Botany

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    The Groundwater Geochemistry and the Human Health Risk Assessment of Drinking Water in an Area with a High Prevalence of Chronic Kidney Disease of Unknown Etiology (CKDu), Sri Lanka
    (Journal of Chemistry, 2021) Botheju, W. S. M.; Liyanage, J. A.; Kannangara, S. D. P.; Corchado, J.
    Chronic kidney disease of unknown etiology (CKDu) has become an alarming health issue in Sri Lanka. ,e disease is more notable among farming communities and people who consume groundwater as their main source of drinking water. To assess the possible links between drinking water chemistry and expansion of CKDu, the study was compared with hydrogeochemical data of drinking water sources in a CKDu prevalent area (Girandurukotte GND, Badulla District) and a reference area (Dambethalawa GND, Ampara District) in Sri Lanka. Based on the results, nephrotoxic heavy metal (Cd, Cr, Pb, and As) concentrations were significantly higher in the CKDu prevalent site than the reference area, compromised the harmful consequences to the people in the CKDu hotspot. Results of the inverse distance weighted (IDW) interpolation tool indicated the nephrotoxic heavy metals contents including Cd, Pb, As, and Cr in CKDu hotspot were changed in the ranges of 9.78–187.25 μg/L, 0.08–0.66 μg/L, 20.76–103.30 μg/L, and 0.03–0.34 μg/L. ,e random distribution patterns were shown by the result in Moran’s index values. Noteworthy, the results have emphasized a strong association between fluoride and water hardness. ,e frequency of occurrence above the threshold limit of fluoride was 28% in non-CKDu water samples, while 81% in CKDu prevalent sites. ,e hardness values in the CKDu prevalent site indicated “moderately hard water,” while the non-CKDu area indicated the “soft water.” Furthermore, this paper quantified overall water quality and heavy metal contamination and assessed the human health risks associated with drinking water. According to the results of the water quality index, 90% of the samples in the CKDu prevalent area were classified as “poor water” and “very poor water” for drinking purposes, while 73.33% of the samples in the non-CKDu area were “good” and “excellent” for drinking usage. Calculated chronic daily intake (CDIoral) and hazard quotient (HQoral) of nephrotoxicants were higher in CKDu hotspot than the non-CKDu site. Besides, the hazard index (HI) values obtained for the CKDu prevalent area exceeding the acceptable limit (HI � 1) indicated potential health risks to the people in those areas. ,is study suggests that long-term exposure to nephrotoxic heavy metals, water hardness, and fluoride present in drinking water may threaten human health and affect kidney functions. ,erefore, regular monitoring and better management of water supplies in CKDu prevalent areas are essential to determine the contamination load and reduce the health impacts due to excessive and longterm exposure to the nephrotoxicants.
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    Spatial Variation in Trophic Structure of Dominant Fish Species in Lake Dongting, China during Dry Season
    (Water, 2018) Yu, J.; Guo, L.; Zhang, H.; Xu, J.; Hu, H.; Xue, T; Luo, C.; Yi, C.; Hu, Y.; De Silva, K.; Xie, P.
    Understanding trophic interactions in food webs is crucial to revealing the transfer of substances and energy from primary food sources to consumers in aquatic ecosystems. We hypothesize that the trophic structure of consumers can be significantly affected by primary food sources (pelagic, benthic, and littoral sources) through complex trophic interactions. This study used stable isotope analysis and Bayesian mixing models to estimate the trophic levels of fish consumers and the contributions of primary food sources in the three sub-lakes (Eastern, Southern, and Western Dongting) of Lake Dongting, which have different physical and chemical parameters of water, fish species diversity, and plankton (phytoplankton and zooplankton) density. Results showed the differences in community structures of fish among sub-lakes. Fish trophic levels were significantly higher in Eastern Dongting than those in the two other areas. The contributions of primary food sources to fishes were as follows: the pelagic source was the main basal food source in Eastern Dongting, and littoral and pelagic sources played equally essential roles in Southern Dongting; fishes in Western Dongting relied on more benthic source to growth than those in the two other regions. This study can fill gaps in our knowledge of the influence of the underlying food available on trophic structure of consumers by exploring the role of primary food sources and making the trophic structure of consumers in the aquatic food web highly complicated and diverse through control of the distribution of primary food sources.
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    Substrate characteristics and species diversity of marine angiosperms in a micro-tidal basin estuary on the west coast of Sri Lanka
    (Sri Lanka Journal of Aquatic Sciences, 2010) De Silva, K.; Amarasinghe, M.
    Diversity of marine angiosperm species (seagrasses) at Kadolkele in Meegamuwa (Negombo) estuary was studied with a view to understanding the effect of substrate characteristics on diversity. Seagrass samples were obtained along three line transects, laid perpendicular to the shoreline at 20 m intervals. Shannon-Wiener index was used to determine the species diversity of seagrasses in the study site at Kadolkele that was divided into three strata, demarcated by the distance, i.e. 0-10 m, 10-20 m and 20-30 m from the shoreline. Comparison of Shannon-Wiener index values indicated that the diversity of first stratum close to the shoreline was significantly different from that of the other two among which no significant difference was found to occur. Substrate pH, soil electrical conductivity, organic mater content and particle size distribution were measured from the substrate samples taken from each stratum. No statistically significant difference was observed with pH (3.92-6.82) and particle size distribution among the three strata. Soil electrical conductivity and organic matter content of stratum 3 however, was significantly different (p< 0.05) from the other two strata. Kadolkele seagrass bed consisted of two species and Halodule pinifolia (5822 shoots m-2) dominated over Halophila ovalis (1030 shoots m-2). The area adjacent (0-3 m) to the mangroves at the shoreline was devoid of seagrasses and H. ovalis was absent in stratum 1, indicating that substrate characteristics have a marginal effect on the species richness of the seagrasses. Although species richness was similar in the other two strata, higher (Shannon) evenness (0.231), despite the relatively low abundance in stratum 2, contributes to its higher species diversity. Present study therefore documents the subtle habitat partitioning of co-existing marine angiosperm species in a limited area in Meegamuwa estuary.
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    THE OTTER AS AN UMBRELLA SPECIES IN CHINA
    (International Otter Survival Fund, 2021) DE SILVA, K.H.W.L.
    The aim of this survey was to assess the current presence of otter along the River Dee, in Aberdeenshire, Scotland, through a series of spot-checks for field signs indicating otter activity along the riverbanks carried out from its upper reaches at the White Bridge in the Forest of Mar down to the coast at Greg Ness (approximately 125km). Spraint sites were the most abundant field signs observed along the course of the River Dee, with a total of 208 spraint sites found, the majority of which consisted of fresh or recent spraints (n = 162; 77.9%). The fresh or recently deposited spraints were found throughout upper, mid and lower regions of the River Dee surveyed. Both in situ and laboratory-based spraint analysis was performed to give an index of the diet of otters utilising the River Dee. The Salmonids (Salmon and Trout species) were the dominant prey item observed in the spraints along the River Dee but mammal remains were the dominant prey item found in spraints on the tributaries of the River Dee. Eel (Anguilla anguilla) remains were more prevalent than salmonids from spraints on the tributaries. Mammal remains were the most frequent non-fish items found in all spraints observed in this survey. Other non-fish items included bird, amphibian and crab remains.
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    The spray of essential oils with passive modified atmosphere packaging to control stem-end rot of mango 'Karutha Golomban'
    (lnternational Society for Horticultural Science, lll Asian Horticuttural Gongress 'AHC2020, 2020) Kodituwakku, T. D.; Abeywickrama, K.,; Karunanayake, K. O. L. C.
    'Karutha Cotomban' mango is more prone to stem-end rot (SER) disease that causes substantial postharvest losses in quality as well as quantity. The objective of this study was to use aqueous emulsions of basil (1.6 pL/mL), clove (2.0 pL/mL), cinnamon leaf (2.0 pL/mL) and cinnamon bark (1.6 pL/mL) oils as sprays with passive modified atmosphere packaging (MAP) in low density polyethylene (LDPE) bags qs_ a bio-s_afe strategy to control SER of 'Karutha Colomban' mango stored at 12 - 14 "C and 85 - g0% of retative humidity. Distilled water and 0.1% (w/v) carbendazim treatments were used as negative and positive controls respectively. ln-package respiratory gases were measured during storage for B days. Pathological, physicochemical, sensory evaluation and feel color of mango were assessed after transferring to ripening at the end of the storage period. All essential oil treatments combined with passive MAP have significantly reduced SER severity of mango to 0.3 ' 1.1% when compared to the negative controlwithout adversely affecting the physicochemical, sensory properties anl peel color. Mango fruits treated with basil, clove and cinnamon leaf oils obtained a slighily higher preference by the sensory panelthan other treatments. ln-package 02 concentration was at 3.8 - 5.8%, while CO2 was at 4.3 - 5.0% at the end of the B-day storage period. Respiratory gas levels attained a steady state equilibrium which resulied'in extending the shelf life by reducing the metabolism of both commodity and associated microorganisrns. Further, current treatments can be commercialized as eco-friendly treatment strategies to be used during transportation and storage of mango in local trade within one week and for exportation via air cargo that takes approximately 2 - 3 daYs.
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    Potential impact of predicted sea level rise on carbon sink function of mangrove ecosystems with special reference to Negombo estuary, Sri Lanka
    (Global and Planetary Change, 2018) Perera, K.; De Silva, K.; Amarasinghe, M.
    Unique location in the land-sea interface makes mangrove ecosystems most vulnerable to the impacts of predicted sea level rise due to increasing anthropogenic CO2 emissions. Among others, carbon sink function of these tropical ecosystems that contribute to reduce rising atmospheric CO2 and temperature, could potentially be affected most. Present study was undertaken to explore the extent of impact of the predicted sea level rise for the region on total organic carbon (TOC) pools of the mangrove ecosystems in Negombo estuary located on the west coast of Sri Lanka. Extents of the coastal inundations under minimum (0.09 m) and maximum (0.88 m) sea level rise scenarios of IPCC for 2100 and an intermediate level of 0.48 m were determined with GIS tools. Estimated total capacity of organic carbon retention by these mangrove areas was 499.45 Mg C ha− 1 of which 84% (418.98 Mg C ha− 1) sequestered in the mangrove soil and 16% (80.56 Mg C ha− 1) in the vegetation. Total extent of land area potentially affected by inundation under lowest sea level rise scenario was 218.9 ha, while it was 476.2 ha under intermediate rise and 696.0 ha with the predicted maximum sea level rise. Estimated rate of loss of carbon sink function due to inundation by the sea level rise of 0.09 m is 6.30 Mg C ha− 1 y− 1 while the intermediate sea level rise indicated a loss of 9.92 Mg C ha− 1 y− 1 and under maximum sea level rise scenario, this loss further increases up to 11.32 Mg C ha− 1 y− 1. Adaptation of mangrove plants to withstand inundation and landward migration along with escalated photosynthetic rates, augmented by changing rainfall patterns and availability of nutrients may contribute to reduce the rate of loss of carbon sink function of these mangrove ecosystems. Predictions over change in carbon sequestration function of mangroves in Negombo estuary reveals that it is not only affected by oceanographic and hydrological alterations associated with sea level rise but also by anthropogenic processes, therefore the impacts are site specific in terms of distribution and magnitude.
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    Carbon Source dependent - anaerobic Soil Disinfestation (ASD) Mitigates the Sclerotial Germination of Sclerotinia Sclerotiorum
    (Tropical Plant Pathology (2020), 2020) Mahalingam, T.; Rajapakse, C.S.K.; Somachandra, K.P.; Attanayake, R.N.
    Though Sclerotinia sclerotiorum IS a well-studied plant pathogen that causes significant economic damage worldwide, sustain able and environmental friendly control methods are difficult to establish due to it wide host range, cosmopolitan distribution and production of recalcitrant structures that can survive in soil for a long time. The pathogen was found causing a severe disease incidence on cabbage in 2016 in Sri Lanka. It was hypothesized that a) isolates of the recent disease outbreak display cross resistance to commonly applied fungicides and b) carbon (C) source supplemented Anaerobic Soil Disinfestation (ASD) is effective in mitigating the germination of sclerotia. In vitro fungicide sensitivity assays showed large variation in mycelial growth inhibition indicating high adaptability of the population towards environmental fluctuations and management practices. Signatures of cross resistance were evident. ASD was carried out using cabbage (Brassica oleracea) and leek (Allium ampeloprasum) cull piles, durian (Durio zibethinus) peels and grass cuttings (Axonopus compressus) as C sources and determined the sclerotial viability. Cabbage and leek cull piles at rates of 60—100 mg/g soil completely inhibited sclerotial germination. Maintaining anaerobic condition along with C source amendments was found to be a critical step in mitigating the sclerotial germination. GC-MS analysis of the volatiles of cabbage leaves, leeks and durian further confirmed the presence of various bioactive compounds with potential antifungal activity. Therefore, in addition to elevated microbial activity in treatments, the volatiles of C sources may have helped mitigating sclerotial germination.
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    Screening Anti-Bacterial Activity of Endoi.Ichenic Fungi Collected From Negombo Lagoon Sri Lanka
    (Proceedmgs of the Postgraduate Institute of Science Research Congress. Sri Lanka, 2019) Weerasinghe, W.R.H.; Attanayake, R.N.; Weerakoon, G.; Paranagama, P.A.
    From the ancient past, natural products have been in use to fulfill a variety of human needs, from sustenance to pharmaceutical necessities. With the discovery of Endolichenic fungi (ELF) as a novel source prominent bioactiOt1es in recent years. a new trend has been created to explore more about these fascinating organisms, which live inside the lichen thallus asymptomatically. ELF isolated from the lichens collected from mangrove plants In Negombo lagoon's Kadol kale area (Lititude: 701 Longitude: were identitied using molecular techniques and were subjected to anti-bacterual assay. Ethyl acetate crude extracts of 18 identified endolichenic fungal strains were obtained and their anti-bacterial activities were tested against aerobic bactertal species Escherichia coli, Bacillus subtilis and Staphvlococcus aureus. The assay was carried out using agar well diffusion method using HI of the extracts (5 mg/ml) with Azithromycin as the positive control. The inhibition zone diameters (in cm) against E. coli were 1.2 for Phanerothaete chnsosporium. 1.2 for Xvlaria feejecnsis, ().9 for Gelasinospora seminuda, 0.9 for Chaetomium globosum and 1.5 for Curvularia lunata while Azithromycin as the positive control showed a diameter of 2.1. The inhibition zone diameters against B. subtilis were 1.0 for Cochliobolus sp., 1.0 for P. chnsosporium, 1.8 for X. feeyeensls, 1.7 for G. seminuda, 1 2 for C. globosum, 1.5 for Hvpoxvlon lividipigmentum, 2.0 for (Pennicillium sp), 2.2 for C. lunata, 0.9 for Lasiodiplodia theobromae and 2.4 for positive control. The inhibition zone diameters against S. aureus were 1.1 for P. chrvsosporium, 22 for X'. feejeensis, 1.0 for G. seminuda, 1.0 for Chaetomium globosum, 2.0 for (Pennicillium sp). 1.8 for Curvularia lunata and 2.2 for positive control. Out of the 18 fungal strains, 9 showed significant activity against the tested bacterial species while Endomelanconiopsis endophvtica, Neofusicoccum parvum. Ncofusicoccum occulatum. Hvpoxvlon anthochroum. Cvtospora xvlocarpi, Cerrena sp., Schi:ophvllum commune, Daldinia eschscholt:i, Nodulisporium sp. fungal strains did not show any inhibition. Further studies will be conducted to isolate compounds responsible for these inhibitions.
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    Characterization of Agrobacteriu/ll strains from agricultural soils of Bandarawela, Sri Lanka
    (First National Symposium of Sri Lanka Association for Mycology and Plant Pathology (SLAMPP), 2019) Somarathna, G.M.T.K.; Somachandra, K.P.; Jayalath, W.G.H.; Attanayake, R.N.
    Agrobacterium is a Gram negative, rod shaped, aerobic and motile soil inhabiting bacterium of the family Rhizobiaceae. It is well known as the causative agent of crown gall disease of many plant species around the world. However, not all the Agrobacterium strains are pathcvenic and can cause galls. Only the virulent strains cause crown gall disease on number of plant species and are found only in contaminated soils. These virulent strains of A. tumefaciens harbor Ti plasmids with transfer DNA (T-DNA) region and virulence (vir) genes that are responsible for the pathogenicity. virD2 gene codes for virD2 protein and the endonuclease domain of the virD2 protein cleaves T-DNA border sequences. The ipt gene is the T-DNA borne cytokinin synthesis gene. Therefore, the presence of virD2 gene and ipt gene are useful in identifying pathogenic strains of Agrobacterium. The major objective of this research was to determine whether agricultural soils of Bandarawela were contaminated with virulence strains of A. tumefaciens. Soil samples were collected and bacteria were isolated using soil dilution method, and cultured on Yeast Mannitol Acar supplemented with Congo red and on Yeast Extract Peptone Affar. Five pure cultures of putatively Agrobacterium were further characterized using morphological and biochemical tests including Gram staining, catalase test, citrate utilization test, sugar fermentation test and 3-ketolactose test. These testes were often used for the species level identification of A. tumefaciens. Out of five isolates four were rod shaped with rounded ends and were either single or in pairs. However, the other isolate was in chains and Iono rod shaped. Interestingly, all the isolates were positive for all the biochemical tests. However, these tests do not help differentiating the virulence strains. Molecular characterization of all the soil isolates were carried out using universal 16s rRNA primers and Agrobacterium specific primers targeting virD2 and ipt genes. PCR amplification with virD2 primers successfully amplified the targeted band of 224 bp in all five isolates while ipt produced the expected fragment of about 427 bp in three of the isolates. virD2 cene sequences of selected soil isolates were 100-99% similar to the tumefaciens of the GenBank accession CP032925 and CP032929 reported from Taiwan. According to morphological, biochemical, and molecular Characterization using virD2 and ipt genes it was confirmed that the soil in the inspected field of Bandarawela is contaminated with pathogenic strains of A. tumefaciens. Therefore, farmers should maintain awareness when cultivating susceptible plant varieties in these fields.
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    Sclerotinia sclerotiorum populations: clonal or recombining?
    (Tropical Plant Pathology (2019) 44:23–31., 2019) Attanayake, R.N.; Xu, L.; Chen, W.
    Sclerotinia sclerotiorum, a homothallic plant pathogen, undergoes sexual reproduction via haploid selfing (equivalent to clonal reproduction), and produces long-lasting surviving vegetative structures called sclerotia, enhancing clonal persistence and spread. Thus it is not surprising to detect clones of the species. Whether outcrossing can occur in the homothallic S. sclerotiorum remains unanswered. Early studies showed that S. sclerotiorum has a clonal population structure, consistent with its life history traits. However, recent studies using polymorphic and co-dominant molecular markers showed frequent genetic recombination, suggesting outcrossing. This review focuses on recent developments in population genetics studies related to detecting recombination, random association of alleles and dynamic mating type (MAT) alleles in Sclerotinia. Despite frequent reports of random association of alleles, the mechanisms for outcrossing in a homothallic species remain elusive. Recent intriguing findings are: the MAT genes in Sclerotinia are subject to inversion or deletion in every meiotic generation, the MAT gene deletion is related to ascospore dimorphism and mating type switching in S. trifoliorum, and ascospore dimorphism was also observed in S. sclerotiorum. Determining the nature of the dimorphic ascospores and their prevalence in relation to environmental cues could significantly advance our understanding how S. sclerotiorum populations behave in nature