Evolution of chorion structural genes and regulatory mechanisms in two wild silkmoths: A preliminary analysis

Summary We report a preliminary analysis of structural and regulatory evolution of the A and B chorion gene families in two wild silkmoths,Antheraea pernyi andAntheraea polyphemus. Homospecific and heterospecific dot hybridizations were performed between previously characterizedA. polyphemus complementary DNA clones and total or stage-specific follicular mRNAs from the two species. The hybridization patterns indicated substantial interspecies changes in the abundance of corresponding mRNA sequences (heteroposic evolution) without substantial changes in their developmental specificities (heterochronic evolution). In addition, the proteins encoded in the two species by corresponding mRNAs were determined by hybrid-selected translation followed by electrophoretic analysis. The results suggested that the proteins evolve in size, presumably through internal deletions and duplications.     

红腹锦鸡和白腹锦鸡卵壳的超微结构

本文报道了锦鸡属——白腹锦鸡和红腹锦鸡卵壳的气孔、外壳膜、锥体层、木栅层的超微结构。并对两者的卵壳进行了比较。     

白额鹱卵壳的扫描电镜观察

本文报道白额鹱卵壳的壳膜、孔锥层、海绵层、表层等的超微结构,并对卵壳元素进行ＴＮ－５５００能谱分析。     

八种鸡形目鸟类卵壳及壳膜超微结构观察

８种鸡中,高原山鹑卵壳仅由乳突层和栅栏层构成,缺少护膜层,表面无裂纹,外气孔开放。其它种类由乳突层、栅栏层和护膜层构成,表面有裂纹、外气孔有覆盖。栅栏层都有与飞翔相适应的气泡,飞翔能力强,速度快的种类产卵壳气泡密度高的卵。     

Twisted β-pleated sheet: the molecular conformation which possibly dictates the formation of the helicoidal architecture of several proteinaceous eggshells

Evidence from X-ray diffraction, laser-Raman spectroscopy, secondary structure prediction, freeze-fracturing, conventional electron microscopy and Fourier analysis suggests that the helicoidal structure of the silkmoth eggshell (chorion) is created by protein molecules, most probably in a twisted β-pleated sheet conformation. It is proposed that this conformation also dictates the formation of the helicoidal architecture of other proteinaceous eggshells; apparently, it may also play an important role in the formation of the helicoidal architecture in other biological systems with protein components.     

In vitro development of theDrosophila chorion in a chemically defined organ culture medium

Summary TheDrosophila chorion is produced normally in isolated follicles in Robb's chemically defined culture medium. The complex architecture of the shell developed in vitro from follicles as young as early stage 10 is completely normal morphologically. In addition, the time required for in vitro development closely approximates that observed for in vivo development. Comparisons of insect culture media developed by Robb, Grace, Schneider, and Echalier show large variations in their ability to supportDrosophila chorion development.     

Crosslinking of theDrosophila chorion involves a peroxidase

Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components.     

Differential label‐free quantitative proteomic analysis of avian eggshell matrix and uterine fluid proteins associated with eggshell mechanical property

Eggshell strength is a crucial economic trait for table egg production. During the process of eggshell formation, uncalcified eggs are bathed in uterine fluid that plays regulatory roles in eggshell calcification. In this study, a label‐free MS‐based protein quantification technology was used to detect differences in protein abundance between eggshell matrix from strong and weak eggs (shell matrix protein from strong eggshells and shell matrix protein from weak eggshells) and between the corresponding uterine fluids bathing strong and weak eggs (uterine fluid bathing strong eggs and uterine fluid bathing weak eggs) in a chicken population. Here, we reported the first global proteomic analysis of uterine fluid. A total of 577 and 466 proteins were identified in uterine fluid and eggshell matrix, respectively. Of 447 identified proteins in uterine fluid bathing strong eggs, up to 357 (80%) proteins were in common with proteins in uterine fluid bathing weak eggs. Similarly, up to 83% (328/396) of the proteins in shell matrix protein from strong eggshells were in common with the proteins in shell matrix protein from weak eggshells. The large amount of common proteins indicated that the difference in protein abundance should play essential roles in influencing eggshell strength. Ultimately, 15 proteins mainly relating to eggshell matrix specific proteins, calcium binding and transportation, protein folding and sorting, bone development or diseases, and thyroid hormone activity were considered to have closer association with the formation of strong eggshell.     

A note on pterosaur nesting behavior

Based on examination of eggshell structure and predicted vapor conductances in eggshells in recently described material from Argentina and China we conclude that pterosaurs buried their eggs. Egg-burying imposes theoretical restrictions on the distribution of pterosaurs, both geographically and spatially, raises the possibility of thermal sex determination and supports previous suggestions that they exhibited nesting fidelity. Some features associated with egg-burying, such as weight savings, are likely to have been fortuitous pre-adaptations for these flying reptiles, but others may have disadvantaged them relative to avian competitors or increased their vulnerability to extinction in a cooling climate.     

Effect of weight and storage time of broiler breeders’ eggs on morphology and biochemical features of eggs,embryogenesis, hatchability,and chick quality

The transfer of hatchability results obtained under experimental conditions to the commercial ground with a positive financial effect proves the value and usefulness of these data. On the other hand, finding results on commercial processes of broiler breeders’ egg incubation in the literature is challenging. The presented study aimed to determine the effects of egg weight and storage time on the physical, biochemical characteristics of hatching eggs, embryogenesis and hatchability in Ross 308 broiler breeders. On the laying day, the eggs were divided into four weight groups: S – small eggs (57–61 g), M – medium eggs (62–66 g), L – large eggs (67–71 g), and XL – extra-large eggs (72–76 g). The eggs were then stored for 3, 7, 14, and 21 days under controlled conditions. As the egg storage time increased, a decrease in the yolk quality (lower index) was observed. The highest Haugh units were found in eggs from the S and M groups. The cholesterol content of the M, L, and XL groups was lower on days 7, 14, and 21 as compared to that of eggs only stored for 3 days. Egg weight loss during incubation decreased with an increase in the egg weight. An extension of the egg storage time caused an increase in the loss of egg weight. On the 14th and 18th days of hatching, an increase in the eggshell temperature was noted with an increase in the weight of the egg. The eggs stored for 7 days were characterised by the highest shell temperature on each day. The highest hatchability percentage was recorded for the M group. The hatchability rate decreased with the prolongation of the storage time, while the number of crippled chicks after hatching increased. The results confirmed that the increased weight of the eggs and prolonged storage time (14 and 21 days) increased the weight and decreased the length of the newly hatched chicks, respectively. Chicks from the heaviest eggs and those stored for 14 and 21 days showed poor results on the Pasgar score® test. The observations indicate the need to adopt various (of those available) methods to assess the quality of newly hatched chicks in hatcheries in order to produce high-quality broiler chickens. The results also indicate that prolonged egg storing beyond 14 days may affect the thyroid hormone economy during the hatching of chicks, especially in the XL group.