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Amul Sakharkar Praful Singru Nishikant Subhedar 《Fish physiology and biochemistry》2005,31(2-3):163-166
We studied GnRH immunoreactivity in the pineal gland of the Indian major carp Cirrhinus mrigala during different phases of reproductive cycle. In the resting phase (December–January), GnRH immunoreactive (-ir) fibers
were organized as paired fascicles above the posterior commissure that ascend in the stalk and distribute widely in the pineal
gland. The GnRH-ir fiber density significantly declined (P<0.001) during the preparatory phase (February–April) and the fibers disappeared thereafter. While no GnRH fibers were seen
during the prespawning (May–June) and spawning (July–August), isolated GnRH-ir fibers reappeared in the postspawning phase.
Since no GnRH cell bodies were detected in the pineal, these GnRH-ir fibers seem to be of central origin. The results reveal
a distinct reciprocal relationship between the GnRH immunoreactivity in the pineal and the status of the ovarian maturity;
the fibers appeared in the pineal only during the period of ovarian quiescence. While the functional significance of these
cyclic changes in GnRH is yet to be determined, we suggest that the decapeptide may serve as a transmitter of central origin
that modulates the activity of the pineal gland. 相似文献
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Praful S. Singru Amul J. Sakharkar Minakshi Mazumdar Nishikant Subhedar 《Fish physiology and biochemistry》2007,33(4):297-309
Ultrastructural localization of neuronal nitric oxide synthase (nNOS) in olfactory receptor neurons (ORNs) and immunohistochemical
detection of the enzyme in forebrain, pituitary, and pineal were undertaken in the teleost Oreochromis mossambicus. Application of post-embedding immunoelectron microscopy revealed nNOS-labeled gold particles on the cilia, microvilli, mitochondria,
and Golgi complex of the ORNs. Gold particles were also seen adhered to microtubules in the axons that extend to the olfactory
nerve layer in the olfactory bulb. With light microscopy, nNOS-immunoreactive neurons were seen in preoptic area, nucleus
entopeduncularis, and parvocellular, and magnocellular subdivisions of nucleus preopticus (NPO). Numerous cerebrospinal fluid-contacting
cells lining the wall of the third ventricle at the level of the NPO showed intense immunoreactivity. Intense to moderate
immunoreactivity was observed in the neurons of suprachiasmatic nucleus, nucleus lateralis tuberis pars lateralis, and nucleus
recessus lateralis. While several immunoreactive fibers were detected in medial olfactory tract, suprachiasmatic area, and
hypothalamo-hypophyseal tract, a few were seen throughout the telencephalon, in the optic chiasma, tuberal area, and inferior
lobes. In the pituitary, nNOS-containing fibers were seen in the neurohypophysis, rostral pars distalis, proximal pars distalis,
and pars intermedia. While intense immunoreactivity was noticed in some cells in the pineal, immunoreactive fibers were detected
in the pineal stalk as well as parenchyma. We suggest that nitric oxide may play a role in processing olfactory and photic
information, circadian rhythms, and neuroendocrine regulation in tilapia. 相似文献
3.
Nishikant Subhedar Archana Gaikwad K. C. Biju Subhash Saha 《Fish physiology and biochemistry》2005,31(2-3):167-172
Significance of NPY in the regulation of GnRH–LH axis was evaluated. Considerable NPY immunoreactivity was seen in the components
like olfactory system, basal telencephalon, preoptic and tuberal areas, and the pituitary gland that serve as neuroanatomical
substrates for processing reproductive information. Close anatomical association as well as colocalizations of NPY and GnRH
were seen in the olfactory receptor neurons, olfactory nerve fibers and their terminals in the glomeruli, ganglion cells of
nervus terminalis, medial olfactory tracts, fibers in the ventral telencephalon and pituitary. In the pituitary, NPY fibers
seem to innervate the GnRH as well as LH cells. Intracranial administration of NPY resulted in significant increase in the
GnRH immunoreactivity in all the components of the olfactory system. In the pituitary, NPY augmented the population of GnRH
fibers and LH cells. HPLC analysis showed that salmon GnRH content in the olfactory organ, bulb, preoptic area+telencephalon
and pituitary was also significantly increased following NPY treatment. NPY may play a role in positive regulation of GnRH
throughout the neuraxis and also up-regulate the LH cells in the pituitary. 相似文献
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In light of the traditional claim of Cyperus rotundus in the treatment of diabetes, investigations were carried out to evaluate its effect on alloxan induced hyperglycemia in rats. Oral daily administration of 500 mg/kg of the extract (once a day for seven consecutive days) significantly lowered the blood glucose levels. This antihyperglycemic activity can be attributed to its antioxidant activity as it showed the strong DPPH radical scavenging action in vitro. 相似文献
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Minakshi Mazumdar Praful Singru Amul Sakharkar Makrand Deshmukh Nishikant Subhedar 《Fish physiology and biochemistry》2005,31(2-3):173-176
Glucagon-like peptide-1-immunoreactivity (GLP-ir) was seen in several olfactory receptor neurons in the olfactory epithelium
and in the olfactory nerve fascicles that extend caudally to the bulb and innervate the glomerular layer. Thick GLP-ir fascicles
were seen in the medial olfactory tracts (MOT); these probably represent the extrabulbar olfactory projections. GLP-ir fibers
in the MOT penetrate into the telencephalon, swing dorsocaudally into the area ventralis telencephali/pars supracommissuralis
(Vs) just above the anterior commissure. The immunoreactive fascicles continue caudally in the dorsal hypothalamus and are
traceable as far as the lateral recesses. Scattered GLP-ir fibers were seen in the ventral telencephalon and preoptic area.
While several immunoreactive cells were seen in the pars intermedia of the pituitary gland, few were encountered in the rostral
pars distalis and proximal pars distalis. Role for the peptide in the processing of olfactory information and in the regulation
of pituitary gland may be suggested. 相似文献
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Nishikant Gupta Varun Tiwari Mark Everard Melissa Savage Syed Ainul Hussain Michael A. Chadwick Jeyaraj Antony Johnson Asghar Nawab Vinod K. Belwal 《水产资源保护:海洋与淡水生态系统》2020,30(3):601-610
- The Eurasian otter (Lutra lutra), smooth‐coated otter (Lutrogale perspicillata), and Asian small‐clawed otter (Aonyx cinereus) have all been reported previously from the Indian state of Uttarakhand. However, little information is available about their current distribution in a mountainous region that is subject to increasing human‐induced stressors (such as hydropower plants, pollution, sand and boulder mining, destructive fishing techniques, poaching).
- Owing to important roles played by these otters in structuring riverine food webs (particularly taking account of their roles as top carnivores), it is critical that they receive suitable protection in the face of projected temperature rise, change in precipitation patterns, and associated river flows in this Himalayan biodiversity hotspot. This study assesses otter distribution in four rivers of Uttarakhand as a basis for informing future conservation actions.
- Field surveys were conducted (October 2018–January 2019) in reaches of the Kosi, Ramganga, Khoh, and Song rivers, supported by semi‐structured interviews (N = 379) conducted with members of local communities to collect qualitative data on views and perceptions of otter species. In addition, community‐based otter awareness camps were organized for local youths (N = 105), adults (N = 115), and schoolchildren (N = 256 covering 10 schools).
- Habitat suitability maps were created using remote‐sensing data, survey findings, and a geographic information system to provide information about priority reaches of river to be targeted for future conservation efforts.
- This study provides critical interdisciplinary baseline information to guide decision‐makers towards developing a targeted, otter‐specific conservation programme for this important Himalayan biodiversity hotspot.
- The otter conservation education programmes conducted during this study resulted in a proposal to set up a community‐based conservation initiative to monitor and report otter sightings from the area, potentially representing a way forward for achieving simultaneous otter conservation and associated ecosystem benefits for local communities.
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Nishikant Gupta Mark Everard Prakash Nautiyal Ishaan Kochhar Kuppusamy Sivakumar Jeyaraj Antony Johnson Atul Borgohain 《水产资源保护:海洋与淡水生态系统》2020,30(2):394-401
- Mahseer (Tor) fish species are critical components of locally adapted freshwater food webs across the Indian Himalayan biodiversity hotspot; however, multiple human stressors compounded by climate change have significantly depleted their populations over recent decades.
- Mahseer species are now considered locally vulnerable or endangered in many regions. Hydropower projects in particular have fragmented populations, impairing genetic exchange, obstructing migratory paths, and changing the structure and functioning of riverine habitats, especially of formerly fast‐flowing rivers.
- Worryingly, a literature survey and group discussions reveal that the increasing spread of non‐native fish species further compounds threats to mahseer and overall freshwater ecology. A better understanding of the current distribution, habitat requirement, and dispersal of non‐native fish is therefore essential to manage the growing threats to mahseer in the Indian Himalayan region.
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