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Departure from naturalized to invasive stage:a disturbanceinduced mechanism and associated interacting factors

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Journal of Plant Ecology 2010年第4期3卷 231-242页

作者： amit chakraborty Bai-Lian Li Ecological Complexity and Modeling Laboratory Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCA 92521-0124USA Center for Conservation Biology University of CaliforniaRiversideCA 92521-0334USA CAU-UCR International Center for Ecology and Sustainability University of CaliforniaRiversideCA 92521USA

Aims Within a habitat of multiple plant species,increased resource availabilities and altered species abundances following disturbances create opportunities for exotic species to successfully establish and subsequently naturalize into its non-native *** post-disturbance changes in abiotic and biotic environments may also promote a naturalized exotic species(or invading species)to become invasive through rapid colonization of the habitat sites by reducing the extent and size of resident plant *** combining species life history traits with that of the disturbance-induced changes in habitat characteristics,we aimed to determine those interacting factors and associated mechanism allowing an exotic invasion to start *** We used a modified version of the classic competition–colonization(CC)model which was formulated first by Hastings(1980)and studied later by Tilman(1994)to explain spatial coexistence of multiple *** this model framework,recruitment-limited spatial competition has explicitly been linked with interspecific resource competition without altering the basic assumptions and structure of the original CC *** findings The model results showed that at a constant rate of resource supply,invading species can stably coexist with native species via trade-offs between species competitive ability and colonizing *** the other hand,the model predicted that with a fluctuating resource condition,invading species can successfully invade a habitat following continuous reductions in the size and extent of native *** or not invading species holds competitive superiority over the native species for limiting resource,we showed that there exists a range of variation in available resource that allows an exotic invasion to start off in post-disturbance *** associated disturbance-induced mechanism promoting invading species to become invasive has been *** states that occurrences of disturbances suc

关键词： invasion naturalized species spatial competition propagule supply resource variation

Contribution of biodiversity to ecosystem functioning:a non-equilibrium thermodynamic perspective

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Journal of Arid Land 2011年第1期3卷 71-74页

作者： amit chakraborty B Larry LI Ecological Complexity and Modeling Laboratory Department of Botany and Plant SciencesUniversity of California XIEG-UCR International Center for Arid Land Ecology University of California

Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regulation of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy （a measure of irre- versibility） degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.

关键词： ecosystem self-organization non-equilibrium thermodynamics functional diversity phenotypic diversity

Spatial organization of multiple plant species in arid ecosystems:linking patterns and processes

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Journal of Arid Land 2010年第1期2卷 9-13页

作者： amit chakraborty B.Larry LI Ecological Complexity and Modeling Laboratory Department of Botany and Plant SciencesUniversity of California Center for Conservation Biology University of California XIEG-UCR International Center for Arid Land Ecology University of California

Spatial organization of multiple plant species that appears as a non-random distribution of vegetative patches is one of the mostly observed spatial patterns in arid ecosystems. Yet understanding of ecological processes allowing this spatial pattern to emerge through interspecific interactions is still lacking. With a proposed conceptual model involving interspecific trade-offs between species competitive ability and colonization ability, we have argued that within patch abundance dynamics regulated by the mechanisms of competition are strongly influenced by the between patches colonization dynamics that are maintained via this trade-offs and it holds a positive, intraspecific occupancy-abundance relationship, in which increased patch occupancy increases species density within inhabiting patches. In a constant environment, while local abundance dynamics approach toward a stable equilibrium point, a fixed spatial arrangement of species can be retained through this coupled dynamics. However, in fluctuating environments where existence of such stable equilibriums is highly uncertain, it may involve continuous transitions from one community state to another as species re-organized themselves over space through the rapid changes in local species abundances. While some of the inhabiting patches are destroyed exogenously or endogenously, or species responses to increasing environmental fluctuations vary increasingly with time, discontinuous transitions into an abrupt, irreversible state of the community dynamics may occur, as with this effect the inherent positive relationship between occupancy and abundance of species is no longer maintained.

关键词： spatial organization competition-colonization tradeoffs spatial coexistence occupancy-abundance relationship

A facile synthesis of a novel optoelectric material: a nanocomposite of SWCNT/ZnO nanostructures embedded in sulfonated polyaniline

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International Journal of Smart and Nano Materials 2014年第3期5卷 180-193页

作者： Rajesh K.Agrawalla Rima Paul Pratap K.Sahoo amit K.chakraborty Apurba Krishna Mitra Physics NIT DurgapurDurgapur 713209India b Physics NISERBhubaneswarIndia

Functionalized single-walled carbon nanotubes(f-SWCNTs)hybridized with freshly prepared zinc oxide(ZnO)nanocrystals have been found to be good luminescent material with tuned emission properties.A three-phase nanocomposite of sulfonated polyaniline embedded with such SWCNT/ZnO nanostructures has been prepared by a simple solution mixing chemical process and characterized by using high-resolution transmission electron microscopy,X-ray diffractometry,Raman spectroscopy,Fourier transform infrared spectroscopy,and thermogravimetric *** study of UVvisible absorption and photoluminescence spectroscopies reveal that the ternary polymer nanocomposite is a luminescent material with enhanced emission *** an increase in DC conductivity indicates that the nanocomposite is also a good conductive material,satisfying Mott’s variable range hopping model for a two-dimensional *** a three-phase nanocomposite may find extensive application in dye-sensitized solar cells,sensors,and supercapacitors.

关键词： SPANI SWCNT/ZnO hybrid polymer nanocomposite

EFFECT OF ACUPUNCTURE ON PLASMA GLUCOSE LEVEL IN HUMAN VOLUNTEERS

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World Journal of Acupuncture-Moxibustion 2006年第4期16卷 24-27页

作者： amit Kumar chakraborty Mrigendranath Gantait Biswapati Mukherjee Dr. B. K. Basu Memorial Research and Training Institute of Acupuncture Kolkata West Bengal India S.N. Pradhan Centre for Neurosciences University of Calcutta Kolkata West Bengal India

Objective To observe the changes of plasma glucose level （PGL） in human volunteers after acupuncture. Methods Seventy-seven human volunteers were taken up from the acupuncture clinic. All of them were non-diabetic subjects. Electroacupuncture at acupoints Zhongwan （中脘 CV 12） and Guanyuan （关元 CV 4） was given for 20 minutes. Venous blood was collected before acupuncture and 10 minutes after completion of acupuncture. All cases were at four hours abstinence from food before doing acupuncture. Results Plasma glucose level varied 5 mg% or more in 62 cases （80.51%） and only those were considered for computation. PGL increased in cases who had generally plasma glucose level below 90 mg% before acupuncture; and PGL decreased in cases who had plasma glucose 90 mg% or above. In 10 control cases there was no variation of the considerable level of 5 mg% in any case. Conclusion Bi-directional variation of PGL after acupuncture indicates that acupuncture can be used to maintain optimum PGL through endogenous mechanism, suggesting that it is applicable in controlling hyperglycemia in diabetes rnellitus patients.

关键词： Acupuncture efficacy Plasma glucose Bi-directional effect of acupuncture Diabetes

EFFICACY OF ACUPUNCTURE THERAPY ON A, B AND O BLOOD GROUPS ──Relationship between A, B, O blood groups and the acupuncture therapy

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World Journal of Acupuncture-Moxibustion 2005年第2期15卷 18-20页

作者： amit Kr. chakraborty Mrigendranath Gantait Biswapati Mukherjee Dr. B. K. Basu Memorial Research & Training Institute of Acupuncture 188/87 Prince Anwar Shah Road Kolkata 700 045 West Bengal IndiaDr. B. K. Basu Memorial Research & Training Institute of Acupuncture 188/87 Prince Anwar Shah Road Kolkata 700 045 West Bengal India S. N. Pradhan Centre for Neurosciences University of Calcutta Kolkata 700 020 West Bengal India.

Efficacy of acupuncture therapy varies in patients with similar ailments. The present study was undertaken to search for a marker for better efficacy of acupuncture therapy. The study was made in 224 patients including osteoarthritis 141 (62.94 %), polyarthritis 23 (10.26 %), Bursitis & synovitis 15 (6.69 %) and others 45 (20.08 %). ABO blood groups were tested for each patient. It appears that patients belonging to group AB and B responded well to acupuncture therapy in proportionately more number. Good result was achieved in 47.82 % cases in group AB and 46.04 % cases in group B, whereas patients of group A and O showed good result in 27.65 % and 26.15 % cases respectively. Apparently it may be concluded that patients of AB & B blood groups would respond comparatively well to acupuncture therapy.

关键词： Acupuncture efficacy ABO blood groups Acupuncture therapy

Elevated Vascular Endothelial Growth Factor Level in Association with Mean Platelet Volume Are Emerging Risk Factors for Vascular Complications in T2DM Patients

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Health 2019年第11期11卷 1542-1553页

作者： Priyanka Biswas amit Kr. chakraborty Anumoy Mukherjee Baidyanath Pal Debasish Maji Madhusnata De Department of Genetics Vivekananda Institute of Medical Sciences Ramakrishna Mission Seva Pratishthan Kolkata India Department of Pathology Murshidabad Medical College and Hospital Berhampore India Biological Anthropological Unit Indian Statistical Institute Kolkata India Department of Endocrinology Vivekananda Institute of Medical Sciences Ramakrishna Mission SevaPratishthan Kolkata India

Increasing evidence in both experimental and clinical studies suggests oxidative stress (OS) plays a major role in the pathogenesis of type 2 diabetes mellitus and its complications. In a physiological condition, appropriate levels of ROS, generated either in restricted amounts or transient fashion, are required to promote physiological angiogenesis and homeostatic maintenance of healthy vasculature. Uncontrolled continuous ROS production will ultimately contribute to pathology and cause tissue damage. One of the most important proangiogenic factors is vascular endothelial growth factor (VEGF) which plays a key role in diabetic endothelial dysfunction, which ultimately leads to pathogenesis of vascular complications. As VEGF is released by activated platelets, hence platelet activation could be the source of VEGF in plasma samples. Increased platelet activity is emphasized to play a role in the development of vascular complications in T2DM patients and platelet volume, a marker of the platelet function and activation, is measured as mean platelet volume (MPV). Therefore, we aimed to investigate the association between plasma VEGF levels and MPV levels that may lead to vascular complications. A case-control study of one hundred patients with T2DM (n = 100) and thirty control subjects (n = 30) were screened from different areas of West Bengal. All procedures were done with the informed consent of participants. Elevated VEGF level was found in T2DM patients (526.8 ± 34.3 pg/ml) compared to healthy controls (317.9 ± 12.9 pg/ml) which was statistically significant. T2DM patients had higher MPV (12.5 ± 0.2 fl) compared to controls (11.4 ± 0.2 fl). Thus the present study showed a significant association between VEGF level in plasma and MPV indicating the severity of vascular complications. Hence, in conclusion, it suggested that VEGF levels along with MPV are a reliable biomarker for evaluating the development and progression of vascular complications.

关键词： Oxidative Stress Vascular Endothelial Growth Factor Mean Platelet Volume Vascular Complications

Understanding activity of butyrate at a cellular level

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Neural Regeneration Research 2025年第8期20卷 2323-2324页

作者： Prapti chakraborty Angela S.Laird Macquarie University Motor Neuron Disease Research Centre Macquarie Medical SchoolFaculty of MedicineHealth and Human SciencesMacquarie UniversitySydneyAustralia

Butyrate is a short-chain fatty acid of four carbons in length that is a by-product produced by the microbial fermentation of dietary fiber and undigested carbohydrates within the *** the years,butyrate has attracted ... 详细信息

关键词： carbons butyrate fiber

Review of the potential of mesenchymal stem cells for the treatment of infectious diseases

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World Journal of Stem Cells 2021年第6期13卷 568-593页

作者： amit Sharma Anuja chakraborty Bithiah Grace Jaganathan Stem Cell and Cancer Biology Group Department of Biosciences and BioengineeringIndian Institute of Technology GuwahatiGuwahati 781039India

The therapeutic value of mesenchymal stem cells (MSCs) for the treatment of infectious diseases and the repair of disease-induced tissue damage has been explored extensively. MSCs inhibit inflammation, reduce pathogen load and tissue damage encountered during infectious diseases through the secretion of antimicrobial factors for pathogen clearance and they phagocytose certain bacteria themselves. MSCs dampen tissue damage during infection by downregulating thelevels of pro-inflammatory cytokines, and inhibiting the excessive recruitment ofneutrophils and proliferation of T cells at the site of injury. MSCs aid in theregeneration of damaged tissue by differentiating into the damaged cell types orby releasing paracrine factors that direct tissue regeneration, differentiation, andwound healing. In this review, we discuss in detail the various mechanisms bywhich MSCs help combat pathogens, tissue damage associated with infectiousdiseases, and challenges in utilizing MSCs for therapy.

关键词： Infectious diseases Mesenchymal stem cells Antimicrobial effect Immunomodulation Tissue repair COVID-19