The hypothalamo-hypophysial vascular relationship in Indian fresh-water goby, Glossogobius giuris (Ham.).920u.

The hypothalamo-hypophysial vascular relationship and intra-hypophysial vasculatisation have been described in order to understand the regulatory mechanism of hypothalamic control over the functions of the pituitary gland. In Glossogobius giuris, the disposition of the blood vessels in the head region is on typical teleostean pattern with certain modifications. The nucleus preopticus is supplied through the nucleus preopticus artery, a small blood vessel arising from the anterior branch of the posterior cerebral artery, whereas the pituitary gland receives blood through a pair of hypophysial arteries. The blood from the pituitary is drained off by the pituitary veins whch pour their blood into the supra-orbital sinus. The anterior cerebral vein after taking the blood from anterior part of the brain including the hypothalamus and the nucleus preopticus joins with the supra-orbital sinus. The hypothalamo-hypophysial portal system is absent in this fish. The saccus vasculosus receives blood from the posterior cerebral artery through a small blood vessel and is collected by a prominent saccus vasculosus vein which pours blood into the supra-orbital sinus before it joins the infra-orbital sinus to form the heat vein. There seems to be no physological connection between the saccus vasculosus and pituitary gland. The highly vascularised neurohypophysis interdigitate with the pars intermedia and extends upto the proximal pars distalis. The blood vessels are restricted to the neurohypophysial extensions only. However, in the rostral pars distalis the blood vessels are present but the neurohypophysis does not extend to this part. The blood capillaries enter the rostral pars distalis from the capillary network on the surface of pituitary gland along with the connected tissue covering of the pituitary. The neurohypophysis shows a greater vascularisation in comparison to that of the other glandular part of the pituitary gland. In the present study of Glossogobius giuris, though an extensive ramification of neurohypophysis occurs with the pars intermedia and the proximal pars distalis, the neurosecretory axons do not innervate the endocrine cells of the pituitary gland and the blood vessels are found restricted to the neurohypophysial extensions except that of the rostral pars distalis. The neuro-vascular way of hypothalamic control over the functions of the pituitary gland seems to be justified as the neurosecretory fibres have been found associated with the blood vessels.     

Histophysiology of the saccus vasculosus of the Indian freshwater goby Glossogobius giuris Ham. (Teleostei)

The author studied the structure and functions of the saccus vasculosus of the Indian freshwater goby Glossogobius giuris (Ham.). The saccus is ovoid, is localized on the ventral surface of the brain and is lodged between the inferior lobes. It consist of several loculi lined with coronet cells and is bathed with blood from surrounding sinusoids. The coronet cells are variably shaped and have a conspicous central nucleus. It is suggested that the purpose of the saccus vasculosus is to act as a storage site for carbohydrates to the brain. By converting glycogen to acid mucopolysaccharides, the coronet cells are involved in glycogen metabolism.     

Ultrastructural changes in testis of gobiid fish Glossogobius giuris (Ham) induced by fenthion

Pesticides are known to affect the testis in fishes and cause cytomorphological changes or gross physiological alterations due to changes in its histology, retard gonadotrophic secretions thereby causing regression of the gonads. Light and ultrastructural studies were made on control and fenthion treated testis, interstitial gland and sperms of G. giuris during spawning phase after exposing them to different sub-lethal concentrations (0.05, 0.25 and 0.5 ppm) fenthion for a short-term period (24, 48, 72 and 96 hr). The results indicated extensive cytotoxic damages in the testis including atrophy of testis, reduction in lipoidal material in the interstitial cell and degeneration of sperms. The alteration in histology of testis, interstitial cell and sperms progressively increased with the increase in the sub-lethal concentration of pesticides.     

Melanophore characteristics in a fresh-water teleost, Puntius conchonius (Ham.)

The present study is an attempt to determine the factors responsible for the melanophore pattern of the freshwater teleost, Puntius conchonius (Ham.) under normal background conditions (i.e., the existence of a large round black spot on the middle of the side above the posterior part of the anal fin and the dull shade of the rest of the body which is brownish on the dorsal part, referred here in the present study as the general body surface and silvery along the lateral and ventral part of the body). On the basis of nature of their branching pattern various morphological types of melanophores are classified in a scale from the dark spot area as well as the general body surface. There are as many as 7 types of melanophores termed as A, B, C, AB/AC (all system I deep melanophores) and a, b and c (all system I superficial melanophores). The integument of the fish, however, possesses 3 kinds of chromatophores namely--melanophores, xanthophores and iridophores. The identity of the dark spot as clearly maintained entity independant from the general body surface may be attributed to greater number of system I melanophores, greater melanin content in the system I and system II melanophores, smaller interspaces between system I and system II deep melanophores, greater anastomosing in the superficial melanophores, larger size of system I deep as well as superficial melanophores. The reverse order of the above mentioned factors is responsible for the dull-brownish shade of the general body surface of the fish. The dark spot toward the tail end in the fish, possibly may serve to intimidate or misdirect attack and thus facilitate escape.     

Structure of the integument of a fresh-water teleost,Bagarius bagarius (Ham.) (Sisoridae,pisces)

The skin of Bagarius bagarius (Ham.) is devoid of scales but is rough due to the presence of numerous pentagonal epidermal elevations, which are separated by deep furrows at regular intervals. These elevated pentagonal regions of the epidermis are covered by dead cornified cells in the form of caps. As the old cap goes off a new one is formed by the death of the underlying epidermal cells. The middle layer of the epidermis is mainly composed of well defined polygonal cells. Their cytoplasm is granular in nature and give reactions for protein bound sulphydryl groups. The stratum germinativum is composed of two types of basal cells, the columnar cells and the spherical cells. The flask shaped mucous glands are restricted to the epidermal furrows and secrete either neutral or acidic mucopolysaccharides. Certain large specialysed granular cells are found in the epidermis which are grouped around the taste buds. These specialysed cells may be the photocytes. Two layers of the dermis can be distinguished—the relatively thin stratum laxum and the thick stratum compactum. Dermal papillae mainly support the taste buds. The pigment cells are arranged in two layers in the dermis. The subcutis is composed of loose connective tissues, richly infiltrated with the fat cells, nerves and blood capillaries.     

The immunosuppressive effect of alpha-permethrin on Indian major carp, rohu (Labeo rohita Ham.)

The immunosuppressive effects of bath exposure to a sub lethal concentration of the synthetic pyrethroid alpha-permethrin (3.05 x 10(-4) mg l(-1)) in the Indian Major carp, Labeo rohita was studied after 45 days' exposure. In some groups, the effects of alpha-permethrin on non-specific defences and serum enzymes of carp were investigated after challenge with Aeromonas hydrophila. Several nonspecific immune responses and serum enzymes were reduced after exposure of alpha-permethrin. Bactericidal activity of rohu serum was reduced significantly in pesticide and bacteria treated fish. The Glutamic Oxaloacetate Transaminase (GOT) and Glutamic Pyruvate Transaminase (GPT) activity were increased in immunosuppressed fish. Blood glucose level was elevated significantly and Hb% was reduced significantly in pesticide and bacteria treated fishes as compared to the negative control.     

Succinic dehydrogenase activity of the respiratory muscles of a fresh-water teleost, Bagarius bagarius (Ham.) (Sisoridae, Pisces).

Functional morphology including the origin, insertion, and innervation of the respiratory muscles in relation to buccal pressure pump and opercular suction pumps in a fresh-water bottom dwelling siluroid fish, Bagarius bagarius have been studied. Histochemical studies were made on the succinic dehydrogenase activity of adductor mandibulae, retractor tentaculi, levator operculi, dilatator operculi, adductor operculi, intermandibularis, interhyoideus, hyohyoideus superior and constrictor branchialis. The intensity of reaction reveals the presence of three types of muscle fibres in some of the respiratory muscles. The muscle containing red muscle fibres are mostly innervated by the branches of the VIIth cranial nerve. The retractor tentaculi consists of superficial white muscle fibres and the interior part is dominated by red muscle fibres. The muscles (adductor operculi, levator operculi, dilatator operculi, interhyoideus, hyohyoideus superior) concerned with the opercular suction pumps are of mixed type and consist of white and red muscle fibres, whereas adductor mandibulae and intermandibularis are made up entirely of white muscle fibres. The adductor muscle bundles of the constrictor branchialis, which are responsible for movement of gill filaments, are dominated by the red muscle fibres. The abductor part, however, is made up entirely of white muscle fibres.     

Life history of the river goby Glossogobius callidus (Teleostei: Gobiidae)

The river goby Glossogobius callidus is native to freshwater and estuarine habitats in South Africa. Individuals [21.1–144.4 mm total length (L_T)] were sampled from impoundments in the Sundays River Valley, Eastern Cape, from February 2014 to March 2015. The largest female was 137.2 mm L_T, and the largest male was 144.4 mm L_T. Length-at-50% maturity was 75.2 ± 2.1 mm L_T for males and 76.2 ± 2.0 mm L_T for females. Absolute fecundity was 1028.2 ± 131.7 oocytes per fish, and relative fecundity was 50.1 ± 18.1 oocytes per gram. The spawning season extended from October to December. Fish were aged using sectioned sagittal otoliths. The growth zone periodicity was validated using edge analysis. Longevity was more than 7 years for females and more than 6 years for males. Length-at-age was similar for the two sexes and was best described using the von Bertalanffy growth model as L_t = 74.7(1 − e^{–1.0(t + 0.1)}) mm L_T for the entire population. Using the population age structure, the mortality rate was estimated at 1.3 per year.     

A new goby, Glossogobius minutus (Teleostei: Gobiidae) from the south-west coast of India

A new species of gobiid fish Glossogobius minutus collected from the south-west coast of India is described. The morphological, morphometric and meristic characters were studied with special emphasis on osteology. The various characters are compared with those of G. giuris (Harn.) and G. biocellatus (Val.), the only other species of the genus reported from this region. Glossogobius minutus is a benthic omnivore and shows distinct sexual dimorphism.     

Ovarian and spawning reference,size at first maturity and fecundity of Glossogobius giuris caught along Vietnamese Mekong Delta

This study investigates the ovarian development, spawning patterns, maturity size and fecundity of the goby Glossogobius giuris–a commercial fish in the Vietnamese Mekong Delta–based on the data analysis of 659 individuals. Specimens were caught using trawl nets from four sites representing freshwater (Cai Rang, Can Tho) to salinized regions in the dry season (Long Phu, Soc Trang), and brackish water regions (Hoa Binh, Bac Lieu and Dam Doi, Ca Mau) over the 12 months of 2020. Histological analysis showed that it was a multi-spawner as different stages of oocytes appeared in mature ovaries. The fish could spawn throughout the year, with a peak in April at the freshwater region and in September at salinized and brackish areas as mature ovaries appeared monthly during the studied period and gonadosomatic index displayed the highest value in April and in September, respectively. This goby’s primary egg releasing time tended to be regulated by salinity changes over the four sampling sites. Likewise, size at first maturity of this species could be related to the salinity variation as this value was the longest in freshwater (6.14 ± 0.17) and the shortest in the salinization region (4.82 ± 0.66). Batch fecundity is measured at 5,118–100,003 eggs/female and related to fish length and weight (r² > 0.76). Findings can be useful for the development of fish conservation strategies and artificial reproducing studies.     

Isolation and characterization of immunoglobulin of the Indian major carp, rohu [Labeo rohita (Ham.)

Information on the structure and character of immunoglobulin of fishes is essential in health management. A study was carried out to characterize the serum immunoglobulin (IgM) of the Indian major carp, rohu Labeo rohita (Ham.). Rohu (500g) were immunised with bovine serum albumin (BSA) and the anti-BSA antibody was purified employing BSA-CL agarose affinity column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified Ig in a 3% gel under non-reduced conditions revealed a single protein having a molecular weight of 850kDa. Analysis of the purified serum in 10% SDS-PAGE under reduced conditions revealed that the immunoglobulin contained heavy and light chains with molecular weights of 85 and 23kDa, respectively. A polyclonal mouse anti-rohu IgM was prepared and used in an immunodot test which showed a specific reaction of the crude rohu anti-BSA antiserum and the purified anti-BSA IgM with BSA. Results indicate that the immunoglobulin of L. rohita is tetrameric IgM, similar to that of other fishes.