Hemanta Kumar Gogoi

Fatty acid profiling and molecular characterization of some freshwater microalgae from India with potential for biodiesel production.

We determined the fatty acid compositions of six species of freshwater microalgae belonging to the Chlorophyta, which were isolated from freshwater bodies in Assam, India. All six microalgae -Desmodesmus sp. DRLMA7, Desmodesmus elegans DRLMA13, Scenedesmus sp. DRLMA5, Scenedesmus sp. DRLMA9 Chlorella sp. DRLMA3 and Chlorococcum macrostigmatum DRLMA12-showed similar fatty acid profiles 16:0, 16:4, 18:1, 18:2, and 18:3 as major components. We also compared fatty acid compositions during the late exponential and stationary growth phases of D. elegans DRLMA13 and Scenedesmus sp. DRLMA9 in BG11 medium. We observed enhanced percentages of total saturated and monounsaturated fatty acids with a concomitant decrease in polyunsaturated fatty acid content upon the prolonged cultivation of both microalgae. Distinct morphological features of microalgal isolates were determined by scanning electron microscopic (SEM) studies. An ornamented cell wall was found in D. elegans DRLMA13, which is characteristic of small spineless species of Desmodesmus. The isolated microalgae were further distinguished through analysis of internal transcribed spacer 2 (ITS2) secondary structures and compensatory base changes (CBCs). Analysis of CBCs showed the relatedness of Chlorella sp. DRLMA3 with other Chlorella-like organisms, but it does not belong to the clade comprising Chlorella sensu stricto, which includes Chlorella vulgaris. The CBC count between Scenedesmus sp. DRLMA9 and other species of Scenedesmus provides evidence that this isolate represents a new species.

Antagonistic Potential of Native Trichoderma viride Strain against Potent Tea Fungal Pathogens in North East India.

Indigenous strains of Trichoderma species isolated from rhizosphere soils of Tea gardens of Assam, north eastern state of India were assessed for in vitro antagonism against two important tea fungal pathogens namely Pestalotia theae and Fusarium solani. A potent antagonist against both tea pathogenic fungi, designated as SDRLIN1, was selected and identified as Trichoderma viride. The strain also showed substantial antifungal activity against five standard phytopathogenic fungi. Culture filtrate collected from stationary growth phase of the antagonist demonstrated a significantly higher degree of inhibitory activity against all the test fungi, demonstrating the presence of an optimal blend of extracellular antifungal metabolites. Moreover, quantitative enzyme assay of exponential and stationary culture filtrates revealed that the activity of cellulase, β-1,3-glucanase, pectinase, and amylase was highest in the exponential phase, whereas the activity of proteases and chitinase was noted highest in the stationary phase. Morphological changes such as hyphal swelling and distortion were also observed in the fungal pathogen grown on potato dextrose agar containing stationary phase culture filtrate. Moreover, the antifungal activity of the filtrate was significantly reduced but not entirely after heat or proteinase K treatment, demonstrating substantial role of certain unknown thermostable antifungal compound(s) in the inhibitory activity.

Diversity of Cultivable Midgut Microbiota at Different Stages of the Asian Tiger Mosquito, Aedes albopictus from Tezpur, India

Aedes aegypti and Ae. albopictus are among the most important vectors of arboviral diseases, worldwide. Recent studies indicate that diverse midgut microbiota of mosquitoes significantly affect development, digestion, metabolism, and immunity of their hosts. Midgut microbiota has also been suggested to modulate the competency of mosquitoes to transmit arboviruses, malaria parasites etc. Interestingly, the midgut microbial flora is dynamic and the diversity changes with the development of vectors, in addition to other factors such as species, sex, life-stage, feeding behavior and geographical origin. The aim of the present study was to investigate the midgut bacterial diversity among larva, adult male, sugar fed female and blood fed female Ae. albopictus collected from Tezpur, Northeastern India. Based on colony morphological characteristics, we selected 113 cultivable bacterial isolates for 16S rRNA gene sequence based molecular identification. Of the 113 isolates, we could identify 35 bacterial species belonging to 18 distinct genera under four major phyla, namely Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Phyla Proteobacteria and Firmicutes accounted for majority (80%) of the species, while phylum Actinobacteria constituted 17% of the species. Bacteroidetes was the least represented phylum, characterized by a single species- Chryseobacterium rhizoplanae, isolated from blood fed individuals. Dissection of midgut microbiota diversity at different developmental stages of Ae. albopictus will be helpful in better understanding mosquito-borne diseases, and for designing effective strategies to manage mosquito-borne diseases.

Vegetative and Yield Attributes of Okra and Naga Chilli as Affected by Foliar Sprays of Vermiwash on Acidic Soil

In view of concerns raised about economic and ecological consequences of agricultural chemicals, organic amendments, such as vermiwash, have been considered appropriate strategies for crop improvement. However, research work evaluating the efficacy of foliar sprays of vermiwash in vegetable crops on acidic soils is quite limited. The present investigation, therefore, was carried out to evaluate the effect of different concentrations of vermiwash (VW) on okra (Abelmoschus esculentus L.) under field conditions on acidic soil. We also evaluated the response of Naga chilli (Capsicum assamicum) to foliar spray of 20% concentration of vermiwash. Results revealed that the application of VW significantly improved the vegetative and yield attributes of both the test crops. In okra, 20% VW exhibited the largest increase in marketable weight among all the treatments. The plants of Naga chilli receiving foliar spray of 20% VW registered a 27.47% increase in shoot height and a 11.93% increase in chlorophyll content (SPAD) as compared with control. In regards to yield attributes of the Naga chilli, foliar spray of 20% VW resulted in a 23.07 % increase (significant at P = 0.05) in number of seeds per fruit and a 43.47% increase (significant at P = 0.05) in average fruit weight in comparison with control. We suggest that foliar spray of 20% concentration of vermiwash could considerably improve the growth and yield of okra and Naga chilli on acidic soil.

Detection of human papillomavirus in women attending Pap cervical screening camp at a peripheral hospital of North-Eastern India

Human papillomavirus (HPV) associated cervical cancer is the leading cause of deaths in India. However, cytological/HPV screening may result in early detection of cervical cancer, resulting in early treatment and reduced mortality. Although reports related to general population is available, data on HPV prevalence among women attending AFMS health care facilities is scarce. Cervical samples were collected for cytological staining by Pap test and molecular detection by PCR, genotyping by HPV specific primers and sequencing. Apart from finding of atypical cells of undetermined significance (ASCUS) in one subject, no evidence of malignancy was observed. A high prevalence of HPV was found in this study group, which was intermediate between previous reports from general population and cervical cancer patients. All the subjects had infection of high risk HPV type16. HPV prevalence was found similar between different age groups. Although, none of the study subjects had malignant changes, but due to high prevalence of high risk HPV infection and other associated risk factors, these subjects might be at an elevated risk of developing cervical cancer. Regular follow-up of these patients who were detected HPV positive are required to screen for cervical malignancy.

Algal Wealth of Northeast India

Northeast India is a treasure trove of floral and faunal diversity and is a mega biodiversity hotspot. Different types of freshwater bodies such as ponds, rivers, lakes and beels can be found in this region which abounds in microalgae of varied forms. The climatic condition of this region is favourable to the growth of freshwater microalgae as the rainfall in this region is distributed throughout the year and the waterbodies do not go dry. Few studies have been undertaken to explore the algal wealth of this region which has hitherto remain unexplored and untapped.

High Frequency β-glucuronidase Reporter Gene Expression in Shoot Tip, Leaf, and Hypocotyl Explants of Jatropha curcas L.

Development of a suitable genetic transformation system is the backbone of transgenic technology for efficient recovery of Jatropha curcas plants with desirable traits. Although in vitro plant regeneration protocols for shoot tip, leaf, and hypocotyl explants of J. curcas have been reported, these protocol have not been translated into efficient genetic transformation systems. The objective of this study was to standardize the parameters influencing transient β-glucuronidase reporter gene expression following Agrobacterium-mediated genetic transformation using shoot tip, leaf, and hypocotyl explants of Jatropha curcas. Disarmed Agrobacterium tumefaciens strain EHA105, harboring pCAMBIA2301 carrying neomycin phosphotransferase (nptII) as a selectable marker and the β-glucuronidase (GUS) as a reporter gene, were used for transformation. Frequencies of GUS gene expression of 86.7%, 78.3%, and 74.2% were obtained for leaf, hypocotyls, and shoot tip explants, respectively. The transgenic nature of the kanamycin-resistant explants was also confirmed by using polymerase chain reaction (PCR) assay. Because, to date, there is no report on Agrobacterium-mediated transformation of shoot tip, leaf, and hypocotyl explants of Jatropha curcas, our findings/protocol should be useful for recovering stable transgenic Jatropha curcas plants from these explants.

Molecular Farming for Production of Biopharmaceuticals and Edible Vaccines in Plants

Production of recombinant proteins such as edible vaccines, recombinant subunit vaccines, antibodies and other medical proteins in plants is referred to as molecular farming. Plants, as expression platform, have several advantages over mammalian or microbial systems such as low cost of production, fast scalability, absence of pathogenic microbes and their capability to synthesise complex proteins. This involves identification and isolation of the gene of a pathogen encoding antigenic protein and preparation of a suitable construct followed by its introduction to a suitable plant host system either through Agrobacterium-mediated or direct gene transfer technique for expression of the protein of interest. The plant parts of the transgenic plant containing the antigen are fed raw or the protein is extracted and administered. The cultivation of these plants needs to be done in a greenhouse or under in vitro condition in order to negate environmental and biosafety issues. Biofarming offers great opportunity to the pharmaceutical industry for production and supply of medicines at an affordable cost, particularly to the developing countries.

Pharmaceutical scope of a phytochemically unexplored medicinal plant, Sarcochlamys pulcherrima (Roxb.) Gaud.: A review.

Sarcochlamys pulcherrima (Roxb.) Gaud. is widely used as traditional medicine and food by different tribes and communities of Assam in India and in neighboring countries. Recent studies conducted in our laboratory showed the broad-spectrum antimicrobial and antioxidant activities of its crude extract and different solvent fractions and detected the presence of phenolics, flavonoids, saponin, and acidic compounds. This review gives a bird′s eye view of the traditional uses of S. pulcherrima as food and medicine based on the information gathered by personal interaction with the people of different places of Assam as well as the investigations made on its ethno-botanical claims, biological activities, and other aspects by various workers since years till date and highlight the prospects of future research.

Isolation and determination of deoxynivalenol by reversed-phase high-pressure liquid chromatography

Deoxynivalenol (DON) is a mycotoxin produced by food contamination. It is a pharmacologically active compound that acts on the serotonin receptor, leading to several neuroendocrine and hematological disorders. In this article we describe a simple, accurate, and sensitive method for the quantification of DON. DON was quantified using a Phenomenex® ODS analytical C18 column (150 mm × 46 mm, 5 μm) with a mobile phase composed of mixture of water-acetonitrile-methanol (5:4:1, v/v/v) at a flow rate of 1.5 ml/min and at 254 nm in an ultraviolet (UV) detector The method has been validated with isolated samples of DON and provides a tool for the control of substandard and counterfeit commercial food products.