Seasonal effects of melatonin on ovary and plasma gonadotropin and vitellogenin levels in intact and pinealectomized catfish, Clarias batrachus (Linn).

Effects of daily administration of melatonin for 15 days were evaluated with respect to ovarian activities and plasma gonadotropin (GtH II) and vitellogenin (Vg) levels in intact (INT) and pinealectomized (Px) female catfish, C. batrachus, during preparatory (April), prespawning (May and June), spawning (July) and post-spawning (September) periods. Px (saline control groups) caused a stimulatory effect during preparatory (with respect to Vg synthesis and incorporation) and prespawning (with respect to Vg synthesis) periods whereas no effect was observed during spawning and post-spawning periods with respect to the reproductive parameters studied. During April, melatonin-treatment significantly decreased plasma GtH II levels and percentage of vitellogenic oocytes without any significant changes in plasma Vg levels and gonadosomatic index (GSI). During early prespawning period, in May, 50microg melatonin brought about a significant reduction in plasma GtH II levels in INT group, whereas 100microg caused a decrease in all parameters; on the other hand, in Px groups both dose levels proved to be inhibitory. In June (late prespawning period) melatonin-treatment could not bring about any change in GSI and plasma Vg levels compared to the control groups regardless of Px but plasma GtH II and mean number of yolky oocytes were significantly reduced in melatonin-treated INT group. During spawning period (July) melatonin inhibited the GSI, mean number of yolky oocytes and plasma GtH II levels without affecting plasma Vg levels. In September (post-spawning period), melatonin did inhibit both GSI and plasma GtH II levels. The results, thus, indicate that melatonin showed variable effects (inhibitory and/or no effect) to GSI, mean number of yolky oocytes and plasma Vg levels but a consistent inhibiton of plasma GtH II levels indicating that melatonin may control the reproduction by blocking the GtH II release from the pituitary via affecting the hypothalamo-hypophysial axis.

Characters that differ between diploid and haploid honey bee (Apis mellifera) drones

Diploid males have long been considered a curiosity contradictory to the haplo-diploid mode of sex determination in the Hymenoptera. In Apis mellifera, 'false' diploid male larvae are eliminated by worker cannibalism immediately after hatching. A 'cannibalism substance' produced by diploid drone larvae to induce worker-assisted suicide has been hypothesized, but it has never been detected. Diploid drones are only removed some hours after hatching. Older larvae are evidently not regarded as 'false males' and instead are regularly nursed by the brood-attending worker bees. As the pheromonal cues presumably are located on the surface of newly hatched bee larvae, we extracted the cuticular secretions and analyzed their chemical composition by gas chromatograph-mass spectrometry (GC-MS) analyses. Larvae were sexed and then reared in vitro for up to three days. The GC-MS pattern that was obtained, with alkanes as the major compounds, was compared between diploid and haploid drone larvae. We also examined some physical parameters of adult drones. There was no difference between diploid and haploid males in their weight at the day of emergence. The diploid adult drones had fewer wing hooks and smaller testes. The sperm DNA content was 0.30 and 0.15 pg per nucleus, giving an exact 2:1 ratio for the gametocytes of diploid and haploid drones, respectively. Vitellogenin was found in the hemolymph of both types of imaginal drones at 5 to 6 days, with a significantly lower titer in the diploids.

Immunological identification of two female-specific proteins from the plasma of Indian freshwater murrel, Channa punctatus (Bloch).

Existence of a non-phosphorylated female-specific protein (FS II), in addition to phosphorylated vitellogenin (FS I), in the plasma of murrel by exogenous administration of estradiol-17beta is reported. Polyspecific rabbit antibodies were raised against estrogen-inducible murrel plasma proteins. This antiserum was absorbed with normal male serum in order to obtain female-specific antiserum (FSAS). Radial immunodiffusion studies suggested that both the proteins (FS I and FS II) were present in the plasma of E2-treated and normal vitellogenic females and in the ovarian homogenate from gravid females, but absent in normal male plasma. Autoradiographic experiments demonstrated that phosphorus moiety was attached with FS I only. Further, immunoelectrophoretic analysis and peptide maps supported the observation that FS I and FS II were discrete, unrelated female-specific proteins.

Demonstration of two forms of vitellogenin in serum of estradiol-17 beta-treated Indian major carp, Labeo rohita.

Vitellogenin (Vg) synthesis was induced in the male and non-vitellogenic female Rohu, the Indian major carp, by estradiol-17 beta(E2) where effect was more in female. A crude preparation of Vg was isolated in the second peak after gel filtration on Ultrogel AcA 34 from the sera of vitellogenic female Rohu and E2-treated male and female Rohu. Estimation of alkali-labile phosphorus was shown to be used as an index of Vg. Native-PAGE analysis has revealed the presence of two forms of Vg (Vg1: 430,000 dalton and Vg2:240,000 dalton) in Vg fraction obtained after gel filtration as well as in the sera of E2-treated male and female Rohu. Immunological cross-reaction studies between antiserum to yolk protein and Vg fractions as well as the sera from E2-treated male and female Rohu further indicates the presence of two precipitin lines (not clearly visible as the two lines fused to form a thick line) suggesting the occurrence of two forms of Vg in the Rohu.

The effect of pH and metal chelators upon the sedimentation velocity of Odontophrynus americanus vitellogenin

In the tetraploid amphibian Odontophrynus americans the selective precipitation of vitellogenin by Mg2+ from plasma treated with ethylene diaminetetraacetic acid (EDTA) or ethylene bis (oxyethylenenitrilo)-tetraacetic acid (EGTA) is a pH-dependent phenomenon. Utilizing sucrose gradient centrifugation of whole plasma we have shown that under standardconditions (pH 7.0) the estimated apparent sedimentation coefficient of vitellogenin is 17s.At pH 8.0 and in the presence of EDTA or EGTA there is a decrease of the vitellogenin sedimentation coefficient.This behavior is restricted to vitellogenin as othewr plasma proteins show no alteration in their sedimentation coefficient after similar treatment. The treatment with EDTA at pH 8.0 also induces changes in the vitellogenin molecule which can be detected by partial proteolysis with chymotripsin A

Vitellin and vitellogenin characterization of Triatoma infestans and related species

La vitelogenina-vitelina (VG-VN) de Triatoma infestans es una glicolipoproteína con un peso molecular de 220 000, es una lipoproteína de alta densidad (1.18-1.2 gm/ml) con poca movilidad electroforética a pH 8.2. Hembras, machos, ninfas y huevos comparten numerosas proteínas pero ninguna de ellas es glicolipoproteica. La proteína común más importante posee un peso molecular de 43 000, es anódica y se encuentra a lo largo de todo el gradiente salino. Machos y hembras poseen una glicolipoproteína con una movilidad electroforética similar a l VG-VN, pero es una proteína de baja densidad. Otra VG-VN, catódica, no glicolipoproteica, se encuentra en huevos y hemolinfa de hembra. La VG-VN principal puede ser aislada por ultracentrifugación en gradiente de BrNa o por cromatografía en DEAE-celulosa. Varias especies dentro del género Triatoma demostraron identidad inmunológica entre sus VG-VN. Las hembras y los huevos de Panstrogylus megistus y las hembras, los huevos y los machos de Rhodnius prolixus poseen identidad inmunológica parcial con las VG-VN de T. infestans