A Review of the Emerging White Chick Hatchery Disease

White chick hatchery disease is an emerging disease of broiler chicks with which the virus, chicken astrovirus, has been associated. Adult birds typically show no obvious clinical signs of infection, although some broiler breeder flocks have experienced slight egg drops. Substantial decreases in hatching are experienced over a two-week period, with an increase in mid-to-late embryo deaths, chicks too weak to hatch and pale, runted chicks with high mortality. Chicken astrovirus is an enteric virus, and strains are typically transmitted horizontally within flocks via the faecal–oral route; however, dead-in-shell embryos and weak, pale hatchlings indicate vertical transmission of the strains associated with white chick hatchery disease. Hatch levels are typically restored after two weeks when seroconversion of the hens to chicken astrovirus has occurred. Currently, there are no commercial vaccines available for the virus; therefore, the only means of protection is by good levels of biosecurity. This review aims to outline the current understanding regarding white chick hatchery disease in broiler chick flocks suffering from severe early mortality and increased embryo death in countries worldwide.

Fertility and hatchability of Japanese quail eggs under semi arid conditions in Nigeria

Some factors affecting the fertility and hatchability of Japanese quail eggs were studied at the Poultry Unit of the University of Maiduguri Livestock Teaching and Research Farm. A total of 1850 eggs were used for the study and data collected were subjected to Analysis of Variance. The mean values of fertility, hatchability of total and fertile eggs set, early, mid and late embryo mortalities were 74.33, 51.35, 69.09, 10.25, 7.57 and 12.30% respectively. Fertility was highest (84.92%) in the dry cold, least (35.58%) in the dry hot, with wet season (80.75%) being intermediate. Similarly, hatchability of total and fertile eggs set were 67.18 and 79.11% in the dry cold, 14.11 and 39.66% in the dry hot and 46.86 and 58.03% in the wet season. Younger quails (≤10 and 11-22 weeks) had higher fertility and hatchability than older ones (23-34 and 35-52 weeks). Early embryo mortality also increased with age. Fertility and hatchability of eggs from caged birds was 89.54 and 62.34% as compared to 54.93 and 37.35% from deep litter reared birds and hatchability of fertile eggs was 69.63 and 67.96% respectively. Fertility and hatchability was highest (92.15 and 71.48%) for birds of ratio 1:3 and least for 1:5 (19.60 and 10%). Breeders that weighed 181-200 g had the highest hatchability (79.22%) and ≤140 g the least (60.83%). In contrast, breeder's with weights ≤ 140 g had the highest late embryo mortality (20%) and 141-160 g the least (9.67%). Light brown quails had lower hatchability of total and fertile eggs (23.71% and 35.71%) as compared to wild type or normal colored ones (52.04% and 69.84%). Light brown, however, had higher (P<0.05) early and late embryo mortalities (21.43% and 35.71%) than wild type (10.0% and 11.77%). It can be concluded from this study that for optimum fertility and hatchability, Japanese quail should be reared in cages at a mating ratio of 1:3 male to female.

Effects of desiccation of seeds in nine species with morphophysiological dormancy on germination and embryo growth

Aims In species with morphophysiological seed dormancy (MPD), little is known about the effects of desiccation of imbibed seeds on embryo growth and germination. We studied seed responses to dehydration in nine species with different levels of MPD. Methods For each species, a control test was conducted by keeping seeds permanently hydrated and exposed to the optimal stratification-incubation sequence to promote embryo growth. Simultaneously, tests were run in which seed stratification was interrupted for 1 month by desiccation at room temperature. Important Findings In Clematis vitalba and Ribes alpinum, with nondeep simple MPD, desiccation affected neither embryo growth nor seed viability, but the desiccation led to a decrease of germinative ability in R. alpinum by 16%. The seeds of Narcissus pseudonarcissus subsp. munozii-garmendiae, with deep simple epicotyl MPD, tolerated desiccation in different embryo growth stages, but their germinative ability decreased slightly. The response of species with complex levels of MPD to desiccation was more variable: Delphinium fissum subsp. sordidum, with intermediate complex MPD, and Anthriscus sylvestris and Meum athamanticum, both with deep complex MPD, tolerated desiccation. In contrast, Ribes uva-crispa with nondeep complex MPD, Lonicera pyrenaica with intermediate complex MPD, and Chaerophyllum aureum with deep complex MPD, had diminished germination ability by desiccation. Although seeds of the species with simple levels of MPD tolerated desiccation, those of some species with complex levels were also highly tolerant. Thus, desiccation did not induce secondary dormancy in late embryo growth stages. The desiccation tolerance of imbibed seeds of most of the nine species may show their adaptability to climate change in the Mediterranean region.

Methylation: An Ineluctable Biochemical and Physiological Process Essential to the Transmission of Life

Methylation is a universal biochemical process which covalently adds methyl groups to a variety of molecular targets. It plays a critical role in two major global regulatory mechanisms, epigenetic modifications and imprinting, via methyl tagging on histones and DNA. During reproduction, the two genomes that unite to create a new individual are complementary but not equivalent. Methylation determines the complementary regulatory characteristics of male and female genomes. DNA methylation is executed by methyltransferases that transfer a methyl group from S-adenosylmethionine, the universal methyl donor, to cytosine residues of CG (also designated CpG). Histones are methylated mainly on lysine and arginine residues. The methylation processes regulate the main steps in reproductive physiology: gametogenesis, and early and late embryo development. A focus will be made on the impact of assisted reproductive technology and on the impact of endocrine disruptors (EDCs) via generation of oxidative stress.

FMRF Gene Expression in the Nervous System of the Squid Doryteuthis Pealei* Hatchling

FMRFamide is a neuropeptide that is widely distributed in invertebrates and known to be involved in many physiological functions. Previously we noted marked differences in expression of the fmrf gene in the stellate ganglion of Doryteuthis pealei* compared to the central nervous system. In this study we aimed to examen the brain systems of Doryteuthis pealei* for the presence and distribution of fmrf-expressing cells and fiber networks. Late squid embryos and hatchlings were examined by in situ hybridization and immunohistochemistry in whole mounts and tissue sections. All central lobes contained limited numbers of scattered neurons expressing fmrf, but the FMRFamide-containing fiber systems were abundant and extensive, mostly present in the neuropil of lobes. Main clusters of neurons were located in the magnocellular and chromatophore lobes of the posterior subesophageal mass (PSM), and in dorsal aspects of the basal lobe (BL). Dense FMRFamide-immunoreactive fibers were particularly seen in the optic lobe (OL), medial and posterior supraesophageal masses (MSM and SPM) often with a commissural organization. The data show that the central lobes of Doryteuthis pealei hatchlings have a matured FMRFamide system organized in a limited number of centers, but with widely distributed efferents. This suggests that FMRFamide neurons are already functionally engaged in the late embryo. The localization indicates that control of chromatophores and fin movement are amongst these functions.

Comparative Transcriptome Analysis for Understanding Predator-Induced Polyphenism in the Water Flea Daphnia pulex

The crustacean Daphnia pulex is one of the best model organisms for studying inducible defense mechanisms due to their inducible morphology in response to the predator Chaoborus larvae. In this study, multiple developmental stages of D. pulex were exposed to C. flavicans larvae and transcriptome profiles of samples from late embryo to fifth instar were sequenced by the RNA-seq technique to investigate the genetic background underlying inducible defenses. In comparison, differentially expressed genes between defensive and normal morphs were identified, including 908 genes in late embryo, 1383 genes in the first-third (1–3) instar, and 1042 genes in fourth-fifth (4–5) instar. Gene ontology enrichment analysis showed that structural constituents of the cuticle and structural molecule activity genes were prominent up-regulated genes in late embryos. Down-regulated genes in late embryos and 1–3 instar comprised metabolic process, hydrolase activity, and peptidase activity gene classes. Pathway analysis indicated that small molecule neurotransmitter pathways were potentially involved in the development of inducible defenses. The characterization of genes and pathways in multiple developmental stages can improve our understanding of inducible defense responses of D. pulex to predation at the molecular level.