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Sanjay Kumar - One of the best experts on this subject based on the ideXlab platform.
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an a20 an1 zinc finger domain containing protein gene in tea is differentially expressed during Winter Dormancy and in response to abiotic stress and plant growth regulators
Plant Gene, 2015Co-Authors: Asosii Paul, Sanjay KumarAbstract:Abstract The present manuscript describes cloning and expression characterization of A20/AN1-zinc-finger domain containing protein (CsZfp) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (polyethylene glycol, hydrogen peroxide, and sodium chloride) and plant growth regulators [abscisic acid (ABA), and gibberellic acid (GA3)]. CsZfp encoded a putative protein of 173 amino acids with a calculated molecular weight of 18.44 kDa, an isoelectric point (pI) of 6.50 and grand average of hydropathicity (GRAVY) value of − 0.334. The gene did not have an intron, and belonged to a multi-gene family. During the period of active growth (PAG), CsZfp showed maximum expression in root and fruit as compared to leaf, floral bud and stem. Interaction studies between temperature and plant growth regulators on the expression of CsZfp showed that ABA upregulated CsZfp expression at growth temperature (GT; 25 °C) but had no effect at low temperature (LT; 4 °C). In response to GA3, upregulation was observed at LT but not at GT. Further, the expression was not modulated by LT either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsZfp was upregulated by hydrogen peroxide and sodium chloride, whereas it was non-responsive to polyethylene glycol. The possible role of CsZfp in playing key but differential roles in tea to various abiotic stresses is discussed.
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An A20/AN1-zinc-finger domain containing protein gene in tea is differentially expressed during Winter Dormancy and in response to abiotic stress and plant growth regulators
Plant Gene, 2015Co-Authors: Asosii Paul, Sanjay KumarAbstract:Abstract The present manuscript describes cloning and expression characterization of A20/AN1-zinc-finger domain containing protein (CsZfp) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (polyethylene glycol, hydrogen peroxide, and sodium chloride) and plant growth regulators [abscisic acid (ABA), and gibberellic acid (GA3)]. CsZfp encoded a putative protein of 173 amino acids with a calculated molecular weight of 18.44 kDa, an isoelectric point (pI) of 6.50 and grand average of hydropathicity (GRAVY) value of − 0.334. The gene did not have an intron, and belonged to a multi-gene family. During the period of active growth (PAG), CsZfp showed maximum expression in root and fruit as compared to leaf, floral bud and stem. Interaction studies between temperature and plant growth regulators on the expression of CsZfp showed that ABA upregulated CsZfp expression at growth temperature (GT; 25 °C) but had no effect at low temperature (LT; 4 °C). In response to GA3, upregulation was observed at LT but not at GT. Further, the expression was not modulated by LT either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsZfp was upregulated by hydrogen peroxide and sodium chloride, whereas it was non-responsive to polyethylene glycol. The possible role of CsZfp in playing key but differential roles in tea to various abiotic stresses is discussed.
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alpha tubulin cstua up regulated during Winter Dormancy is a low temperature inducible gene in tea camellia sinensis l o kuntze
Molecular Biology Reports, 2012Co-Authors: Asosii Paul, Paramvir Singh Ahuja, Sanjay KumarAbstract:The present manuscript describes cloning and expression characterization of alpha-tubulin (CsTUA) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (sodium chloride, polyethylene glycol, and hydrogen peroxide) and plant growth regulators [abscisic acid (ABA), gibberellic acid (GA3), indole-3-butyric acid (IBA), and 6-benzylaminopurine (BA)]. CsTUA encoded a putative protein of 449 amino acids with a calculated molecular weight of 49.6 kDa and an isoelectric point (pI) of 5.09. CsTUA shared 76–84 and 90–95% identity at nucleotide and amino acid level, respectively with TUA genes from other plant species. During the period of active growth (PAG), CsTUA showed maximum expression in floral buds as compared to leaf, stem, fruit and root. Though the transcript was not detectable in the younger leaf tissue during the PAG, the expression was induced within 24 h of the low temperature (LT) treatment. The expression was not modulated by the plant growth regulators either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsTUA was up-regulated in response to sodium chloride, polyethylene glycol, and hydrogen peroxide. Data has been discussed on the possible role of CsTUA in imparting tolerance to stresses including to LT so that the tea does not exhibit deciduous nature during Winters.
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responses to Winter Dormancy temperature and plant hormones share gene networks
Functional & Integrative Genomics, 2011Co-Authors: Asosii Paul, Sanjay KumarAbstract:Gene networks modulated in Winter Dormancy (WD) in relation to temperature and hormone responses were analyzed in tea [Camellia sinensis (L.) O. Kuntze]. Analysis of subtracted cDNA libraries prepared using the RNA isolated from the apical bud and the associated two leaves (two and a bud, TAB) of actively growing (AG) and Winter dormant plant showed the downregulation of genes involved in cell cycle/cell division and upregulation of stress-inducible genes including those encoding chaperons during WD. Low temperature (4°C) modulated gene expression in AG cut-shoots in similar fashion as observed in TAB during WD. In tissue harvested during WD, growth temperature (25°C) modulated gene expression in the similar way as observed during the period of active growth (PAG). Abscisic acid (ABA) and gibberellic acid (GA3) modulated expression of selected genes, depending upon if the tissue was harvested during PAG or WD. Tissue preparedness was critical for ABA- and GA3-mediated response, particularly for stress-responsive genes/chaperons. Data identified the common gene networks for Winter Dormancy, temperature, and plant hormone responses.
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tea camellia sinensis clones with shorter periods of Winter Dormancy exhibit lower accumulation of reactive oxygen species
Tree Physiology, 2007Co-Authors: Dhiraj Vyas, Sanjay Kumar, Paramvir Singh AhujaAbstract:Tea (Camellia sinensis (L.) O. Kuntze) is a perennial crop grown throughout the world. During Winter, tea undergoes a Dormancy period when growth of apical buds almost ceases, severely reducing the commercial yield of tea. Low temperatures prevail during the period of Winter Dormancy, which alone or in combination with high solar irradiance have the potential to induce oxidative stress in plants. We studied six tea clones under field conditions to test whether a relationship exists between oxidative stress and Winter Dormancy. Data on the behavior of the enzymatic antioxidative system was collected for all clones during different phases of Winter Dormancy. There was a strong positive correlation among clones between accumulation of reactive oxygen species (ROS) and the length of the Dormancy period. Clones having shorter Dormancy periods exhibited higher induction of antioxidative enzymes. Results suggest that efficient scavenging of ROS is a desirable feature in tea because it leads to lower accumulations of ROS during Winter months and is associated with reduced Winter Dormancy.
Jianyun Ruan - One of the best experts on this subject based on the ideXlab platform.
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Nitrogen absorption by field-grown tea plants (Camellia sinensis) in Winter Dormancy and utilization in spring shoots
Plant and Soil, 2019Co-Authors: Lifeng Ma, Yuanzhi Shi, Jianyun RuanAbstract:AimsThe information of nitrogen uptake by subtropical, ever-green broad-leaf plants at cold temperatures of Winter is very limited. The present field experiment was conducted to investigate whether ^15N is taken up by tea ( Camellia sinensis L.) plants in Winter Dormancy in the absence of active shoot growth and utilization in young spring shoots.MethodsWe applied ^15N-labeled urea to soil at five different times i.e. mid-January, early February, mid-February, and early and mid-March. ^15N abundance was determined in fibrous roots, twigs and mature leaves after 3, 7 and 15 days after application and in young shoots the following spring.Results^15N was taken up by fibrous roots and transported to above-ground tissues within 3 days after application under low Winter temperatures. Earlier application significantly increased nitrogen derived from ^15N-urea (N_dff) and ^15N amount in young spring shoots. N_dff values and ^15N amount in young spring shoots were described well by quadratic or linear regressions against soil growing degree days (GDD, T ≥ 8 °C, depth 20 cm) between ^15N application and harvesting dates (R^2 = 0.58–0.90, p
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Nitrogen absorption by field-grown tea plants ( Camellia sinensis ) in Winter Dormancy and utilization in spring shoots
Plant and Soil, 2019Co-Authors: Lifeng Ma, Jianyun RuanAbstract:The information of nitrogen uptake by subtropical, ever-green broad-leaf plants at cold temperatures of Winter is very limited. The present field experiment was conducted to investigate whether 15N is taken up by tea (Camellia sinensis L.) plants in Winter Dormancy in the absence of active shoot growth and utilization in young spring shoots. We applied 15N-labeled urea to soil at five different times i.e. mid-January, early February, mid-February, and early and mid-March. 15N abundance was determined in fibrous roots, twigs and mature leaves after 3, 7 and 15 days after application and in young shoots the following spring. 15N was taken up by fibrous roots and transported to above-ground tissues within 3 days after application under low Winter temperatures. Earlier application significantly increased nitrogen derived from 15N-urea (Ndff) and 15N amount in young spring shoots. Ndff values and 15N amount in young spring shoots were described well by quadratic or linear regressions against soil growing degree days (GDD, T ≥ 8 °C, depth 20 cm) between 15N application and harvesting dates (R2 = 0.58–0.90, p
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nitrogen absorption by field grown tea plants camellia sinensis in Winter Dormancy and utilization in spring shoots
Plant and Soil, 2019Co-Authors: Jianyun RuanAbstract:The information of nitrogen uptake by subtropical, ever-green broad-leaf plants at cold temperatures of Winter is very limited. The present field experiment was conducted to investigate whether 15N is taken up by tea (Camellia sinensis L.) plants in Winter Dormancy in the absence of active shoot growth and utilization in young spring shoots. We applied 15N-labeled urea to soil at five different times i.e. mid-January, early February, mid-February, and early and mid-March. 15N abundance was determined in fibrous roots, twigs and mature leaves after 3, 7 and 15 days after application and in young shoots the following spring. 15N was taken up by fibrous roots and transported to above-ground tissues within 3 days after application under low Winter temperatures. Earlier application significantly increased nitrogen derived from 15N-urea (Ndff) and 15N amount in young spring shoots. Ndff values and 15N amount in young spring shoots were described well by quadratic or linear regressions against soil growing degree days (GDD, T ≥ 8 °C, depth 20 cm) between 15N application and harvesting dates (R2 = 0.58–0.90, p < 0.001). Nitrogen was absorbed and translocated in dormant tea plants in the absence of active root and shoot growth throughout the late Winter until early spring. Absorbed N was stored and remobilized to support shoot growth the following spring. Soil GDD between N application and harvesting could predict Ndff and 15N amount in young spring shoots.
Asosii Paul - One of the best experts on this subject based on the ideXlab platform.
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an a20 an1 zinc finger domain containing protein gene in tea is differentially expressed during Winter Dormancy and in response to abiotic stress and plant growth regulators
Plant Gene, 2015Co-Authors: Asosii Paul, Sanjay KumarAbstract:Abstract The present manuscript describes cloning and expression characterization of A20/AN1-zinc-finger domain containing protein (CsZfp) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (polyethylene glycol, hydrogen peroxide, and sodium chloride) and plant growth regulators [abscisic acid (ABA), and gibberellic acid (GA3)]. CsZfp encoded a putative protein of 173 amino acids with a calculated molecular weight of 18.44 kDa, an isoelectric point (pI) of 6.50 and grand average of hydropathicity (GRAVY) value of − 0.334. The gene did not have an intron, and belonged to a multi-gene family. During the period of active growth (PAG), CsZfp showed maximum expression in root and fruit as compared to leaf, floral bud and stem. Interaction studies between temperature and plant growth regulators on the expression of CsZfp showed that ABA upregulated CsZfp expression at growth temperature (GT; 25 °C) but had no effect at low temperature (LT; 4 °C). In response to GA3, upregulation was observed at LT but not at GT. Further, the expression was not modulated by LT either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsZfp was upregulated by hydrogen peroxide and sodium chloride, whereas it was non-responsive to polyethylene glycol. The possible role of CsZfp in playing key but differential roles in tea to various abiotic stresses is discussed.
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An A20/AN1-zinc-finger domain containing protein gene in tea is differentially expressed during Winter Dormancy and in response to abiotic stress and plant growth regulators
Plant Gene, 2015Co-Authors: Asosii Paul, Sanjay KumarAbstract:Abstract The present manuscript describes cloning and expression characterization of A20/AN1-zinc-finger domain containing protein (CsZfp) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (polyethylene glycol, hydrogen peroxide, and sodium chloride) and plant growth regulators [abscisic acid (ABA), and gibberellic acid (GA3)]. CsZfp encoded a putative protein of 173 amino acids with a calculated molecular weight of 18.44 kDa, an isoelectric point (pI) of 6.50 and grand average of hydropathicity (GRAVY) value of − 0.334. The gene did not have an intron, and belonged to a multi-gene family. During the period of active growth (PAG), CsZfp showed maximum expression in root and fruit as compared to leaf, floral bud and stem. Interaction studies between temperature and plant growth regulators on the expression of CsZfp showed that ABA upregulated CsZfp expression at growth temperature (GT; 25 °C) but had no effect at low temperature (LT; 4 °C). In response to GA3, upregulation was observed at LT but not at GT. Further, the expression was not modulated by LT either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsZfp was upregulated by hydrogen peroxide and sodium chloride, whereas it was non-responsive to polyethylene glycol. The possible role of CsZfp in playing key but differential roles in tea to various abiotic stresses is discussed.
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alpha tubulin cstua up regulated during Winter Dormancy is a low temperature inducible gene in tea camellia sinensis l o kuntze
Molecular Biology Reports, 2012Co-Authors: Asosii Paul, Paramvir Singh Ahuja, Sanjay KumarAbstract:The present manuscript describes cloning and expression characterization of alpha-tubulin (CsTUA) gene in an evergreen tree tea [Camellia sinensis (L.) O. Kuntze] in response to Winter Dormancy (WD), abiotic stresses (sodium chloride, polyethylene glycol, and hydrogen peroxide) and plant growth regulators [abscisic acid (ABA), gibberellic acid (GA3), indole-3-butyric acid (IBA), and 6-benzylaminopurine (BA)]. CsTUA encoded a putative protein of 449 amino acids with a calculated molecular weight of 49.6 kDa and an isoelectric point (pI) of 5.09. CsTUA shared 76–84 and 90–95% identity at nucleotide and amino acid level, respectively with TUA genes from other plant species. During the period of active growth (PAG), CsTUA showed maximum expression in floral buds as compared to leaf, stem, fruit and root. Though the transcript was not detectable in the younger leaf tissue during the PAG, the expression was induced within 24 h of the low temperature (LT) treatment. The expression was not modulated by the plant growth regulators either in the tissue harvested during PAG or during WD. It was interesting to record that the expression of CsTUA was up-regulated in response to sodium chloride, polyethylene glycol, and hydrogen peroxide. Data has been discussed on the possible role of CsTUA in imparting tolerance to stresses including to LT so that the tea does not exhibit deciduous nature during Winters.
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responses to Winter Dormancy temperature and plant hormones share gene networks
Functional & Integrative Genomics, 2011Co-Authors: Asosii Paul, Sanjay KumarAbstract:Gene networks modulated in Winter Dormancy (WD) in relation to temperature and hormone responses were analyzed in tea [Camellia sinensis (L.) O. Kuntze]. Analysis of subtracted cDNA libraries prepared using the RNA isolated from the apical bud and the associated two leaves (two and a bud, TAB) of actively growing (AG) and Winter dormant plant showed the downregulation of genes involved in cell cycle/cell division and upregulation of stress-inducible genes including those encoding chaperons during WD. Low temperature (4°C) modulated gene expression in AG cut-shoots in similar fashion as observed in TAB during WD. In tissue harvested during WD, growth temperature (25°C) modulated gene expression in the similar way as observed during the period of active growth (PAG). Abscisic acid (ABA) and gibberellic acid (GA3) modulated expression of selected genes, depending upon if the tissue was harvested during PAG or WD. Tissue preparedness was critical for ABA- and GA3-mediated response, particularly for stress-responsive genes/chaperons. Data identified the common gene networks for Winter Dormancy, temperature, and plant hormone responses.
J Rodrigo - One of the best experts on this subject based on the ideXlab platform.
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anther and pollen development in sweet cherry prunus avium l in relation to Winter Dormancy
Protoplasma, 2019Co-Authors: Erica Fadon, M Herrero, J RodrigoAbstract:Anther and pollen development is a highly conserved process in angiosperms, but while pollen formation in annual plants occurs in a few days, in temperate woody perennials, it requires several months. How anther and pollen development is framed in terms of seasonality plays a clear part in reproductive success. In this study, seasonal anther and pollen development is characterized in two sweet cherry cultivars over 2 years, paying special attention to the period of Dormancy and unveiling the role of starch in this process. We evaluated starch content from the autumn until bud burst with the help of an image analysis system fitted to a light microscope. Microscope observations allowed the temporal relationship of pollen development to the phenological stages of flower and bud development to be determined. In both cultivars and years, anther and pollen development followed the same pattern. Development was halted by Dormancy, when the anthers showed no morphological changes until several weeks after chilling fulfillment, until the milder temperatures reactivated development. After Dormancy, starch was accumulated in the connective tissue until tracheary element differentiation. Quantification of starch in the connective tissue of anthers revealed its importance in supporting pollen meiosis and subsequent anther growth.
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unveiling Winter Dormancy through empirical experiments
Environmental and Experimental Botany, 2017Co-Authors: E Fadon, J RodrigoAbstract:Abstract Temperate woody perennials enter into a dormant status during Winter in order to survive low temperatures. However, Dormancy is not just a survival strategy, since cold Winter temperatures are required for proper flowering. Global warming is having an impact on the phenology of woody perennials; warmer temperatures during Dormancy may lead to an erratic reproductive behaviour due to the lack of chilling accumulated during Winter. Although the relevance of Dormancy for the adaptation of temperate woody perennials is well known, the biological processes behind Dormancy remain unclear. In this work, we review how shoot and seedling experiments have contributed to the current knowledge on Dormancy in woody perennials from the early discovery of the role of cold temperatures for adequate flowering to the latest knowledge on Dormancy physiology and genetics. The information available has been organised in seven sections: (i) Climate change and Winter Dormancy in woody perennials; (ii) Discovering the importance of cold and the establishment of Dormancy bases; (iii) Experiments to estimate the Dormancy period; (iv) Exploring the physiology of Dormancy; (v) Looking for biological markers for the Dormancy status through histochemical techniques; (vi) Molecular biology of bud Dormancy and (vii) Conclusions and perspectives.
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stamen development and Winter Dormancy in apricot prunus armeniaca
Annals of Botany, 2011Co-Authors: C Julian, J Rodrigo, M HerreroAbstract:Background and Aims In temperate woody perennials, flower bud development is halted during the Winter, when the buds enter Dormancy. This dormant period is a prerequisite for adequate flowering, is genetically regulated, and plays a clear role in possibly adapting species and cultivars to climatic areas. However, information on the biological events underpinning Dormancy is lacking. Stamen development, with clear differentiated stages, appears as a good framework to put Dormancy in a developmental context. Here, stamen developmental changes are characterized in apricot (Prunus armeniaca) and are related to Dormancy.
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part of a special issue on sexual plant reproduction stamen development and Winter Dormancy in apricot prunus armeniaca
2011Co-Authors: C Julian, J Rodrigo, M HerreroAbstract:† Background and Aims In temperate woody perennials, flower bud development is halted during the Winter, when the buds enter Dormancy. This dormant period is a prerequisite for adequate flowering, is genetically regulated, and plays a clear role in possibly adapting species and cultivars to climatic areas. However, information on the biological events underpinning Dormancy is lacking. Stamen development, with clear differentiated stages, appears as a good framework to put Dormancy in a developmental context. Here, stamen developmental changes are characterized in apricot (Prunus armeniaca) and are related to Dormancy. † Methods Stamen development was characterized cytochemically from the end of August to March, over 4 years. Developmental changes were related to Dormancy, using the existing empirical information on chilling requirements. † Key Results Stamen development continued during the autumn, and the flower buds entered Dormancy with a fully developed sporogenous tissue. Although no anatomical changes were observed during Dormancy, breaking of Dormancy occurred following a clear sequence of events. Starch accumulated in particular places, pre-empting further development in those areas. Vascular bundles developed and pollen mother cells underwent meiosis followed by microspore development. † Conclusions Dormancy appears to mark a boundary between the development of the sporogenous tissue and the occurrence of meiosis for further microspore development. Breaking of Dormancy occurs following a clear sequence of events, providing a developmental context in which to study Winter Dormancy and to evaluate differences in chilling requirements among genotypes.
Amitabh Krishna - One of the best experts on this subject based on the ideXlab platform.
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melatonin modulates glucose homeostasis during Winter Dormancy in a vespertilionid bat scotophilus heathi
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2010Co-Authors: Raj Kamal Srivastava, Amitabh KrishnaAbstract:Abstract The role for melatonin in glucose homeostasis and insulin resistance is not very clear and has recently been an active area of investigation. The present study investigated the role of melatonin in seasonal accumulation of adipose tissue in Scotophilus heathi , with particular reference to its role in glucose homeostasis and development of insulin resistance. The circulating melatonin levels correlated positively ( p S. heathi . The bats showed high circulating blood glucose levels and impaired glucose tolerance during the period of fat deposition suggesting insulin resistance condition which improves after Winter when most of the fat has been utilized as a metabolic fuel. The high circulating melatonin levels during the period of maximum body fat at the beginning of Winter prepare the bats for Winter Dormancy by modulating the glucose homeostasis through affecting blood glucose levels, muscle and liver glycogen stores, insulin receptor and glucose transporter 4 (GLUT 4) expression. This is also confirmed by in vivo study in which melatonin injection improves the glucose tolerance, increases muscle insulin receptor and GLUT 4 expression, and enhances glucose clearance from the blood. The results of present study further showed that the effect of melatonin injection on the blood glucose levels is determined by the metabolic state of the bats and may protect from decrease in blood glucose level during extreme starvation, however, melatonin when injected during fed state increases glucose clearance from the blood. In summary, the present study suggested that melatonin interferes with the glucose homeostasis through modulating intracellular glucose transport and may protect bats from hypoglycemia during Winter Dormancy.
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adiposity associated rise in leptin impairs ovarian activity during Winter Dormancy in vespertilionid bat scotophilus heathi
Reproduction, 2007Co-Authors: Raj Kamal Srivastava, Amitabh KrishnaAbstract:The aim of the study was to evaluate the seasonal variation in serum leptin levels in a natural population of the female bat, Scotophilus heathi and their relationship to the changes in the body mass, serum insulin level, and ovarian activity. Circulating leptin level varied significantly over the season and correlated positively with the changes in body mass, and circulating insulin and androstenedione (A4) levels. Circulating leptin concentrations showed two peaks; one coincides with the maximum fat accumulation prior to Winter Dormancy, whereas the second shorter peak coincides with late pregnancy. The in vivo study in S. heathi showed that the increased circulating leptin level during Winter Dormancy coincides with the decreased expression of ovarian steroidogenic acute regulatory (StAR) protein, and low circulating estradiol (E 2 ) level. At the same time, increased circulating leptin level coincides with increased expression of ovarian insulin receptor and high circulating A4 level. The low circulating leptin level during preovulatory period coincides with the increase in StAR protein but decrease in insulin receptor protein. The in vitro study confirmed the in vivo observations of inhibitory effect of leptin on LH induced StAR expression and E 2 production, whereas the stimulatory effect of leptin (high dose) on LH induced expression of insulin receptor protein and A4 production. However, pharmacological dose of leptin produced inhibitory effect on the expression of insulin receptor protein. The results of the present study thus suggest that high circulating leptin level during Winter Dormancy promotes adiposity and impairs ovarian activity by suppressing StAR-mediated E 2 production as well as by enhancing insulin receptor-mediated A4 synthesis thereby contributing anovulatory condition of delayed ovulation in S. heathi.
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Histochemical localization of enzymes and lipids in the ovary of a vespertilionid bat, Scotophilus heathi, during the reproductive cycle
Brazilian Journal of Biology, 2005Co-Authors: U. P. Singh, Amitabh Krishna, Timothy D. Smith, Kunwar P. BhatnagarAbstract:The present study describes seasonal changes in D5 3b hydroxysteroid dehydrogenase (3b-HSD), glusose-6 phosphates dehydrogenase (G-6-PD), and lipids in the ovary of a vespertilionid bat, Scotophilus heathi. Total lipids and 3b-HSD activity are restricted to thecal and interstitial cells of the ovary. The total lipids, 3b-HSD, and G-6-PD significantly increase during recrudescence, and remain high during Winter Dormancy and breeding as compared to the other reproductive phases. High incidence of lipids and enzyme activity in interstitial cells during the breeding period and at the time of ovulation clearly suggests that these cells are actively involved in steroidogenesis. A decline in enzymes and lipid activity during Winter Dormancy, which correlates with the declining levels of steroidogenesis, might be the factors responsible for prolonged survival of the Graafian follicle in the ovary of S. heathi.
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Seasonal changes in thyroid activity in the female sheath-tailed bat, Taphozous longimanus (Chiroptera: Emballonuridae)
Acta Biologica Hungarica, 2002Co-Authors: U. P. Singh, Amitabh Krishna, Kunwar P. BhatnagarAbstract:The present study was designed to investigate changes in thyroid activity during the reproductive cycle in Taphozous longimanus. Thyroid gland showed marked seasonal variation in weight and secretory activity. It was inactive in quiescence and early to mid-Winter Dormancy and active during recrudescence and breeding period during late Winter Dormancy. The serum 3,5,3′-triiodothyronine (T3) and thyroxine (T4) concentrations showed significant variation and closely coincided with thyroid activity. The T3 and T4 concentrations were higher in recrudescence, late Winter Dormancy and minimum in quiescence and initial stages of first pregnancy. The body weight (r = 0.56), ovary weight (r = 0.73), and thyroid weight (r = 0.70) showed correlation with each other and with T3 and T4 concentrations. The correlation between body weight, thyroid weight and T3 and T4 concentrations in non-pregnant bats was higher when compared with pregnant bats. The T3 and T4 levels remained low during the initial stages of development in first pregnancy when compared with the initial stages of second pregnancy. The scant food supply and low levels of T3 and T4 and low temperature during initial stages of first pregnancy might be responsible for differential rate of fetal development in two successive pregnancies in T. longimanus.
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Changes in circulating insulin and corticosterone concentrations during different reproductive phases and their relationships to body weight and androstenedione concentration of male Scotophilus heathi.
Journal of Experimental Zoology, 1998Co-Authors: Amitabh Krishna, Kavita Singh, Jayashree Doval, D. ChandaAbstract:The aim of the present study was to determine the serum levels of insulin and corticosterone during different reproductive stages in a natural population of the male bat, Scotophilus heathi and their relationship to body weight and androstenedione level. Changes in body weight were marked by weight gain before Winter Dormancy and weight loss during Winter Dormancy. Circulating insulin level varied significantly over the season and correlated positively with changes in body weight and androstenedione level. Circulating corticosterone level also varied significantly over the season but correlated negatively with changes in body weight and androstenedione level. High corticosterone level during August coincided with a period of increased feeding activity in this species. The results suggest that insulin may act as an anabolic agent to promote fat deposition and corticosterone exerts a predominantly fat-mobilizing influence. A high insulin level prior to Winter Dormancy may be an important factor responsible for inducing high androstenedione concentration shown in Scotophilus heathi.
