20 results on '"Rajanathan R"'
Search Results
2. Understanding Human–Canid Conflict and Coexistence: Socioeconomic Correlates Underlying Local Attitude and Support Toward the Endangered Dhole (Cuon alpinus) in Bhutan
- Author
-
Phuntsho Thinley, Rajanathan Rajaratnam, Lam Norbu, Lungten Dorji, Jigme Tenzin, Chhimi Namgyal, Choney Yangzom, Tashi Wangchuk, Sonam Wangdi, Tshering Dendup, Sonam Tashi, and Cheten Wangmo
- Subjects
attitude toward wildlife ,dhole conservation ,endangered canid ,human-canid conflict ,livestock depredation ,socioeconomic correlates ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Understanding human–canid conflict and coexistence must focus on documenting human–canid interactions and identifying the underlying drivers of reciprocal human attitude which enables appropriate strategies to minimize conflict and forge coexistence. The dhole (Cuon alpinus), Asia's most widely distributed wild canid, is highly threatened by human persecution and anthropogenic activities. Despite its “endangered” status, its ecological role as an apex predator, negative interactions with humans, and dhole-specific attitude studies are limited, thus hindering the development of a comprehensive dhole-conservation strategy. Here, we investigate the influence of socioeconomic factors of age, gender, income, residency inside/outside a protected area (PA), and other variables (cultural beliefs, livestock loss, and quantity of livestock loss) on the attitudes of local people and support for dhole conservation in the Himalayan Kingdom of Bhutan. We conducted a semi-structured questionnaire survey of 1,444 households located within the PA and non-PA from four representative regions in the country. Using R programming, we ran Pearson's chi-square test of independence to test the overall difference in the attitude and support for dhole conservation, followed by recursive partitioning through a conditional inference regression tree to identify its significant covariates with the highest explanatory power. Majority (79.1%) of respondents (χ2 = 488.6; df = 1; p < 0.001) disliked the dhole over those who liked it. More than half (57.7%) (χ2 = 412.7; df = 2; p < 0.001) opposed dhole conservation over those who either supported or remained neutral. Experience of livestock loss to dholes was the primary ( p < 0.001) factor influencing the negative attitude and opposition to dhole conservation, despite an acknowledgment of the ecological role of the dhole in controlling agricultural crop predators. Our study, which is the first-ever survey in Bhutan, solely focused on investigating human attitudes and perceptions toward the dhole, indicating that livestock loss to dholes transcends all positive attitudes to the species and drives a predominant dislike and opposition to its conservation. To improve the attitude and support toward the dhole and to foster dhole–human coexistence, livestock predation by dholes needs alleviation by improving the existing animal husbandry, in conjunction with promoting conservation awareness on this species.
- Published
- 2021
- Full Text
- View/download PDF
3. Conserving an Endangered Canid: Assessing Distribution, Habitat Protection, and Connectivity for the Dhole (Cuon alpinus) in Bhutan
- Author
-
Phuntsho Thinley, Rajanathan Rajaratnam, Jan F. Kamler, and Cheten Wangmo
- Subjects
Bhutan ,biological corridors ,dhole conservation ,dhole distribution ,endangered canid ,protected areas ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Most canids face population declines and range contractions worldwide. Although the dhole (Cuon alpinus) is widely distributed across 10 countries in South and Southeast Asia, limited studies exist on this species. Despite its globally “Endangered” status and ecological role as an apex predator, assessments on its distribution are limited to a few landscapes and countries. This explains the lack of a dhole-specific species conservation plan in most range countries, including Bhutan where no current population estimate exists. The species has also recovered from a country-wide poisoning campaign in the 1970s and 80s. In this study, we determine the dhole's distribution pattern and assess the protection and connectivity of dhole habitat in Bhutan. We anticipated dholes to be extant within their habitat well-represented in protected areas (PAs) and biological corridors (BCs). We used 721 georeferenced dhole occurrence records and eight environmental variables in MaxEnt software to model potential dhole distribution and habitat suitability. The model output was overlaid on the spatial layers of PAs and BCs to assess habitat protection and connectivity. As anticipated, we found the dhole widely distributed in all districts, PAs, and BCs in Bhutan. Dholes were recorded at the highest elevation range limit of 4,980 m above sea level, which overlapped with the “Vulnerable” snow leopard (Panthera uncia). Our model identified 72% (27,634 km2) of the country as suitable areas for dholes, of which, 31% (11,899 km2) was highly suitable and 41% (15,735 km2) was moderately suitable. Contrary to our expectation, PAs and BCs encompassed only 29% (8,046 km2) and 12% (3,185 km2) of suitable areas for dholes, respectively. A vast majority of the areas we deemed suitable for dholes currently remain unprotected, thus making dholes more vulnerable to human persecution and local extermination. We recommend adjusting PA boundaries to fully encompass suitable dhole habitat, and also advocate improved livestock husbandry to reduce dhole related livestock predation and minimize conflict, thereby ensuring its long-term survival in Bhutan.
- Published
- 2021
- Full Text
- View/download PDF
4. Assessing the adequacy of a protected area network in conserving a wide‐ranging apex predator: The case for tiger (Panthera tigris) conservation in Bhutan
- Author
-
Phuntsho Thinley, Rajanathan Rajaratnam, Stephen J. Morreale, and James P. Lassoie
- Subjects
Apex predator ,Bhutan ,biological corridor ,endangered species ,tiger ,protected area ,Ecology ,QH540-549.5 ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Abstract Protected area networks (PAN) are essential for conserving wide‐ranging apex predators but their adequacy in species protection has rarely been assessed. Here, we assess the adequacy of Bhutan's PAN in conserving and providing connectivity to the endangered tiger (Panthera tigris). We determine the current extent of tiger habitat, predict new suitable habitat, identify potential corridors, and empirically estimate the range of tiger numbers that Bhutan can spatially support. We use two spatial models with different approaches to ascertain current tiger distribution and predict new suitable tiger areas: (a) an expert model based on tiger ecology and (b) an observation model from observed tiger distribution. The expert model identified more suitable tiger areas (32,887 km2) over the observation model (29,962 km2), with the PAN encompassing 46% and 45% of predicted suitable areas, respectively. Vast suitable tiger habitat remains unprotected. Based on our estimates of total suitable habitats, Bhutan can spatially support 138–151 tigers compared to the current estimate of 103, thereby precluding a doubling in tiger numbers. To ensure adequate protection of tigers in Bhutan, we recommend readjusting and/or expanding existing PAN boundaries, including the designation of new corridors, protecting habitats, and conserving prey populations.
- Published
- 2021
- Full Text
- View/download PDF
5. Current distribution and conservation status of Bhutan Takin Budorcas whitei Lydekker, 1907 (Artiodactyla: Bovidae)
- Author
-
Tiger Sangay, Rajanathan Rajaratnam, and Karl Vernes
- Subjects
Bhutan ,Budorcas ,conservation ,habitat ,migration ,Takin. ,Ecology ,QH540-549.5 ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The Bhutan Takin Budorcas whitei Lydekker, 1907 is endemic to Bhutan and it is categorized as Vulnerable by the IUCN Red List of Threatened Species. While the other Takin species have been studied in China (Golden Takin B. bedfordi; Sichuan Takin B. tibetana) and India (Mishmi Takin B. taxicolor), only one study has focused on the Bhutan Takin. In this paper, we report the current distribution and conservation status of the Bhutan Takin using the information gathered through field surveys, interviews and unpublished reports. Bhutan Takin are seasonal migrants, occurring between 1500–5550 m, preferring areas in close proximity to river valleys and geothermal outlets (hot springs). Takin avoid areas that are disturbed by road construction and power transmission lines, and where they have to compete for forage with domestic livestock. Takin conservation in Bhutan requires: (1) a commitment to reduce disturbances from domestic livestock through better herding and animal husbandry practices, (2) environmentally friendly road construction, inclusive of wildlife corridors, (3) establishment of satellite offices and regularizing anti-poaching patrol systems, (4) development of education programs to enlist support for Takin conservation, and (5) encouragement of more research on the ecology and management needs of the species.
- Published
- 2016
- Full Text
- View/download PDF
6. Using GPS Technology to Understand Spatial and Temporal Activity of Kangaroos in a Peri-Urban Environment
- Author
-
Timothy Henderson, Karl Vernes, Gerhard Körtner, and Rajanathan Rajaratnam
- Subjects
kangaroo ,GPS telemetry ,movement ecology ,activity pattern ,peri-urban ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
The increasing kangaroo occurrence in expanding peri-urban areas can be problematic when kangaroos become aggressive towards people and present a collision risk to motor vehicles. An improved understanding on kangaroo spatial and temporal activity patterns in the peri-urban environment is essential to manage kangaroo–human conflict. In this study, we used GPS telemetry to determine activity patterns of male Eastern Grey Kangaroos (Macropus giganteus) in a peri-urban community on the north-coast of New South Wales, Australia. Two types of GPS devices were employed; collars and cheaper alternative glue-on units. Kangaroos moved on average 2.39 km a day, with an average movement rate of 1.89 m/min, which was greatest at dawn. The GPS glue-on devices had short deployment lengths of one to 12 days. Despite limitations in attachment time, the glue-on devices were viable in obtaining daily spatial and temporal activity data. Our results aid towards alleviating conflict with kangaroos by providing new insights into kangaroo movements and activity within a peri-urban environment and introduces a potential cheap GPS alternative for obtaining this data relative to more expensive collars.
- Published
- 2018
- Full Text
- View/download PDF
7. Habitat correlates of the red panda in the temperate forests of Bhutan.
- Author
-
Sangay Dorji, Karl Vernes, and Rajanathan Rajaratnam
- Subjects
Medicine ,Science - Abstract
Anthropogenic activities and associated global climate change are threatening the biodiversity in the Himalayas against a backdrop of poor knowledge of the region's threatened species. The red panda (Ailurus fulgens) is a threatened mammal confined to the eastern Himalayas, and because of Bhutan's central location in the distributional range of red pandas, its forests are integral to the long-term viability of wild populations. Detailed habitat requirements of the red panda are largely speculative, and there is virtually no ecological information available on this species in Bhutan. Between 2007 and 2009, we established 615 presence/absence plots in a systematic sampling of resident habitat types within Jigme Dorji and Thrumshingla National Parks, Bhutan, to investigate broad and fine-scale red panda habitat associations. Additional locality records of red pandas were obtained from interviewing 664 park residents. Red pandas were generally confined to cool broadleaf and conifer forests from 2,110-4,389 m above sea level (asl), with the majority of records between 2,400-3,700 m asl on south and east-facing slopes. At a finer scale, multivariate analysis revealed that red pandas were strongly associated with old growth Bhutan Fir (Abies densa) forest dominated by a dense cover of Yushania and Arundanaria bamboo with a high density of fallen logs and tree stumps at ground level; a high density of trees, dead snags, and rhododendron shrubs in the mid-storey; and locations that were close to water. Because Bhutan's temperate forests that encompass prime red panda habitat are also integral to human subsistence and socio-economic development, there exists an inadvertent conflict between the needs of people and red pandas. As such, careful sustainable management of Bhutan's temperate forests is necessary if a balance is to be met between the socioeconomic needs of people and the conservation goals for red pandas.
- Published
- 2011
- Full Text
- View/download PDF
8. Spinal cord blood flow elevation with systemic vasopressor noradrenaline is partly mediated by vasodilation of spinal arteries due to reduced expression of alpha adrenoreceptors.
- Author
-
Entezari S, Thygesen MM, Staehr C, Melnikova E, Skov M, Rajanathan R, Rasmussen M, Rasmussen MM, and Matchkov VV
- Abstract
Background Context: . Elevation of mean arterial blood pressure (MAP) has been proposed to raise spinal cord blood flow (SCBF) after traumatic spinal cord injury (TSCI). Current clinical guidelines for cervical TSCI suggest maintaining MAP 85-90 mmHg for 5-7 days using vasopressors, e.g., noradrenaline. However, it remains unknown whether these interventions that promote an increased systemic MAP result in improved perfusion in the spinal cord. The local effect of vasopressors on the spinal cord arteries also remains unknown., Purpose: The aim of this study was to investigate whether the increased systemic MAP results in increased SCBF, and secondly, to examine the mechanism behind noradrenaline (NA) action in spinal cord arteries., Study Design: . An experimental animal study., Methods: . The study included nine 38-42 kg landrace pigs. In six pigs, MAP was gradually elevated using NA and continuous SCBF was recorded by laser doppler flowmetry. Spinal cord samples from these six pigs were excised for isolation of spinal cord arteries that were used for ex-vivo vascular function assessment in isometric myograph. Segments of mesentery from another three pigs were used to dissect mesenteric small arteries that were also studied in myograph, as control peripheral arteries. Other spinal cord and mesenteric arterial segments from the same biopsies were dissected and snap-frozen for the following expression analysis. Adrenoceptor's expression in arteries of all included animals was assessed with quantitative PCR., Results: . The controlled mixed model found that SCBF was lower at MAP below 50 mmHg and that SCBF increased significantly in the MAP range of 50-100 mmHg (p = 0.02). Further increase of MAP did not significantly affect SCBF (at MAP range of 100-150 mmHg, p = 0.15; at 150-200 mmHg, p = 0.51). However, SCBF significantly increased over the study time-course (at 80 min, p = 0.002; at 100 min, p < 0.001), which was dependent on the experimental duration being a confounder of increased exposure to large doses of NA. Isolated spinal arteries did not contract to NA ex-vivo and even showed a tendency for vasorelaxation. This relaxation was abolished by β-adrenoceptor inhibitor, propranolol. In contrast, mesenteric arteries were contracted by NA and propranolol potentiated this contraction. Mesenteric arteries showed a higher expression of α1A adrenoceptors than spinal arteries, while no significant difference was found in other adrenoceptor isoforms., Conclusions: . We found SCBF reduced at MAP below 50 mmHg and that the SCBF increased significantly in MAP range between 50-100 mmHg. Elevating MAP above 100 mmHg was not associated with a further increase in SCBF. We also showed that NA increases SCBF in-vivo and relaxes spinal arteries ex-vivo. This effect was associated with a low arterial expression of α adrenoceptors over β adrenoceptors in the spinal cord., Clinical Significance: . These findings challenge the assumption that SCBF is solely dictated by MAP within autoregulatory limits, emphasizing the necessity of considering noradrenaline-induced vasorelaxation in the spinal arteries of TSCI patients., Competing Interests: Declaration of competing interest The authors have no competing interests to disclose., (Copyright © 2024. Published by Elsevier Inc.)
- Published
- 2024
- Full Text
- View/download PDF
9. Hypercontractile Cardiac Phenotype in Mice with Migraine-Associated Mutation in the Na + ,K + -ATPase α 2 -Isoform.
- Author
-
Rajanathan R, Riera CVI, Pedersen TM, Staehr C, Bouzinova EV, Nyengaard JR, Thomsen MB, Bøtker HE, and Matchkov VV
- Subjects
- Mice, Animals, Sodium-Potassium-Exchanging ATPase genetics, Sodium-Potassium-Exchanging ATPase metabolism, Ouabain pharmacology, Protein Isoforms metabolism, Mutation genetics, Phenotype, Atrial Fibrillation, Migraine Disorders
- Abstract
Two α-isoforms of the Na
+ ,K+ -ATPase (α1 and α2 ) are expressed in the cardiovascular system, and it is unclear which isoform is the preferential regulator of contractility. Mice heterozygous for the familial hemiplegic migraine type 2 (FHM2) associated mutation in the α2 -isoform (G301R; α2 +/G301R mice) have decreased expression of cardiac α2 -isoform but elevated expression of the α1 -isoform. We aimed to investigate the contribution of the α2 -isoform function to the cardiac phenotype of α2 +/G301R hearts. We hypothesized that α2 +/G301R hearts exhibit greater contractility due to reduced expression of cardiac α2 -isoform. Variables for contractility and relaxation of isolated hearts were assessed in the Langendorff system without and in the presence of ouabain (1 µM). Atrial pacing was performed to investigate rate-dependent changes. The α2 +/G301R hearts displayed greater contractility than WT hearts during sinus rhythm, which was rate-dependent. The inotropic effect of ouabain was more augmented in α2 +/G301R hearts than in WT hearts during sinus rhythm and atrial pacing. In conclusion, cardiac contractility was greater in α2 +/G301R hearts than in WT hearts under resting conditions. The inotropic effect of ouabain was rate-independent and enhanced in α2 +/G301R hearts, which was associated with increased systolic work.- Published
- 2023
- Full Text
- View/download PDF
10. Augmented Ouabain-Induced Vascular Response Reduces Cardiac Efficiency in Mice with Migraine-Associated Mutation in the Na + , K + -ATPase α 2 -Isoform.
- Author
-
Rajanathan R, Pedersen TM, Guldbrandsen HO, Olesen LF, Thomsen MB, Bøtker HE, and Matchkov VV
- Abstract
Heterozygous mice (α
2 +/G301R mice) for the migraine-associated mutation (G301R) in the Na+ ,K+ -ATPase α2 -isoform have decreased expression of cardiovascular α2 -isoform. The α2 +/G301R mice exhibit a pro-contractile vascular phenotype associated with decreased left ventricular ejection fraction. However, the integrated functional cardiovascular consequences of this phenotype remain to be addressed in vivo. We hypothesized that the vascular response to α2 -isoform-specific inhibition of the Na+ ,K+ -ATPase by ouabain is augmented in α2 +/G301R mice leading to reduced cardiac efficiency. Thus, we aimed to assess the functional contribution of the α2 -isoform to in vivo cardiovascular function of wild-type (WT) and α2 +/G301R mice. Blood pressure, stroke volume, heart rate, total peripheral resistance, arterial dP/dt, and systolic time intervals were assessed in anesthetized WT and α2 +/G301R mice. To address rate-dependent cardiac changes, cardiovascular variables were compared before and after intraperitoneal injection of ouabain (1.5 mg/kg) or vehicle during atrial pacing. The α2 +/G301R mice showed an enhanced ouabain-induced increase in total peripheral resistance associated with reduced efficiency of systolic development compared to WT. When the hearts were paced, ouabain reduced stroke volume in α2 +/G301R mice. In conclusion, the ouabain-induced vascular response was augmented in α2 +/G301R mice with consequent suppression of cardiac function.- Published
- 2023
- Full Text
- View/download PDF
11. Phenylephrine-Induced Cardiovascular Changes in the Anesthetized Mouse: An Integrated Assessment of in vivo Hemodynamics Under Conditions of Controlled Heart Rate.
- Author
-
Rajanathan R, Pedersen TM, Thomsen MB, Botker HE, and Matchkov VV
- Abstract
Objective: Investigating the cardiovascular system is challenging due to its complex regulation by humoral and neuronal factors. Despite this complexity, many existing research methods are limited to the assessment of a few parameters leading to an incomplete characterization of cardiovascular function. Thus, we aim to establish a murine in vivo model for integrated assessment of the cardiovascular system under conditions of controlled heart rate. Utilizing this model, we assessed blood pressure, cardiac output, stroke volume, total peripheral resistance, and electrocardiogram (ECG)., Hypothesis: We hypothesize that (i) our in vivo model can be utilized to investigate cardiac and vascular responses to pharmacological intervention with the α
1 -agonist phenylephrine, and (ii) we can study cardiovascular function during artificial pacing of the heart, modulating cardiac function without a direct vascular effect., Methods: We included 12 mice that were randomly assigned to either vehicle or phenylephrine intervention through intraperitoneal administration. Mice were anesthetized with isoflurane and intubated endotracheally for mechanical ventilation. We measured blood pressure via a solid-state catheter in the aortic arch, blood flow via a probe on the ascending aorta, and ECG from needle electrodes on the extremities. Right atrium was electrically paced at a frequency ranging from 10 to 11.3 Hz before and after either vehicle or phenylephrine administration., Results: Phenylephrine significantly increased blood pressure, stroke volume, and total peripheral resistance compared to the vehicle group. Moreover, heart rate was significantly decreased following phenylephrine administration. Pacing significantly decreased stroke volume and cardiac output both prior to and after drug administration. However, phenylephrine-induced changes in blood pressure and total peripheral resistance were maintained with increasing pacing frequencies compared to the vehicle group. Total peripheral resistance was not significantly altered with increasing pacing frequencies suggesting that the effect of phenylephrine is primarily of vascular origin., Conclusion: In conclusion, this in vivo murine model is capable of distinguishing between changes in peripheral vascular and cardiac functions. This study underlines the primary effect of phenylephrine on vascular function with secondary changes to cardiac function. Hence, this in vivo model is useful for the integrated assessment of the cardiovascular system., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rajanathan, Pedersen, Thomsen, Botker and Matchkov.)- Published
- 2022
- Full Text
- View/download PDF
12. Abnormal neurovascular coupling as a cause of excess cerebral vasodilation in familial migraine.
- Author
-
Staehr C, Rajanathan R, Postnov DD, Hangaard L, Bouzinova EV, Lykke-Hartmann K, Bach FW, Sandow SL, Aalkjaer C, and Matchkov VV
- Subjects
- Animals, Disease Models, Animal, Endothelial Cells metabolism, Female, Hyperemia enzymology, Hyperemia physiopathology, Male, Mice, Transgenic, Middle Cerebral Artery enzymology, Migraine with Aura enzymology, Migraine with Aura genetics, Mutation, Potassium Channels, Inwardly Rectifying metabolism, Sodium-Potassium-Exchanging ATPase genetics, Cerebrovascular Circulation, Middle Cerebral Artery physiopathology, Migraine with Aura physiopathology, Neurovascular Coupling, Sodium-Potassium-Exchanging ATPase metabolism, Vasodilation
- Abstract
Aims: Acute migraine attack in familial hemiplegic migraine type 2 (FHM2) patients is characterized by sequential hypo- and hyperperfusion. FHM2 is associated with mutations in the Na, K-ATPase α2 isoform. Heterozygous mice bearing one of these mutations (α2+/G301R mice) were shown to have elevated cerebrovascular tone and, thus, hypoperfusion that might lead to elevated concentrations of local metabolites. We hypothesize that these α2+/G301R mice also have increased cerebrovascular hyperaemic responses to these local metabolites leading to hyperperfusion in the affected part of the brain., Methods and Results: Neurovascular coupling was compared in α2+/G301R and matching wild-type (WT) mice using Laser Speckle Contrast Imaging. In brain slices, parenchymal arteriole diameter and intracellular calcium changes in neuronal tissue, astrocytic endfeet, and smooth muscle cells in response to neuronal excitation were assessed. Wall tension and smooth muscle membrane potential were measured in isolated middle cerebral arteries. Quantitative polymerase chain reaction, western blot, and immunohistochemistry were used to assess the molecular background underlying the functional changes. Whisker stimulation induced larger increase in blood perfusion, i.e. hyperaemic response, of the somatosensory cortex of α2+/G301R than WT mice. Neuronal excitation was associated with larger parenchymal arteriole dilation in brain slices from α2+/G301R than WT mice. These hyperaemic responses in vivo and ex vivo were inhibited by BaCl2, suggesting involvement of inward-rectifying K+ channels (Kir). Relaxation to elevated bath K+ was larger in arteries from α2+/G301R compared to WT mice. This difference was endothelium-dependent. Endothelial Kir2.1 channel expression was higher in arteries from α2+/G301R mice. No sex difference in functional responses and Kir2.1 expression was found., Conclusion: This study suggests that an abnormally high cerebrovascular hyperaemic response in α2+/G301R mice is a result of increased endothelial Kir2.1 channel expression. This may be initiated by vasospasm-induced accumulation of local metabolites and underlie the hyperperfusion seen in FHM2 patients during migraine attack., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)
- Published
- 2020
- Full Text
- View/download PDF
13. Conservation threats to the endangered golden langur (Trachypithecus geei, Khajuria 1956) in Bhutan.
- Author
-
Thinley P, Norbu T, Rajaratnam R, Vernes K, Dhendup P, Tenzin J, Choki K, Wangchuk S, Wangchuk T, Wangdi S, Chhetri DB, Powrel RB, Dorji K, Rinchen K, and Dorji N
- Subjects
- Accidents, Traffic, Agriculture, Animals, Bhutan, Construction Industry, Dogs, Electric Injuries veterinary, Hybridization, Genetic, Risk Assessment, Conservation of Natural Resources methods, Ecosystem, Endangered Species, Presbytini
- Abstract
Threat assessment is critical to species conservation and management planning, because prior identification and assessment of key threats to conservation planning can assist in developing appropriate interventions or strategies. Comprehensive threat assessments are currently lacking for many threatened primates. In this paper, we classify and rank all direct threats to the endangered golden langur (Trachypithecus geei) in Bhutan in order to provide a practical guide to future conservation of the species. Information on threats was based on interviews with local people, discussion with field forestry staff, and social media interaction. We classified threats to golden langur habitats and populations, and ranked them using Miradi™, an analytical software for the adaptive management of conservation projects. We identified five habitat threats: (1) hydropower development, (2) road development, (3) housing development, (4) resource extraction, and (5) agricultural expansion. We also identified seven population threats: (1) electrocution, (2) road kill, (3) road injury, (4) dog kill, (5) retaliatory killing, (6) illegal pet keeping, and (7) hybridization with capped langurs. We rated the overall threat to golden langurs in Bhutan as 'medium'. Hydropower, road, and housing development constituted 'high' impact, while agricultural expansion, resource extraction, electrocution, and road kill had 'medium' impact; the remaining threats had 'low' impact. To immediately mitigate threats to golden langurs, we recommend: (a) installing speed limit signage and speed breakers with strict enforcement of speed limits; (b) installing insulated electric cables and fencing around power transformers; and (c) reducing and restraining domestic dog populations.
- Published
- 2020
- Full Text
- View/download PDF
14. Population abundance and distribution of the endangered golden langur (Trachypithecus geei, Khajuria 1956) in Bhutan.
- Author
-
Thinley P, Norbu T, Rajaratnam R, Vernes K, Wangchuk K, Choki K, Tenzin J, Tenzin S, Kinley, Dorji S, Wangchuk T, Cheda K, and Gempa
- Subjects
- Animals, Bhutan, Ecosystem, Female, Male, Population Density, Animal Distribution, Endangered Species, Presbytini physiology
- Abstract
Reliable population estimates are lacking for many South Asian primate species, including the golden langur (Trachypithecus geei), which is endangered and restricted to Bhutan and northeast India. Although well studied in India, few studies exist on this species in Bhutan. In November 2017, we undertook a nationwide survey of golden langurs in Bhutan using double observers along trail-based transects in 17 blocks within its habitat, and modeled its distribution using MaxEnt. A total of 2439 golden langurs in 222 groups were collectively encountered by 17 teams of double observers, from which, an overall population of 2516 ± SE 363 individuals and 236 ± SE 9 groups were estimated. Group sizes varied from 2 to 35 individuals with a mean of 11 ± SD 0.38 individuals. A total of 468 adult males (19%), 924 adult females (38%), 649 juveniles (27%), and 398 infants (16%) were counted. Adult male-to-female sex ratio was 1:1.97 and adult female-to-infant ratio was 1:0.43. We determined 2848 km
2 of suitable area for golden langurs in Bhutan and estimated a density of 0.88 individuals/km2 . Our population estimate of golden langurs in Bhutan is much lower than the current IUCN estimate of 4000 individuals for Bhutan, necessitating a reassessment of its current conservation status due to threats from road kills, electrocution, and development activities like road construction, hydropower, and electrical transmission lines. We further recommend our refined double-observer survey method to reliably estimate primate populations in rugged terrain.- Published
- 2019
- Full Text
- View/download PDF
15. Smooth muscle Ca 2+ sensitization causes hypercontractility of middle cerebral arteries in mice bearing the familial hemiplegic migraine type 2 associated mutation.
- Author
-
Staehr C, Hangaard L, Bouzinova EV, Kim S, Rajanathan R, Boegh Jessen P, Luque N, Xie Z, Lykke-Hartmann K, Sandow SL, Aalkjaer C, and Matchkov VV
- Subjects
- Animals, Calcium metabolism, Mice, Middle Cerebral Artery metabolism, Migraine with Aura genetics, Muscle, Smooth, Vascular metabolism, Point Mutation, Cerebrovascular Circulation genetics, Migraine with Aura metabolism, Muscle Contraction genetics, Sodium-Potassium-Exchanging ATPase genetics, Vasoconstriction genetics
- Abstract
Familial hemiplegic migraine type 2 (FHM2) is associated with inherited point-mutations in the Na,K-ATPase α2 isoform, including G301R mutation. We hypothesized that this mutation affects specific aspects of vascular function, and thus compared cerebral and systemic arteries from heterozygote mice bearing the G301R mutation (Atp1a2
+/-G301R ) with wild type (WT). Middle cerebral (MCA) and mesenteric small artery (MSA) function was compared in an isometric myograph. Cerebral blood flow was assessed with Laser speckle analysis. Intracellular Ca2+ and membrane potential were measured simultaneously. Protein expression was semi-quantified by immunohistochemistry. Protein phosphorylation was analysed by Western blot. MSA from Atp1a2+/-G301R and WT showed similar contractile responses. The Atp1a2+/-G301R MCA constricted stronger to U46619, endothelin and potassium compared to WT. This was associated with an increased depolarization, although the Ca2+ change was smaller than in WT. The enhanced constriction of Atp1a2+/-G301R MCA was associated with increased cSrc activation, stronger sensitization to [Ca2+ ]i and increased MYPT1 phosphorylation. These differences were abolished by cSrc inhibition. Atp1a2+/-G301R mice had reduced resting blood flow through MCA in comparison with WT mice . FHM2-associated mutation leads to elevated contractility of MCA due to sensitization of the contractile machinery to Ca2+ , which is mediated via Na,K-ATPase/Src-kinase/MYPT1 signalling.- Published
- 2019
- Full Text
- View/download PDF
16. Understanding primate-human interaction: Socioeconomic correlates of local awareness and attitude toward the endangered golden langur Trachypithecus geei (Khajuria, 1956) in Bhutan.
- Author
-
Thinley P, Rajaratnam R, Tighe M, Vernes K, Norbu T, Dorji R, and Tenzin S
- Subjects
- Adult, Animals, Bhutan, Crop Production, Culture, Female, Humans, Male, Middle Aged, Rural Population, Socioeconomic Factors, Surveys and Questionnaires, Endangered Species, Presbytini, Public Opinion
- Abstract
Despite the golden langur's (Trachypithecus geei) endangered and totally protected status, local awareness and attitude toward this species is poorly understood. We investigated local awareness and attitude in Bhutan by interviewing 1,143 households in the districts of Dagana, Sarpang, Trongsa, Tsirang, and Zhemgang, and analyzing data through a conditional inference tree analysis. Most respondents were not aware of the golden langur's nationally protected (53%; n = 604) and globally endangered status (64%; n = 730), but their location of residence (inside/outside a protected area; p < .001) and education level (p < .001) significantly influenced awareness. The majority of respondents (87%; n = 999) liked the golden langur but the attitude was significantly influenced primarily by whether or not they experienced crop damage by golden langurs (p < .001), and subsequently by location of residence (p < .001), local belief (p < .01), gender (p < .05), and personal encounter with a golden langur (p < .001). Socioeconomic variables like age, education level, and annual income did not influence attitude. We recommend environmental education and awareness campaigns outside protected areas, and intensifying existing programs inside protected areas to forge harmonious human-golden langur coexistence., (© 2019 Wiley Periodicals, Inc.)
- Published
- 2019
- Full Text
- View/download PDF
17. Involvement of the Na + ,K + -ATPase isoforms in control of cerebral perfusion.
- Author
-
Staehr C, Rajanathan R, and Matchkov VV
- Subjects
- Animals, Astrocytes drug effects, Astrocytes enzymology, Cerebrovascular Circulation drug effects, Enzyme Inhibitors pharmacology, Humans, Isoenzymes chemistry, Isoenzymes physiology, Muscle, Smooth, Vascular drug effects, Neurovascular Coupling drug effects, Ouabain pharmacology, Sodium-Potassium-Exchanging ATPase antagonists & inhibitors, Sodium-Potassium-Exchanging ATPase chemistry, Cerebrovascular Circulation physiology, Muscle, Smooth, Vascular enzymology, Neurovascular Coupling physiology, Sodium-Potassium-Exchanging ATPase physiology
- Abstract
New Findings: What is the topic of this review? In this review, we consider the role of the Na
+ ,K+ -ATPase in cerebrovascular function and how it might be changed in familial hemiplegic migraine type 2 (FHM2). The primary focus is involvement of the Na+ ,K+ -ATPase isoforms in regulation of cerebrovascular tone. What advances does it highlight? In this review, we discuss three overall distinct mechanisms whereby the Na+ ,K+ -ATPase might be capable of regulating cerebrovascular tone. Furthermore, we discuss how changes in the Na+ ,K+ -ATPase in cerebral arteries might affect brain perfusion and thereby be involved in the pathology of FHM2., Abstract: Familial hemiplegic migraine type 2 (FHM2) has been characterized by biphasic changes in cerebral blood flow during a migraine attack, with initial hypoperfusion followed by abnormal hyperperfusion of the affected hemisphere. We suggested that FHM2-associated loss-of-function mutation(s) in the Na+ ,K+ -ATPase α2 isoform might be responsible for these biphasic changes in several ways. We found that reduced expression of the α2 isoform leads to sensitization of the contractile machinery to [Ca2+ ]i via Src kinase-dependent signal transduction. This change in sensitivity might be the underlying mechanism for both abnormally potentiated vasoconstriction and exaggerated vasorelaxation. Moreover, the functional significance of the Na+ ,K+ -ATPase α2 isoform in astrocytes provides for the possibility of elevated extracellular potassium signalling from astrocytic endfeet to the vascular wall in neurovascular coupling., (© 2019 The Authors. Experimental Physiology © 2019 The Physiological Society.)- Published
- 2019
- Full Text
- View/download PDF
18. Identifying conservation priorities for threatened Eastern Himalayan mammals.
- Author
-
Dorji S, Rajaratnam R, Falconi L, Williams SE, Sinha P, and Vernes K
- Subjects
- Animals, Endangered Species, Mammals, Spatial Analysis, Biodiversity, Conservation of Natural Resources
- Abstract
To augment mammal conservation in the Eastern Himalayan region, we assessed the resident 255 terrestrial mammal species and identified the 50 most threatened species based on conservation status, endemism, range size, and evolutionary distinctiveness. By using the spatial analysis package letsR and the complementarity core-area method in the conservation planning software Zonation, we assessed the current efficacy of their protection and identified priority conservation areas by comparing protected areas (PAs), land cover, and global ecoregion 2017 maps at a 100 × 100 m spatial scale. The 50 species that were most threatened, geographically restricted, and evolutionarily distinct faced a greater extinction risk than globally nonthreatened and wide-ranging species and species with several close relatives. Small, medium-sized, and data-deficient species faced extinction from inadequate protection in PAs relative to wide-ranging charismatic species. There was a mismatch between current PA distribution and priority areas for conservation of the 50 most endangered species. To protect these species, the skewed regional PA distribution would require expansion. Where possible, new PAs and transboundary reserves in the 35 priority areas we identified should be established. There are adequate remaining natural areas in which to expand current Eastern Himalayan PAs. Consolidation and expansion of PAs in the EH requires strengthening national and regional transboundary collaboration, formulating comprehensive regional land-use plans, diversifying conservation funding, and enhancing information sharing through a consolidated regional database., (© 2018 Society for Conservation Biology.)
- Published
- 2018
- Full Text
- View/download PDF
19. Using GPS Technology to Understand Spatial and Temporal Activity of Kangaroos in a Peri-Urban Environment.
- Author
-
Henderson T, Vernes K, Körtner G, and Rajaratnam R
- Abstract
The increasing kangaroo occurrence in expanding peri-urban areas can be problematic when kangaroos become aggressive towards people and present a collision risk to motor vehicles. An improved understanding on kangaroo spatial and temporal activity patterns in the peri-urban environment is essential to manage kangaroo⁻human conflict. In this study, we used GPS telemetry to determine activity patterns of male Eastern Grey Kangaroos ( Macropus giganteus ) in a peri-urban community on the north-coast of New South Wales, Australia. Two types of GPS devices were employed; collars and cheaper alternative glue-on units. Kangaroos moved on average 2.39 km a day, with an average movement rate of 1.89 m/min, which was greatest at dawn. The GPS glue-on devices had short deployment lengths of one to 12 days. Despite limitations in attachment time, the glue-on devices were viable in obtaining daily spatial and temporal activity data. Our results aid towards alleviating conflict with kangaroos by providing new insights into kangaroo movements and activity within a peri-urban environment and introduces a potential cheap GPS alternative for obtaining this data relative to more expensive collars.
- Published
- 2018
- Full Text
- View/download PDF
20. Habitat correlates of the red panda in the temperate forests of Bhutan.
- Author
-
Dorji S, Vernes K, and Rajaratnam R
- Subjects
- Animals, Bhutan, Ecology, Multivariate Analysis, Ailuridae, Ecosystem, Trees
- Abstract
Anthropogenic activities and associated global climate change are threatening the biodiversity in the Himalayas against a backdrop of poor knowledge of the region's threatened species. The red panda (Ailurus fulgens) is a threatened mammal confined to the eastern Himalayas, and because of Bhutan's central location in the distributional range of red pandas, its forests are integral to the long-term viability of wild populations. Detailed habitat requirements of the red panda are largely speculative, and there is virtually no ecological information available on this species in Bhutan. Between 2007 and 2009, we established 615 presence/absence plots in a systematic sampling of resident habitat types within Jigme Dorji and Thrumshingla National Parks, Bhutan, to investigate broad and fine-scale red panda habitat associations. Additional locality records of red pandas were obtained from interviewing 664 park residents. Red pandas were generally confined to cool broadleaf and conifer forests from 2,110-4,389 m above sea level (asl), with the majority of records between 2,400-3,700 m asl on south and east-facing slopes. At a finer scale, multivariate analysis revealed that red pandas were strongly associated with old growth Bhutan Fir (Abies densa) forest dominated by a dense cover of Yushania and Arundanaria bamboo with a high density of fallen logs and tree stumps at ground level; a high density of trees, dead snags, and rhododendron shrubs in the mid-storey; and locations that were close to water. Because Bhutan's temperate forests that encompass prime red panda habitat are also integral to human subsistence and socio-economic development, there exists an inadvertent conflict between the needs of people and red pandas. As such, careful sustainable management of Bhutan's temperate forests is necessary if a balance is to be met between the socioeconomic needs of people and the conservation goals for red pandas.
- Published
- 2011
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.