Some aspects of osmotic biology of the freshwater leech,Poecilobdella viridis (Blanchard)

Ability of the freshwater leech, Poecilobdella viridis to withstand osmotic changes was investigated by following the fluctuations of the body weight in tap-water and in different salt concentrations. The salinity tolerance limit (lethal salt concentration) of this leech was found to be 1.54% NaCl which equilibrates approximately 51.359% sea-water. There was a significant weight loss in P. viridis when kept in both, hypo- and hypertonic media. It is concluded that volume regulation (through weight changes) was slight in hypotonic media whereas in hypertonic media there was an incessant decline in body weight. Adaptive significance of these findings is discussed.     

Involvement of neurohormone in regulation of oxygen consumption in the marine gastropod,Onchidium verruculatum

Ablation of whole central nervous system (CNS) or pleurovisceral (PV) ganglia significantly inhibited O₂ uptake, after 4 hr through 24 hr of the operation over sham controls. Replacement of PV in PV-less animals restored their metabolic rates to the normal level. O₂ consumption of normal animals is significantly augmented by the macerates of CNS and PV, but not by cerebral and pleural ganglia, and body muscles. Reserpine was ineffective in lowering the O₂ uptake of PV-removed animals unlike in normal, intact individuals. The possible implication of a neurohormone originating from PV ganglia controlling whole body O₂ consumption, is discussed.     

Hormonal control of blood chloride in the marine pulmonate,onchidium verruculatum

A search for endocrinological factors inO. verruculatum revealed that three hours after right pleural ganglion extirpation blood chloride is significantly (P<0.01) sinked. Administration of right pleural ganglion homogenate (I gang/animal) into depleuralised snails significantly (P<0.001) enhances the blood chloride level after three hrs. Removal of the ganglia other than the right pleural provokes a significant (P<0.01) decline in blood chloride profile in these animals. However, replacement therapy either via homogenate injection or reimplantation of the particular ganglion into extrapleural ganglionectomised animals is ineffective in restoring the chloride levels. It is argued that only right pleural ganglia control blood chloride via vascular channels.     

Susceptibility of urea and uric acid levels to neurohormone influence in the freshwater pulmonate,lymnaea acuminata

Effects of pooled ganglionic extract on the urea and uric acid levels from blood, hepatopancreas, mantle and kidney of the pulmonate L. acuminata have been analysed. Blood urea and mantle uric acid were significantly (P<0.005 and P<0.05 respectively) increased following injection with pleuroparietalpedal-visceral (PPPV Complex) ganglia homogenate within 2 hrs. On the contrary hepatopancreas urea and kidney uric acid levels were significantly (P<0.00) lowered. Cerebral ganglia homogenate and boiled extract of PPPV complex did not provoke any significant change in urea and uric acid levels. It is advocated that (a) neurohormone(s) which is (are) heat-labile and originate from the PPPV complex, influence(s) the nitrogen end-products in these snails.     

Responses of the neurosecretory cells of the freshwater snail,Indoplanorbis exustus to hydrothermal stress

Changes in the neurosecretory cell cytology of I. exustus subjected to hypertonic saline (0.1 ml of 1.5%/snail) loading and thermal stress (35°C) for two hours, have been investigated. Of the two types of neurosecretory cells A and B that are present in the central nervous system (CNS) of I. exustus, striking changes were evident only in B cells. After both treatments, there was about 33% decline in NSM (Neurosecretory material) intensity. However, the nuclear diameter of B cells was significantly (P < 0.001) increased in the snails administrated with hypertonic saline unlike in those exposed to 35°C wherein significant (P < 0.005) decline was evident. The adaptive significance of the neuroendocrine system of I exustus is discussed in relation to hydrothermal stress.     

Effect of thermal acclimation on gametogenesis of the indian freshwater leech,Poecilobdella Viridis (Blanchard)

The effect of thermal acclimation for 15 days on the gametogenesis of Poecilobdella viridis was studied. Leeches conditioned at laboratory temperature (25.5°–27.5°C), when warm acclimated (32.0° ± 0.5° C), displayed a significant (p < 0.05) increase in the percentage of oocytes having a diameter of 12.5 µ and 15.0 µ and in the percentage of fully mature sperm clusters over the controls, whereas cold acclimation (10.0° ± 0.5°C) did not induce significant (p > 0.05) changes in the oocytes and sperm clusters. Thus it is concluded that in P. viridis temperature is of paramount importance in initiating gametogenesis.     

Roles of 5-hydroxytryptamine and dopamine as neurotransmitters eliciting release of erythrophorotropic hormones in the fiddler crab,Uca pugilator

This article reviews the endocrinological, pharmacological and biochemical evidence ascribing neurotransmitter roles for 5-hydroxytryptamine (5-HT, serotonin) in eliciting the release of red pigment-dispersing hormone (RPDH) and for dopamine (DA) in stimulating the release of red pigment-concentrating hormone (RPCH) in the fiddler crab, $\text{Uca pugilator}$. 5-HT produces red pigment dispersion in intact crabs, but only indirectly. Likewise, DA evokes red pigment concentration $\text{in vivo}$ but it has no effect on red chromatophores (erythrophores) in isolated legs. The data obtained with 5-HT and DA agonists and antagonists on red pigment translocation $\text{in vivo}$ and $\text{in vitro}$, are consistent with their neurotransmitter candidacies in evoking the release of these erythrophorotropic hormones.     

Localization of substance P-like,leucine-enkephalin-like,methionine-enkephalin-like,and FMRFamide-like immunoreactivity in the eyestalk of the fiddler crab,Uca pugilator

Summary The occurrence and distribution of substance P (SP)-like, methionine-(Met)- and leucine-(Leu)-enkephalinlike, and FMRFamide-like immunoreactivities were determined in the neuroendocrine complex of the eyestalk of the fiddler crab, Uca pugilator, by immunocytochemistry. SP-like immunoreactivity was found in the optic peduncle, sinus gland, medulla externa, medulla interna, lamina ganglionaris, and retinular cells. Met-enkephalin-like and Leuenkephalin-like immunoreactivity was observed in most of the retinular cells, optic peduncle, sinus gland, medulla terminalis, and lamina ganglionaris. However, Met-enkephalin-like, but no Leu-enkephalin-like, immunoreactivity was seen in the medulla terminalis X-organ. FMRFamide-like immunoreactivity could be seen in all parts of the eyestalk except in the sinus gland, lamina ganglionaris, and retinular cells. FMRF-amide-like activity was especially strong in the three chiasmatic regions connecting the optic ganglia. The possibility that these four peptides may function as neuroregulators in the fiddler crab is discussed.This investigation was supported in part by Grant No. PCM-8300064 from the National Science Foundation to MF and Biomedical Research Support Grant No. 2 SO7RRO5373 SUB from the University of Kansas Medical Center to LLV     

Effect of thermal stress on the neurosecretory cells of the freshwater prawn,macrobrachium kistnensis (Tiwari)

The brain and thoracic ganglion neurosecretory cells of the freshwater prawn, M. kistnensis displayed characteristic changes following 24 hr exposure to warm (31.0° ± 0.5°C) and cold (13.0° ±0.5°C) stress. A and B cells from the brain showed significant elevation in their nuclear diameters after warm and cold stress. Warm stress depressed whereas cold stress enhanced the neurosecretory material intensity of A cells. However, the intensity of B cells neurosecretory material remained unaltered following both treatments. On the contrary nuclear diameters of both A and B neurosecretory cell significantly decreased and an increment in neurosecretory material intensity was revealed in the thoracic ganglion of both warm and cold stressed prawns.