Intraguild Predation in Heteroptera: Effects of Density and Predator Identity on Dipteran Prey.

In tropical freshwaters, different species of water bugs (Heteroptera) constitute a guild sharing similar prey resources including chironomid and mosquito larvae. Assuming possibilities of intraguild predation (IGP) among the constituent members, an attempt was made to evaluate the effects of prey and predator density on the mortality of mosquito and chironomid larvae (shared prey), using Laccotrephes griseus Guérin-Méneville (Hemiptera: Nepidae) and Ranatra filiformis Fabricius (Hemiptera: Nepidae) as IG predators and Anisops bouvieri Kirkaldy (Hemiptera: Notonectidae) as IG prey. The predation on mosquito and chironomid larvae varied with the density and combinations of the predators. When present as conspecific IG predators, L. griseus exhibited greater effect on the prey mortality than R. filiformis. The effects on shared prey suggest that the two predators are not substitutable in terms of the effect on the shared prey mortality. The mortality of A. bouvieri (IG prey) at low shared prey density was significantly different (p < 0.05) from high shared prey density. In view of predatory effect of the heteropteran predators on the dipteran larvae, the results suggest possible interference by the presence of A. bouvieri as an intermediate predator. It seems that the presence of heteropteran predators including A. bouvieri as IG prey may benefit the dipteran prey under situations when the density is low in tropical waters. The intensity of the predatory effect may differ based on the species composition at IG predator level. For mosquito biological control, the interactions between the predators may not be substitutable and are independent in their effects.

Fibroblast growth factor receptors and regeneration of the eye lens.

If the eye lens of the adult newt, Notophthalmus viridescens, is removed, a new lens will regenerate and only from the dorsal, not the ventral, iris. The source, pigmented epithelial cells, would normally no longer divide, but upon lentectomy they do re-enter the cell cycle and form lens. The cause for this capability is unknown, but the mitogenic Fibroblast Growth Factors and their receptors may be involved. We have demonstrated that FGF receptors are present and operative in lens regeneration, since receptor-directed mitotoxins inhibit regeneration; heterogeneity and differential density in FGF-binding and receptor localization in iris sectors is also present. We propose that the spatial distribution of FGF receptors, especially the amphibian homolog of FGFR-3, is important in initiation of regeneration of eye lens.

Presence and foveal enrichment of rod opsin in the "all cone" retina of the American chameleon.

The retinal photoreceptors of the eye of the American chameleon, Anolis carolinensis, have been considered to be exclusively cones. Its retina is unusual for possessing two foveas (areas associated with heightened visual acuity), with the major, central fovea deeply incised and very densely packed with photoreceptors. Immunoblotting and light- and electron microscopic-immunocytochemistry, using several opsin monoclonal antibodies previously found specific for rods, demonstrated the presence and localization of this protein in the Anolis retina. This visual pigment appears sparsely in a subpopulation of photoreceptors in the periphery but overwhelmingly in the central fovea. Complementary results with cone-specific antibody and lectin binding corroborated this spatial organization. These results, as well as those with geckos, suggest that photoreceptor morphology is not an accurate guide among the lacertilians to visual pigment content, and that this phylogenetic grouping may constitute a crossroads in vertebrate photoreceptor evolution.

Ontogeny of alpha-crystallin polypeptides during the lens development of a mutant mouse.

The ontogeny of alpha A, alpha B and alpha Ains polypeptides of the alpha-crystallin was investigated by the indirect immunofluorescence staining method with antibodies directed against these three polypeptides in a mutant mouse strain called dyl (27). In this strain cataractogenesis starts around day 16 of lens development but the early development of the lens and the ontogeny of lens crystallins do not differ from the normal genotype (29). The polypeptides were fractionated from normal adult Swiss albino mice total native alpha-crystallin by SDS gel electrophoresis, extracted, lyophilized and injected into young rabbits for production of the antibody. The isolated polypeptides were controlled by SDS gel re-electrophoresis and the antibodies were tested against rat lens native alpha-crystallin by immunoblotting. alpha A and alpha Ains antibodies cross reacted, while alpha B did not show any cross reaction. Results presented here show that alpha A and alpha B appear simultaneously while alpha Ains was detectable at a later stage of lens development. These results are discussed.

Ontogeny of alpha A and alpha B crystallin polypeptides during Rana temporaria lens development.

The ontogeny and localization of alpha A and alpha B polypeptide chains of alpha-crystallin were investigated in the developing lens of Rana temporaria, an anuran amphibian, using the indirect immunofluorescence staining method with heterologous antibodies directed against these two polypeptides. alpha A and alpha B crystallins are primary gene products and are translated by different mRNAs in mammals. Although they show about 6000 amino-acid sequence homology (Bloemendal, 1977), the alpha A cDNA of rat and mouse does not hybridize to alpha B mRNA (Dodemont et al., 1981; King and Piatigorsky, 1983). Antigenically too, alpha A and alpha B polypeptides have been shown to be different. These two polypeptides were isolated from mouse lens native alpha-crystallin by SDS-gel electrophoresis and were injected into young rabbits to raise antibodies. These antibodies were tested by immunoblotting against R. temporaria total lens soluble proteins before their use in the present investigation. Results presented here show that in the developing lens of R. temporaria, alpha A appears earlier than alpha B, suggesting a differential gene activation. In addition, these two polypeptides could not be detected either in the developing lens epithelium or in the epithelium of young froglets (2-3 weeks post-metamorphosis).

Ontogeny of the 35K epsilon crystallin during Rana temporaria lens development.

Epsilon is a recently described eye lens protein from Rana temporaria, an anuran amphibian. It is oligomeric with a subunit M.W. of 35K. The cDNA coding for 35K E- in frog lens does not show any homology with cDNA's coding for alpha-, beta-, gamma-, and delta-crystallins. Immunologically, it also does not react with antibodies directed against alpha-, beta-, and gamma-crystallins. The ontogeny of this 35K E-protein has been investigated in R. temporaria lens development by the indirect immunofluorescence staining method with an antibody specific for the 35K E-protein. The purity of the isolated 35K protein and the specificity of the antibody were controlled by Tris-SDS gel electrophoresis and immuno-blotting, respectively. The first positive immunofluorescence reaction was observed in the inner cell wall of a stage V lens. In the external layer/epithelium the reaction was first detected in a single cell of a stage VII lens. Additional positive cells in the external layer/epithelium were detected at an early state VIII and the reaction appeared to be patchy. This type of patchy reaction was also observed in the epithelium of froglet (sub-adult) eye lens.

Ontogeny of the 38K epsilon-polypeptide during lens development of the duck Anas platyrhynchos.

The epsilon-crystallin polypeptide is a recently described protein in the eye lens of the peking duck, Anas platyrhynchos. It does not cross react with alpha-, beta-, delta-, and gamma-crystallins. It has a molecular weight of 120K and consists of 3 identical 38K polypeptides. It is found in some reptiles and birds. The ontogeny of this polypeptide has been investigated in the developing A. platyrhynchos lens via the indirect immunofluorescence staining using a homologous antibody. The 38K polypeptide was extracted from 13% Tris-SDS acrylamide gels, lyophilized and injected into a young rabbit to raise an antibody. The purity of the isolated 38K polypeptide and and the specificity of the antibody were checked by Tris-SDS gel electrophoresis and immunoblotting, respectively. The first positive reaction is detected at 80 h (stage 18) incubated lens. It is confined to a few elongating early primary fibres. Until the 9th day of development the reaction is confined to the primary and secondary lens fibres. The first positive reaction in the annular pad area is observed in the "day 10" lens. In the anterior epithelium the first positive reaction is detectable in the "day 12" lens. At the beginning it is confined to a few cells in the center of the epithelium and gradually the reaction spreads to other cells. A strong and uniform reaction in the entire epithelium is noted for the first time in the lens of a just-hatched duckling. The 38K epsilon-polypeptide is detectable after the alpha-, beta-, and delta-crystallins, which, in the duck, appear simultaneously from 66 h (stage 15/16).

Immunohistochemical studies of lens crystallins in the dysgenetic lens (dyl) mutant mice.

The lens in the dyl mutant mice shows a persistent lens-ectodermal connection as well as degeneration and extrusion of lens materials after the initial differentiation of the fibres. Immunohistochemical investigation of the ontogeny of the lens crystallins in this developing mutant lens has been carried out using the indirect immunofluorescence staining method with antiserum to adult mouse lens total soluble proteins. The results have been compared with those for coisogenic normal lens used as a control. In both, the first positive reaction was detectable at identical stages of lens development. A rapid increase in the intensity of fluorescence, most marked in the elongating fibre progressing through the equatorial region to the epithelium, was recorded in the mutant as well as in the normal lens. However, the stalk leading to the lens epithelium did not show any reaction. Appearance of vacuoles in the lens nucleus and cortex marked the beginning of degeneration of fibres which otherwise showed strong fluorescence. This was followed by extrusion of lens crystallin materials through the stalk. As a result, the lens became increasingly reduced and malformed but the surviving cells making up the vestigeal lens in the adult showed positive immunofluorescence. The results demonstrate that despite a failure of lens-ectoderm separation in the mutant mice, the ontogeny of the lens crystallins and differentiation of the lens up to a certain stage of development follow an apparently normal course before the commencement of cataractous degeneration.

Ontogeny and localization of the alpha-, beta-, and delta- crystallin antigens during lens development in mallard embryos.

The ontogeny of alpha-, beta-, and delta-crystallin antigens in the developing lens of mallard (Anas platyrhynchos) was investigated by indirect immunofluorescence using specific antibodies to mallard alpha-, beta-, and delta- crystallins raised in rabbits. The IgG fraction from each antiserum was isolated by affinity chromatography usign Protein A Sepharose CL-4B. Fluoresceinee (FITC) or rhodamine (TRITC) conjugated goat anti rabbit (GAR) gamma-globulin was used as the secondary antibody. The results show that alpha-, beta-, and delta-crystallins appear simultaneously in the developing mallard lens and are detectable from 66 hr (stage 15/16). This situation is different from the chick where delta- is known to appear first followed by beta-, and alpha-. This could be due to species variation. In the epithelium, however, as in the chick, delta- emerges first followed by beta-, and alpha- but rather late when compared with the chick and this seems probably due to a difference in the incubation time between the two species. Results from immunofluorescence and Tris-SDS gel electrophoresis demonstrate that alpha A subunit of the alpha-crystallin appears much earlier than the alpha B subunit. We also found that the newly discovered epsilon-crystallin (18) appears long after the three major crystallin classes.

Ontogeny and localization of the alpha, beta, and gamma crystallins in newt eye lens development.

The alpha-, beta-, and gamma-crystallins, proteins characteristic for the vertebrate eye lens, have been localized in the developing lens of Notophthalmus viridescens, the eastern spotted newt. Using the immunofluorescence technique, antibodies to the alpha-, beta-, and gamma-crystallin classes were applied to tissue sections through the eye region of developing N. viridescens embryos, Harrison (external) Stages 30 to 46+. beta-Crystallins were the first of the crystallins to appear in a few cells of the lens vesicle even before the lengthening of the prospective primary fiber cells. gamma-Crystallins were first detectable at a slightly more advanced stage in the prospective primary fibers, and alpha-crystallins in a few cells of the beginning primary fiber area. The external layer/epithelium was negative for beta-crystallins until late in lens morphogenesis, and alpha- and gamma-crystallins could not be detected in these cells at any time. This, the first use in amphibia of homologous antibodies specific for the crystallin classes, makes clear that phylogenetic differences exist as to the primacy and relevance of specific crystallins to events during morphogenesis of the eye lens.

Embryonic appearance of alpha, beta, and gamma crystallins in the periodic albinism (ap) mutant of Xenopus laevis.

The appearance of the crystallins during lens development in the periodic albinism (ap/ap) mutant of Xenopus laevis has been studied. Using antibodies specific for total crystallins, alpha + beta crystallins, and gamma crystallins in the immunofluorescence technique, the first positive reaction for all could be demonstrated in the Nieuwkoop-Faber Stage 31 lens rudiment. The antibody to alpha + beta crystallins exhibited differences in intensity from cell to cell in the early rudiment, while the reaction to the other antibodies was uniform throughout the rudiment. As lens differentiation progressed, immunofluorescence was restricted in all cases to the lens fiber area, up to and including Nieuwkas positive, however, for total lens crystallins. These results are at variance with earlier studies on lens development and the crystallins in wildtype (+/+) X. laevis, where a positive reaction for gamma and total crystallins could be detector total lens crystallins. That this divergence in the mutant is due to a pleiotropic effect or directly to the inductive failure of the endomesoderm to initiate melanogenesis, is discussed.

Ontogeny of lens crystallins in marine cephalopods.

The ontogeny of the lens crystallin antigens throughout development of three marine cephalopod embryos, Loligo vulgaris, Sepia officinalis and Octopus vulgaris has been investigated using the indirect immuno-cytochemical staining against respective homologous anti-total lens protein antiserum. The cellular mechanism of lens development appears to be the same in all species investigated and so does the ontogeny of the lens crystallins. The first positive immuno-fluorescence reaction appears simultaneously and in equal intensities over the lens and lentigenic area confirming the relationship between the two.

Eye lens development and gamma crystallins in Discoglossus pictus (Anura).

The ontogeny and localization of the gamma crystallins in Discoglossus pictus lens development has been determined. Using antibody specific for amphibian gamma crystallins in the immunofluorescence technique, it was found that gamma crystallins first appear in primary lens fibre cells in the lens rudiment, and continue to be restricted to the fibre area as lens development progresses. Thus the role of gamma crystallins as indicators of a differentiated state remains constant in amphibian evolution, having been demonstrated in the most archaic anuran superfamily, as well as in others more recently evolved.