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आयतन 8, मुद्दा 4 (2020)

सार विस्तारित

Biodiversity - 2015: Single-cell analysis reveals gene-expression heterogeneity in microbial syntrophic dual culture

Weiwen Zhang

Microbial syntrophic metabolism has been well accepted because the heart of how methanogenic and other anaerobic microbial communities function. Dissimilatory sulfate-reducing prokaryotes (SRB) are a various group of anaerobic bacteria that are widespread in nature that play an important role within the global cycling of carbon and sulfur1,2,3. The SRB are known to possess two major lifestyles: sulfidogenic and syntrophic metabolism. In the presence of sulfate, SRB use it as the terminal electron acceptor during the oxidation of various products of primary fermentations and oxidize them to CO22,4. When sulfate is depleted, SRB in general ferment organic acids and alcohols, producing hydrogen, acetate and carbon dioxide and rely on hydrogen- and acetate-scavenging methanogens to convert these compounds to methane5,6. This working relationship of SRB with methanogens is understood as ‘syntrophy’ and has been considered because the heart of how methanogenic and other anaerobic microbial communities function7. A model syntrophic interaction involves lactate oxidation by Desulfovibrio vulgaris to supply acetate, CO2 and H2 as products, which the methanogen, Methanosarcina barkeri, can then further convert to CH48. The removal of H2 by M. barkeri provides a thermodynamically favorable condition (i.e., low H2 concentration) for the continued oxidation of lactate by D. vulgaris3,8. The advantage of having two different metabolic capabilities is that it raises the chances of survival of SRB in environments where electron acceptors could become depleted3. While the physiology of the symbiotic relationship of SRB and methanogens has been studied for several decades years3,9, relatively little is known about the genes and their expression dynamics associated with the syntrophic interactions, partially thanks to the shortage of suitable methodologies for measurements of biological properties in mixed-culture systems within the past. To address the difficulty , a transcriptomic analysis approach, which is in a position to differentiate transcripts from each of two species participated within the syntrophic relationship, was recently employed to match the gene expression profiles of D. vulgaris in sulfate-limited monocultures and in syntrophic dual-cultures with a hydrogenotrophic methanogen Methanococcus maripaludis10 and of D. vulgaris during its metabolic shift from syntrophic growth with M. barkeri to sulfidogenic growth11. The results showed that between the 2 lifestyles, several hundred genes including those encoding ATPase, hydrogenases and high-molecular-weight cytochrome were differentially regulated, suggesting their potential roles to syntrophic growth relationship in D. vulgaris11,12. Interestingly, a gene cluster encoding several functionally unknown lipoproteins and membrane-bound proteins (DVU0145 to DVU0150) was found up-regulated in syntrophic dual-cultures when compared with the monocultures10 and down-regulated when D. vulgaris cells were shifted from syntrophic to sulfidogenic metabolism11, suggesting they may be involved in syntrophic metabolism. However, so far no further investigation on these genes have been conducted. Single-cell microbiology has attracted significant attention as more evidence suggested that even isogenic populations of microorganisms could have substantial cell-to-cell heterogeneity at both cellular and molecular levels12,13,14,15,16,17. For example, a RT-qPCR analysis of individual cells from the identical Escherichia coli population showed that the expression level of highly expressed the 16S rRNA gene could vary up to ~32-fold between single cells of the same population18. In addition to micro-scale environmental differences, it is currently known that gene-expression stochasticity, or noise, once amplified through generations, could eventually generate heterogeneity at the cellular level in a clonal bacterial population17,19,20. The significant gene-expression heterogeneity observed for a microbial population suggests that by simply harvesting and analyzing mRNA or proteins from whole populations, it may not be able to capture the unique patterns of gene expression related to distinct functional subpopulations. When it comes to mixed cultures, single-cell based analysis may be more valuable as the heterogeneity within a mixed population could be even higher as different types of cells with distinct metabolic profiles, interaction and stress responses, are co-cultivated within one culture21. Although single-cell genomics has been applied to a handful of symbiotic systems, including bacterial symbionts of marine sponges, insects (grasshoppers, termites)22, to our knowledge, the single-cell based gene-expression analysis has thus far not been applied to any syntrophic microbial system and therefore the dynamics of organic phenomenon and metabolic status in cells of syntrophic mixed cultures reminds unclear. In this work, we applied a single-cell RT-qPCR approach to reveal gene-expression heterogeneity during a model syntrophic system of Desulfovibrio vulgaris and Methanosarcina barkeri, as compared with the D. vulgaris monoculture. Using the optimized primers and single-cell analytical protocol, we quantitatively determine geneexpression levels of 6 selected target genes in each of the 120 single cells of D. vulgaris isolated from its monoculture and dualculture with M. barkeri. The results demonstrated very significant cell-to-cell gene-expression heterogeneity for the chosen D. vulgaris genes in both the monoculture and therefore the syntrophic dual-culture. Interestingly, no obvious increase in gene-expression heterogeneity for the chosen genes was observed for the syntrophic dual-culture in comparison with its monoculture, although the community structure and cell-cell interactions have become more complicated in the syntrophic dual-culture. In addition, the single-cell RT-qPCR analysis also provided further evidence that the gene cluster (DVU0148-DVU0150) could also be involved syntrophic metabolism between D. vulgaris and M. barkeri. Finally, the study validated that single-cell RT-qPCR analysis might be a valuable tool in deciphering gene functions and metabolism in mixed-cultured microbial communities.

सार विस्तारित

Biodiversity Congress 2018: Strengthening indigenous informal seed system in Southeast Asia

Ricky M Bates

Seed may be a fundamental agriculture input and access to locally adapted, quality seed is an important component of sustainable crop production. In much of the developing world, informal seed systems, like farmer-to-farmer exchanges and farmer self-saved seed, are critical components of resource poor farming systems. Indeed, planted seed from this informal system comprise the bulk of planted acreage in many regions of the planet . This local seed production and distribution facilitates maintenance of crop biodiversity by preserving in situ locally adapted varieties and by broadening the genetic base of production with multiple varieties adapted to specific production systems and micro-climates. These informal seed systems are also critical for seed and food security during periods of instability or natural disaster, including changing environmental conditions. A rich diversity of underutilized species functions within informal seed systems in Southeast Asia and represents a valuable resource for the development and improvement of crop species. Current efforts to conserve, improve and disseminate indigenous species are failing or insufficient. To optimize these informal seed systems, research has been conducted to better understand their germplasm characteristics, distribution pathways and gatekeepers and to improve local stakeholder access to seed information and value chains.
In 2011, the number of hungry people in the world surpassed one billion for the first time (Food and Agriculture Organization of the United Nations [FAO], 2011). Disasters such as the famine in the Horn of Africa and a mega-typhoon scything through the Philippines, in conjunction with rapidly rising food prices worldwide, have further reduced food security for millions of people. Despite a declining trend in the proportion of hungry people in the world in the last 30 years of the 20th century, since 2004 there has been a reversal of this trend (FAO, 2011). With the world’s population forecast to rise to 9 billion by 2050, Malthusian speculation has once again emerged with concerns that the number of hungry and malnourished people will continue to rise and outpace food production increases, resulting in a food insecure world. Food security was first defined at the 1974 World Food Summit as “availability at all times of adequate world food supplies of basic foodstuffs to sustain a steady expansion of food consumption and to offset fluctuations in production and prices” (United Nations, 2003, “Official concepts of food security,” para. 2), reflecting the main supply-side concerns at the time in the context of repeated famines, hunger, and food crises around the world. Since then, the concept has been re-defined numerous times, and generally accepted definitions of food security have adopted a threefold axis of availability, accessibility, and utilization of food (FAO, 2008). More recently, concerns about the stability of the food system and its relation to the environment have also been incorporated. Food security concerns rose rapidly to the forefront of the global agenda beginning with the food price crisis of 2007–2008. Food riots from Haiti to Mozambique brought the realization that the world hunger problem had not yet been solved. At the 2009 L’Aquila summit, the G8 nations acknowledged the need to tackle food insecurity head on, and pledged $22bn to set up the Global Agriculture and Food Security Program (GAFSP), administered jointly by the World Bank, International Monetary Fund, and G8 governments (United States Treasury, 2011). Renewed emphasis thus is now being placed on addressing food security at its roots — in regions and locales where undernourishment is king and many households live daily on the edge. Arguably the most important focus of present-day food security concerns is resource-poor smallholder farmers in developing or emerging economies. The vast majority of the world’s one billion undernourished people resides in Asia or sub- Saharan Africa and depends daily on small farm output for their livelihood and/or their food. This farm output is dependent upon many inputs, of which seed is one of the most critical. Without available or accessible seed, many households in developing nations are exposed to the potential of becoming food insecure. The informal seed system contrasts with the formal seed system, which involves governmental, institutional, or private control of the whole gamut of seed activities, including but not limited to breeding, multiplication, processing, and storage. Such formal systems are typically vertically organized with specific structures in place for production and distribution of seed and operate on generally strict and similar principles across the globe (Almekinders, Louwaars & de Bruijn, 1994). These formal systems are the source of modern varieties and certified seed (Sperling & McGuire, 2010), usually developed through modern breeding technologies and often tested on research farms. Research and extension projects to conserve and promote neglected and underutilized species within these informal seed systems have resulted in: (1) surveys of key indigenous crops and collection of local crop knowledge, (2) training and development of regional community-based seed banking enterprises, (3) seed quality conferences including seed exchange activities and (4) improved human and institutional capacity, strategically focused on entrepreneurial women.

सार विस्तारित

Biodiversity Congress 2018: Vulnerability of womenâ??s livelihoods and their coping mechanisms in face of climate change in coastal regions of Bangladesh

Salim Momtaz

Bangladesh is frequently cited as a country that is most vulnerable to climate change. In Bangladesh, most of the adverse effects of climate change occur in the form of extreme weather events, such as cyclone, flood, drought, salinity ingress, river bank erosion and tidal surge, resulting in large scale damage to crops, employment, livelihoods and therefore the national well-being. Although it is generally stated that women are relatively more vulnerable than men in the context of climate change, few studies have been conducted to closely examine this statement, especially in Bangladesh. The present study, investigates the structure of women’s livelihoods, livelihood vulnerabilities and coping capacity in the context of climate variability and change in a disaster vulnerable coastal area of Bangladesh. Utilizing the concepts of Sustainable Livelihood Framework (SLF) and Disaster Crunch Model (DCM), this study allows for a greater understanding of these issues on the ground. The results show that the distribution of 5 livelihood capitals (human, natural, financial, social and physical) of girls are heavily influenced by several climatic events, like cyclones that periodically affect the region. Women also face several vulnerabilities in their livelihoods, including income, household assets, health, food security, education, water sources, sanitation and transportation systems, due to ongoing global climate change impacts. The results indicate that it is extremely important to instigate strategies to help build the adaptive capacity of women to reduce the burden created by their livelihood vulnerability. Very few studies have been conducted to explore the vulnerability of women in the context of climate change. This research addresses this absence by investigating the structure of women’s livelihoods and coping capacity in a disaster vulnerable coastal area of Bangladesh.


Definition of the Concepts
Vulnerability is that the condition determined by physical, social, economic and environmental factors or processes, which increase the susceptibility of a community to the impact of hazards (UN 2009). Vulnerability is ‘insecurity, the reverse of security’; it reflects "the characteristics of an individual or group in terms of their capacity to anticipate, cope with, resist, and get over the impact of a natural hazard.” It involves a mixture of things that determine the degree to which someone's life and livelihood is put in danger by a discrete and identifiable event in nature or in society. Vulnerability refers to exposure to contingencies and stress and difficulty in dealing with them. It has two components: i) an 'external' side of risks, shocks and stress to which a structure, individual, household, community or nation is subject; and ii) an 'internal' side of lack of resources to cope without damaging loss. A human condition is resulting from physical, social, economic and environmental factors which determine the livelihood and scale of damage from the impact of a given hazard.


Coping Strategies: In disaster management, coping means the trends and techniques where people gain their expected results by using their property. It is very much related with capacity. Strategies are often defined as a group of activities or mechanism by which individuals attempt to survive in disasters, recover their situation and develop their conditions after disaster.


Coastal Area: In this study, coastal area means the places situated beside the Bay of Bengal and many rivers of Bangladesh. The coastal areas of Bangladesh are facing the Bay of Bengal with an area of 47,201 sq. km. covering 19 districts: Bagerhat, Barguna, Barishal, Bhola, Chandpur, Chittagong, Cox’s Bazar, Feni, Gopalganj, Jessore, Jhalokati, Khulna, Lakshmipur, Narail, Noakhali, Potuakhali, Pirojpur, Satkhira and Shariatpur.
The research findings suggest that the distribution of livelihood capitals of vulnerable women in rural Bangladesh is heavily influenced by several climatic events, such as cyclones, floods and seasonal droughts that periodically affect the region. Women face several challenges in their livelihoods, including vulnerability to their income, household assets, lives and health, food security, education, water sources, sanitation and transportation systems, because of ongoing climate change impacts. The findings have important policy relevance for all involved in disaster and risk management, both within Bangladesh and the developing countries facing climate change impacts. Based on the research findings, it recommendations to improving the livelihoods of women in the coastal communities. Impacts of global climate change on the livelihoods of coastal people within the south-western a part of Bangladesh. This study has been conducted by using quantitative method with semi-structured interview questionnaire for data collection in purposive manner. The paper examines the impacts of global climate change on agricultural productivities, food securities and institutional challenges that the coastal people face. This paper finds that the frequency and severity of climate change have increased in recent years, that threat on food securities by inundating low agriculture land, restricting economic activities, decreasing employment opportunities, expanding different health diseases, destructing houses, crops and other infrastructures in Bangladesh. The findings indicate that the foremost global climate change induced vulnerable and risky people are women, children, elderly and disabled people as they can't easily deal with the unfavorable environment duringclimate change. There has not been conducted much inquiry about the impacts of global climate change , so policy makers can get comprehensive view about this concern by this study and implement policy for the survival of the climate change induced affected coastal people.

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Biodiversity Congress 2018: Impact of anthropogenic disturbance on anurans habitat and species diversity in Silago, Southern Leyte Philippines

Wilbert A Aureo Bohol

Statement of the Problem:
The combinations of natural and anthropogenic factors such as climate, geographic ranges and vegetation types are considered to have a significant influence on species distributions and diversity. The pattern of increase in habitat heterogeneity on the structure and composition of vegetation becomes complex if the niche diversity and species diversity increases. Moreover, several species of forest anurans are correlated with the number and quality of woody debris, litter depth and overstorey canopy closure. The Philippines is one of the few countries in the world that is covered by rain forest. It is also considered as one of the world’s mega diverse countries that host a large share of endemic flora and fauna. However, due to the conversion of forests to marginal agriculture, commercial agriculture and timber plantations, these forest resources are disappearing at an alarming rate. Filipino farmers who are poor and lack employment opportunities in the lowland migrate to the upland areas where they cut down secondary forest and practice slash and burn farming. Silago forest is one of the remaining primary forests in the region. However due to rampant and uncontrolled hunting of wildlife and habitat destruction caused by slash-and-burn cultivation or kaingin contributed by residents both within and outside the communities, threat on biodiversity increases (Ceniza et al., 2011). In Barangays Imelda, Katipunan and Catmon, slash-and-burn cultivation is being practiced by the residents. This is their major source of livelihood because many of them do not own land in the alienable and disposable areas. Thus, the current study examines the impact of ecological disturbance to habitat condition (i.e. rainfall, temperature, relative humidity, vegetation structure, litter depth, and woody debris) and anurans species and population due to anthropogenic activity.


Methodology & Theoretical Orientation:
Establishment of plots followed the method of Williams (2004). Anurans collection was done at early morning 6:00-9:00 am and evening at 7:00-10:00 pm. The Visual Encounter Survey was used to search high potential areas throughout the sampling sites. These are on the surface and under rocks, logs, trees, and other debris within each established plot. Herbaceous layer, understory, canopy vegetation were identified (genus level) and counted. Each CWD was rated on its degree of decomposition ranging from 1 (sound, intact, no rot) to 5 (no structural integrity, soft, powdery). Also, litter depth in each quadrat was measured using a meter stick by randomly selecting three points of location per quadrat. Temperature, rainfall and relative humidity were measured using thermometer, improvised rain gauge and psychro-dyne respectively. PROC univariate test for data normality and heterogeneity was done using statistical analysis system version 9.1 (SAS, 2003). PROC GLM was also used to check effect for the anthropogenic disturbance with habitat condition parameters and species richness and diversity. Finally, Duncan Multiple Range Test (DMRT) was employed to test the factors. All data were tested for normality and heterogeneity using PROC Univariate of Statistical Analysis System version 9.1 (SAS, 2003). PROC GLM (general linear model) procedure was initially performed to check for effects of ecological disturbance on microclimatic factors (i.e., temperature, relative humidity, and rainfall), habitat structure (i.e., litter depth and quantity and quality of coarse woody debris), vegetation structure (i.e., herbaceous layer, understorey, and climax strata), and species richness of anurans. The final models for each response variables were analyzed including but those with only significant main factors effect for anurans. Duncan multiple range test (DMRT) and Least square differences (LSD) were carried out to compare means of independent variables with significant variations at p≤0.05


Both the species richness and diversity in the primary forest is significantly (p≤0.05) different from slash-and-burn cultivation. Frog population increases steadily during natural succession, attaining similar characteristics to those from mature forest after regeneration following slash-and-burn cultivation. Meanwhile, when the habitat starts to stabilize its condition (that is conducive to anurans), the frog species starts to increase dramatically. Meanwhile, the total number of species in the primary forest, secondary forest, and slash-and-burn cultivation were S=7, S=4, and S=0, respectively. The result is consistent with the study of Mallari et al. (2013) in Silago forest where they observed a maximum number of anurans species of S=4. Mallari et al. (2013) reported that the number of species is correlated to the degree of disturbance. Furthermore, the density of frogs observed was eight (8) frogs per 100m2 in the primary forest while four (4) frogs per 100m2 in the secondary forest and zero (0) frog in the slash-and-burn cultivation. This supports the study of Sluys et al. (2007) that the density observed in the rainforest in Brazil is four (4) frogs per 100m2. Moreover, it was observed that there were four (4) species of frogs (i.e, Platymantis corrugatus, Occidozyga laevis, Platymantis sp., and Staurois sp) found in primary forest that were not observed in the secondary forest and slash-and-burn cultivation while Hylarana erythaea (an introduced and invasive species) was observed in the secondary forest and was not observed in the other two sites. The study also showed that microclimatic parameters, microhabitat and vegetation structures appear to be the factors influencing habitat condition of anurans which significantly (p≤0.05) affect anurans species richness and diversity. 


Conclusion & Significance:
The results of the study affirm that anthropogenic disturbance alters anurans habitat condition, thereby, affecting its species richness and diversity. It is worth mentioning that there was a considerable reduction (p≤0.05) of anurans species richness and diversity in the primary forest, secondary forest and slash-and-burn cultivation. Moreover, the study suggests that microclimatic parameters, microhabitat and vegetation structures appear to be the factors influencing habitat condition of anurans which significantly (p≤0.05) affect anurans species richness and diversity.

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Biodiversity Congress 2018: Butterfly-flower interactions and biodiversity in changing environments

Aluri Jacob Solomon Raju

Butterflies occupy a vital position in the ecosystem and are useful as indicators of environmental change. Their occurrence depends on the climatic dicta, the presence of suitable caterpillar foods and appropriate adult nectar sources or other food, suitable arenas for flight and courtship. These insects enhance the aesthetic value of the environments by their exquisite wing colors. Butterflies are the wild indicators of the ecosystem; these insects tell us everything about the healthier ecosystem. These are effective pollinators, butterflies visit the flower to eat nectar and this is often interdependent relationship. Some species of butterflies migrate over long distance; carry pollen to be shared across plants which are far aside from each other . This migration of pollens induces genetic variation in plants species and gives a better chance at survival against different disease. These insects also provide food for other organisms, for example; birds, reptiles amphibians and also acts as biological pest control. But the population of those insects decline rapidly thanks to human activities, habitat destruction, uses of pesticides and unawareness of individuals about the importance of flying flowers. They require a continuous supply of food sources, especially nectar sources from a number of plant species. In this context, floral morphological and nectar characteristics are important for visitation by butterflies. Nectar plays an important role in the nutrition of adult butterflies. Nectar is a highly enriched food resource consisting of carbohydrates, amino acids, lipids, antioxidants, alkaloids, proteins, vitamins, salts, etc. But, all these nutrient chemicals are not found in a single floral nectar source and hence flower-visiting butterflies should pay visits to different floral nectars to acquire all the required nutrients. The butterfly interactions with the flowers of certain plant species are going to be detailed. Plant species which facilitate foraging by butterflies show certain floral traits adapted for butterfly foraging activity and within the process both get benefited. With accelerated deforestation and changing ecology and subsequent change in the environment, the butterflies appear to be struggling to get the required levels of quality nectar for survival during their adult life. The summer season is extremely crucial for butterflies since a couple of plants bloom during this era . The butterflies appear to be malnourished during adult life due to lack of enough nectar sources throughout the year due to changes in land use and climate. The butterfly plays a crucial role in ecosystems, acting as a pollinator, a food source and an indicator of the ecosystem's well-being. Butterflies play an enormous role in pollinating flowers that open during the day. Butterflies tend to favor big, colorful flowers that have a landing platform and gather pollen on their long, thin legs as they sip nectar from a flower. Butterflies are sensitive to climate change, such as pollination and habitat loss, and cause them to be more responsive. Therefore, an abundance of butterflies usually indicates a healthier ecosystem. Many butterfly species migrate over long distances as many as 3,000 miles. These migrations leave pollination across long distances and have increased human interest within the species. Butterflies contribute to ecosystem restoration because they provide pollination and a source of food. Increased butterfly populations may indicate a rise in plant diversity and other pollinator groups within restored areas. Butterflies are attractive addition to garden and more important insect than most of the people realize. As a wildlife indicator, butterflies tell us almost everything we'd like to understand about the health of an ecosystem Dobson, 2012. Swengel demonstrated that in ecosystem, plant and animal species sleep in sites with similar combinations of soil, topography, climate and geography. Some sorts of vegetation must be required for Butterfly species existence. Butterflies living especially place have particular habitat requirements. An interesting part of studying, localized butterflies is learning to find out the microhabitats they require. In ecosystem natural events either favor or reduce butterfly population’s characteristics of microhabitats occurring therein ecosystem. Butterflies maintain the ecosystem by acting as pollinator, prey, biological pest control, induce genetic variation in plants, and enhance environmental beauty, reduce the extent of CO2 in air. But butterfly population is decline rapidly and it's suggest that greater emphasis should be placed on management of habitat and better integration of protected areas. Ecologist use butterflies as model organisms to study the impact of climate change, habitat loss.

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