage, the development of POMC neurons was nearly stable only with only an increase in the IPL width, which increased the soma–dendrite distance.

Rod-genesis driven by mafba in an nrl knockout zebrafish model with altered photoreceptor compositions and progressive retinal degeneration

The neural retina leucine zipper (NRL) is an essential gene for the fate determination and differentiation of rod photoreceptors in mammals. Mutations in NRL have been associated with autosomal recessive enhanced S-cone syndrome and autosomal dominant retinitis pigmentosa. However, the exact role of Nrl in regulating the development and maintenance of photoreceptors in zebrafish, a popular animal model used for retinal degeneration and regeneration studies, has not been fully determined. In this study, we generated an nrl knockout zebrafish model by CRISPR-Cas9 technology and observed a surprising phenotype characterized by the reduction but not total elimination of rods and the over-grown of green-cones. By tracing the developmental process of rods, we discovered two waves of rod genesis in zebrafish, emerging at the embryonic stage with an nrl-dependent pattern and the post-embryonic stage with an nrl-independent pattern, respectively. Through bulk and single-cell RNA sequencing, we constructed the gene expression profiles for the whole retinal tissues and each of the retinal cell types in WT and nrl knockout zebrafish. We detected the rod/green-cone intermediate photoreceptors in nrl knockout zebrafish, suggesting that there may be a kind of rod/green-cone bipotent precursors and its fate choice between rod and green-cone is controlled by nrl. Besides, we identified the mafba gene as a novel regulator for nrl-independent rods, based on the cell-type-specific expression pattern and the retinal phenotype of nrl/mafba double knockout zebrafish. Furthermore, the altered photoreceptor compositions and abnormal gene expression caused progressive retinal degeneration and subsequent regeneration in nrl knockout zebrafish. Our work revealed a novel function of mafba gene in rod development and established a more suitable model for the developmental processes and regulatory mechanisms of rod and green-cone photoreceptors in zebrafish.

Piezo Type Mechanosensitive Ion Channel Component 1 is Required for Heart Development in Zebrafish

PIEZO1 is a non-selective cation channel protein that converts mechanical stimuli into electrochemical signals through mechanical force transmission. In recent years, more and more attention has been paid to its relationship with cardiovascular development and related diseases. However, PIEZO1 is difficult to be used as a therapeutic target due to incomplete study of its related phenotype and mechanism. Starting with the phenotypes of zebrafish at different stages of development, piezo1 knockout zebrafish features decreased heart rate in embryonic stage, increased heart size in 72dpf larvae, as well as ventricular enlargement, passivation and increased immune infiltration in adult stage. Further characterization revealed the relationship between PIEZO1 and AcanA protein at embryonic stage, and hand2 protein at adult stage. Through further RNA-seq analysis, ptpn21 downregulation, shox2 upregulation, itga4 upregulation were used to explain ventricular enlargement, heart rate decrease and immune infiltration increase respectively. Overall, this study provides a theoretical basis for elucidating the mechanism of PIEZO1 in regulating cardiac development.

The behavior and functions of embryonic microglia

Microglia are the resident immune cells of the central nervous system. Microglial progenitors are generated in the yolk sac during the early embryonic stage. Once microglia enter the brain primordium, these cells colonize the structure through migration and proliferation during brain development. Microglia account for a minor population among the total cells that constitute the developing cortex, but they can associate with many surrounding neural lineage cells by extending their filopodia and through their broad migration capacity. Of note, microglia change their distribution in a stage-dependent manner in the developing brain: microglia are homogenously distributed in the pallium in the early and late embryonic stages, whereas these cells are transiently absent from the cortical plate (CP) from embryonic day (E) 15 to E16 and colonize the ventricular zone (VZ), subventricular zone (SVZ), and intermediate zone (IZ). Previous studies have reported that microglia positioned in the VZ/SVZ/IZ play multiple roles in neural lineage cells, such as regulating neurogenesis, cell survival and neuronal circuit formation. In addition to microglial functions in the zones in which microglia are replenished, these cells indirectly contribute to the proper maturation of post-migratory neurons by exiting the CP during the mid-embryonic stage. Overall, microglial time-dependent distributional changes are necessary to provide particular functions that are required in specific regions. This review summarizes recent advances in the understanding of microglial colonization and multifaceted functions in the developing brain, especially focusing on the embryonic stage, and discuss the molecular mechanisms underlying microglial behaviors.

The League of Matteo Salvini

The Lega Nord (LN – Northern League) has undergone a profound process of transformation since 2013, byreplacing its historical regionalist populism with a new state-wide populist radical right outlook. However,very little is known about how such transformation impacted its organizational model, particularly the masspartyfeatures that characterized it under its founding leader, Umberto Bossi. This article explores theorganizational evolution of the party under Matteo Salvini by means of a qualitative in-depth analysis of 41semi-structured interviews with representatives of the League from four regions (Calabria, Emilia-Romagna,Lombardy and Veneto) and primary documents. It underlines that the LN was turned into a disempoweredand politically inactive “bad company”, charged with the task of paying the debts of the old party, while itsstructure, resources and personnel were poured into a new state-wide organization called League for SalviniPremier. This new League has not simply maintained the key features of the mass-party in the LN’s historicalstrongholds but also pioneered a modern form of this organizational model grounded on the continuousinteraction between digital and physical activism, i.e. phygital activism, which boosts the party’s ability toreach out to the electorate by delivering the image that the League is constantly on the ground. The Leaguehas sought to export this modern interpretation of the mass-party in the South; however, in that area itsorganizational development remains at an embryonic stage, and the party’s nationalization strategy has sofar produced a “quasi-colonial” structure dominated by, and dependent on, the Northern elite.