Egg hatching of two locusts,Schistocerca gregaria and Locusta migratoria,in response to light and temperature cycles

The present study showed that the eggs of the desert locust, Schistocerca gregaria, and the migratory locust, Locusta migratoria, responded to photoperiod by hatching when placed on sand in the laboratory. S. gregaria mainly hatched during the dark phase and L. migratoria during the light phase. The importance of light as a hatching cue depended on the magnitude of the temperature change during the thermoperiod; photoperiod played a more important role in the control of hatching time in both species when the magnitude of the temperature change was small. In addition, the eggs of the two species that were covered with sand did not respond to photoperiod and hatched during both the light and dark phases, indicating that light did not penetrate through the sand. Because locust eggs are normally laid as egg pods and a foam plug is deposited between the egg mass and the ground surface, we tested a possibility that naturally deposited eggs perceived light through the foam plug. The eggs that were deposited and left undisturbed in the sand hatched during the light and dark phases at similar frequencies. These results suggest that the eggs of both locust species responded to light and controlled their hatching timing accordingly but would not use light as a hatching cue in the field. The evolutionary significance of the ability of eggs to respond to light in these locusts was discussed.     

Early ontogeny of Labeotropbeus Ahl, 1927 (Mbuna,Cichlidae, Lake Malawi), with a discussion on advanced protective styles in fish reproduction and development

Synopsis With yolk as a food source, development of Labeotropheus takes place in the buccal pouch of the female until such time as juveniles are formed. Hatching from the vitelline membrane occurs early, after 6 days of incubation, and the eleutheroembryo develops without metamorphic stages directly into a juvenile, forming advanced structures like fins, skeleton and pigments, at a time when a large yolksac is still present. A strong circulatory network on the yolk and anal fin fold, and a yellow carotenoid pigment provide the oxygen supply within the closely packed buccal pouch. A relatively large self-sufficient juvenile, 14% of the adult fish size, is released from the mother's mouth 31 days after fertilization. The evolution of advanced hiding styles in reproductive guilds of fishes is discussed and ends with a speculation that the Latimeria, having had more geological time to refine its hiding style, releases fully developed young, 25 to 30% the size of the adult fish. The advanced style of hiding eggs is accompanied not only with fewer, larger eggs, but also by a successive increase in yolk density in terms of nutrients and respiratory pigments; these in effect determine the size of the released juvenile.     

Glucose metabolism during embryogenesis of the hard tick Boophilus microplus

Glucose metabolism plays an essential role in the physiology and development of almost all living organisms. In the present study we investigated glucose metabolism during the embryogenesis of the hard tick Boophilus microplus. An increase in glucose and glycogen content during the embryonic development of B. microplus was detected and shown to be due to the high enzyme activity of both gluconeogenesis and glycolytic pathways. Glucose 6-phosphate (G-6P), formed by hexokinase, is driven mainly to pentose-phosphate pathway, producing fundamental substrates for cellular biosynthesis. We detected an increase in glucose 6-phosphate dehydrogenase and pyruvate kinase activities after embryo cellularization. Accumulation of key metabolites such as glycogen and glucose was monitored and revealed that glycogen content decreases from day 1 up to day 6, as the early events of embryogenesis take place, and increases after the formation of embryo cellular blastoderm on day 6. Glucose and guanine (a sub-product of amino acids degradation in arachnids) accumulate almost concomitantly. The activity of phosphoenolpyruvate carboxykinase was increased after embryo cellularization. Taken together these data indicate that glycogen and glucose, formed during B. microplus embryogenesis after blastoderm formation, are produced by intense gluconeogenesis.     

A system to efficiently maintain embryonic lethal mutations in the flour beetle Tribolium castaneum

 Due to its small size, short life cycle, and easy maintenance, the flour beetle Tribolium castaneum is well suited for the genetic analysis of development. One drawback of Tribolium as a genetic system is, however, the difficulty of keeping embryonic lethal lines. Presently, only few lethal mutations can be kept as balanced stocks. Therefore, heterozygous carriers must be identified anew in every generation in order to maintain a recessive embryonic mutation. To alleviate this problem we have devised a block system that allows the simultaneous processing of many mutant lines or test crosses for visual inspection of larval cuticle phenotypes. Using this technique, one person can maintain about 100 embryonic lethal stocks, which makes feasible the thorough genetic analysis of embryogenesis in this species. Received: 4 November 1998 / Accepted: 7 February 1999     

Zur Struktur der Kolibri-Eischale

Zusammenfassung Die Eischalen der Trochilidae (Kolibris) sind an ihrer Oberfläche in spezifischer Weise zart aufgerauht: durch eine eigenartige Differenzierung der Stirnflächen ihrer Säulenprismen.

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The structure of Trochilidae egg shell

Summary Egg shells of Trochilidae are characterized by a special roughness of their surface: the frontal faces of their columnar prisms are uniquely differentiated.

     

The establishment of appropriate methods for egg-activation by human PLCZ1 RNA injection into human oocyte

Phospholipase C-zeta (PLCZ1), a strong candidate of egg-activating sperm factor, can induce Ca²⁺ oscillations and cause egg activation. For the application of PLCZ1 to clinical use, we examined the pattern of Ca²⁺ responses and developmental rate by comparing PLCZ1 RNA injection methods with the other current methods, such as cytosolic aspiration, electrical stimulation and ionomycin treatment in human oocytes. We found that the pattern of Ca²⁺ oscillations after PLCZ1 RNA injection exhibited similar characteristics to that after ICSI treatment. We also determined the optimal concentration of human PLCZ1 RNA to activate the human oocytes. Our findings suggest that human PLCZ1 RNA is a better therapeutic agent to rescue human oocytes from failed activation, leading to normal and efficient development.     

Divergent Proteome Patterns of Egg Albumen from Domestic Chicken,Duck, Goose,Turkey, Quail and Pigeon

To uncover a diversity of genetic and biological unknowns, a comprehensive and comparative proteomic analysis is performed on egg albumen of domestic chicken, duck, goose, turkey, quail, and pigeon with tandem mass tags quantification technology. In this study, a total of 148, 138, 150, 162, 183, and 179 proteins are identified in egg albumen of the above six species, respectively. Venn plots, PCA, and cluster analysis all reveal the highest similarity of protein composition between duck and goose (≈75%). Additionally, the six species have 52 proteins detected in common in the egg albumen. As revealed by GO and pathway analyses, the plausible functions of these highly conserved proteins are to provide a secure environment and prevent the early death of embryonic cells. Species‐specific proteins such as haptoglobin in pigeon, serpin‐like protein HMSD in duck, and ovodefensin in chicken are also screened and are likely associated with species‐dependent biological processes. Furthermore, Enzyme Code analysis indicated egg albumen have abundant enzyme activity, with hydrolases accounting for more than half of the total enzymes. This study is the first to provide the proteome profiles of egg albumen for the major poultry species, which will be instructive for the understanding of species‐specific biological problems with egg albumen.     

Incorporation of mouse zona pellucida proteins into the envelope of Xenopus laevis oocytes

 All vertebrate eggs have extracellular matrices, referred to as the zona pellucida in Mus musculus and the vitelline envelope in Xenopus laevis. The mouse zona, composed of three sulfated glycoproteins (ZP1, ZP2, ZP3), is critical for fertilization and early development, and mice lacking a zona pellucida produce no live offspring. The primary structures of mouse ZP1 (623 amino acids), ZP2 (713 amino acids) and ZP3 (424 amino acids) have been deduced from full-length cDNAs, but posttranslational modifications result in mature zona proteins with molecular masses of 200–180 kDa, 140–120 kDa, and 83 kDa, respectively. The vitelline envelope forms a similar structure around Xenopus eggs and contains three glycoproteins that are structurally related (39–48% amino acid similarity) to the three mouse zona proteins. To investigate whether the structural semblances are sufficient to allow incorporation of the mouse zona proteins into the Xenopus vitelline envelope, capped synthetic mRNAs encoding ZP1, ZP2, and ZP3 proteins were injected into the cytoplasm of stage VI Xenopus oocytes. After 20 h of incubation the oocytes were harvested, and posttranslationally modified zona proteins were detected with monoclonal antibodies specific to mouse ZP1, ZP2, and ZP3. The oocytes were imaged with confocal microscopy to detect individual zona proteins in the extracellular matrix of the oocytes, and this localization was confirmed biochemically. Thus the mouse zona proteins appear to have been sufficiently conserved through 350 million years of evolution to be incorporated into the extracellular envelope surrounding Xenopus eggs. Received: 5 January 1999 / Accepted: 12 February 1999     

Maternal body volume constrains water uptake by lizard eggs in utero

1. Flexible shelled eggs of squamate reptiles normally take up substantial amounts of water, and swell accordingly, during development. However, most water uptake occurs after oviposition, beginning immediately or soon after oviposition, and water uptake is severely restricted in eggs that are retained in utero past the normal time of oviposition.
2. These observations suggest that some aspect of retention in the oviductal environment limits the amount of water eggs can absorb prior to oviposition.
3. This paper presents evidence, from two species of Sceloporus lizard, supporting the hypothesis that limited space within the mother's body cavity physically constrains the ability of eggs to expand, and thereby their ability to absorb water. When adjusted for maternal body size, the water content of a female's clutch of eggs is negatively correlated with the dry mass of her clutch (the space available in the body cavity is finite, and thus a greater dry mass content leaves less volume for water).
4. If such a constraint on water uptake is widespread, it can have important implications for our understanding of the evolution of viviparity, the costs of reproduction, and the determinants of reproductive output in squamate reptiles.     

Yolk lipids and their fatty acids in the wild and captive ostrich (Struthio camelus)

A comparative study has been made of the major lipid fractions and their fatty acid compositions in the yolk of eggs from ostriches under wild and farmed conditions. There were no differences in the lipid contents and proportions of the lipid fractions between the two groups of yolks. In both groups of yolks triacylglycerol and phospholipid were the major fractions. In the eggs from the wild ostriches, all the lipid fractions displayed substantial concentrations of C18 polyunsaturated fatty acids, triacylglycerol being particularly rich in linolenic acid and phospholipid rich in linoleic acid; phospholipid displayed substantial concentrations also of C20 and C22 polyunsaturates. There were considerable differences in the fatty acid compositions between the yolks. Those from the farmed birds displayed lower proportions of C18 polyunsaturates, particularly linolenic acid, throughout the lipid fractions. Compensatory increases were displayed most obviously in the concentrations of oleic acid and palmitoleic acid as well as other acids. The distinctive and extensive changes in fatty acid composition, particularly relating to the polyunsaturates, are discussed with respect to overall dietary requirements and specificities for embryo metabolism and possible effects on reproductive performance.