Production of embryos that are free of tough outer coats facilitates studies that are not possible with embryos surrounded by impenetrable envelopes. This report describes a new procedure for preventing formation of fertilisation membranes in the sea urchin (Lytechinus pictus) model. This procedure involves treating unfertilised eggs with the enzyme alpha-amylase, which cleaves alpha-1,4 glucosidic bonds in the vitelline layer. A major advantage of this method is that it is very well defined and completely controllable with alpha-amylase inhibitor. The results suggest that intact alpha-1,4 glucosidic bonds are essential for vitelline layer integrity required for formation of the fertilisation membrane. Eggs treated with alpha-amylase possessed the same surface lectin receptors as untreated eggs and, as shown by light and transmission electron microscopy, produced healthy, cleaving embryos that were free of fertilisation envelopes.

Vitellogenin (VTG) was isolated from the haemolymph of Penaeus vannamei by a three stepprocedure including ultracentrifugation, gel filtration and ion exchange chromatography. VTG wasused to raise polyclonal antibodies that were purified by ion exchange chromatography. A two stepcompetitive assay was developed in which VTG could be quantitated by its capacity to inhibit thebinding of antibody to the VTG previously adsorbed onto a solid phase. Sensitivity from equilibriumand from non-equilibrium assays was 41 and 2.3 ng/ml respectively. Estimates of within-assay andbetween-assay variabilities of standard curves were 4.2 and 9.6% respectively. The inhibition curves for dilutions of haemolymph from vitellogenic females, egg yolk extracts and purified vitellin (VTL) were parallel to the standard VTG curve, haemolymph from immature females and males showed no cross-reactivity. The antibodies directed against VTG recognize but partially VTL as shown by displacement curves. Recovery tests were near 100%. Thus the procedure was considered to be suitable for the measurement of haemolymphatic VTG. The VTG enzyme-linked immunosorbent assay (ELISA) developed in this study was validated by detecting physiological VTG changes in female shrimps after being fed squid extracts.

Two monoclonal antibodies (Mabs), that react in an enzyme linked immunoabsorbant assay, were generated against Aedes aegypti vitellin. One of these Mabs, VIIG9 that reacted predominantly with a 64 kDa component of Ae. aegypti yolk protein, also recognized 68 kDa and 66 kDa components in the yolk proteins of Culex sitiens and Cx. annulirostris, respectively. Mab VIIG9 has been used to detect vitellin or vitellin precursors in gravid female and non-blood fed nulliparous female mosquitoes as a possible age grading method. The presence of polyclonal and monoclonal antibodies to vitellin in the blood meal did not affect the fecundity of Ae. aegypti.