Percorrer por autor "Pasupuleti, Rajeev"
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- Can zooplankton biodiversity be used to evaluate trophic state and water quality of a mountain reservoir?Publication . Geraldes, Ana Maria; Pasupuleti, Rajeev; Alonso, MiguelZooplanktons are a keystone in the ecosystem functions transferring energy to higher trophic levels. Moreover, zooplankton community is susceptible to quick responses with changes in the environment. Therefore, this community can be regarded as a valuable indicator of ecological integrity and water quality. Serra Serrada is a mountain meso‐eutrophic reservoir (latitude: 41º57'12''N; longitude: 6º 46' 44''W; altitude 1300 m) in Portugal, which is prone to water level fluctuations. Despite of being an artificial lake, zooplankton showed high biodiversity including 13 taxa of Rotifera, 12 taxa of Cladocera and 3 of Copepoda. Some of these species, such as Ceriodaphnia quadrangula, Drepanothrix dentate and Holopedium gibberum are classified as rare in the context of Iberian Peninsula. In order to assess the role of zooplankton community composition as environmental indicator, the present research aimed to compare the values obtained for Carlson's Trophic State Index (TSI) (based on total phosphorous concentration (TP), water transparency (SD) and chlorophyll ‘a' concentration) to the obtained zooplankton metrics like: (1) The trophic state index of rotifer abundance (TSI N rot); (2) the ratio of crustacean abundance to rotifer abundance and (3) the ratio of large (>10 μg) cladoceran abundance to total cladoceran group abundance. All the components of TSI increased during the low level phase. Although, rotifer being dominant in all phases (except in the emptying phase, where Copepoda was dominant), TSI N rot increased in the low level phase, when TP and Chl a concentrations increased and SD decreased. Crustacean/Rotifer ratio also followed the same pattern, showing the lowest value in the low level phase. Results for large Cladocera/total Cladocera ratio were not so elucidative. Therefore, zooplankton metrics were in line with TSI, confirming that zooplankton community can be a good indicator of reservoir water quality and of ecological integrity.
- Comunidades zooplanctónicas: uma ferramenta valiosa na gestão holística das bacias hidrográficas?Publication . Crispim, Maria Cristina; Pasupuleti, Rajeev; Geraldes, Ana MariaOs efeitos das ações antropogénicas nos cursos superiores das bacias hidrográficas (ecossistemas dulçaquícolas) refletem-se de forma intensa nos ambientes costeiros. Assim, o desenvolvimento de ferramentas de monitorização da integridade ecológica dos ecossistemas dulçaquícolas é crucial para a boa gestão de toda a bacia hidrográfica. As comunidades zooplanctónicas têm respostas rápidas às perturbações e mudanças ambientais, mas ao mesmo tempo menos instantâneas que os parâmetros físicos e químicos e, por isso, são relevantes como bioindicadores, podendo ser uma ferramenta valiosa na gestão das bacias hidrográficas. O presente trabalho decorreu em dois reservatórios portugueses: Serra Serrada localizado na Bacia do Rio Douro (latitude: 41º57’12’’N; longitude: 6º 46’ 44’’) e Aguieira localizado na Bacia do Rio Mondego (latitude 40° 20' 26.60" N; longitude 8° 11' 48.15" W). O objectivo principal do presente trabalho é avaliar se alguns índices bióticos, baseados em comunidades zooplanctónicas, desenvolvidos para avaliarem a qualidade e a integridade ecológica de lagos e reservatórios da Europa Central, mantêm a sua adequabilidade quando aplicados em ecossistemas aquáticos de caracter mediterrânico. Assim, em ambos os reservatórios, foi analisada a composição e variação da estrutura das comunidades zooplanctónicas, identificados os principais factores ambientais que as influenciam e comparados vários índices bióticos (razão entre a abundância de crustáceos e rotíferos (NCrust/NRot), razão entre a abundância de cladóceros de grande dimensão e o total de cladóceros presentes na comunidade (NLarge-Clad/NClad) e o índice do estado trófico baseado na abundância de rotíferos). Posteriormente, os resultados obtidos para estes índices foram comparados com os resultados obtidos para o índice trófico de Carlson que apenas considera variáveis de natureza ambiental e físico-química. O ciclo hidrológico de Serra Serrada caracteriza-se por possuir 3 fases: uma em que o nível da água é máximo, fase de nível mínimo e uma fase de reenchimento. O reservatório da Aguieira possui também flutuações acentuadas no nível da água e, no verão, ocorrem blooms de cianobactérias. Em ambos os reservatórios, verificou-se que os factores ambientais que mais influenciavam as comunidades zooplanctónicas eram a temperatura, as concentrações de nutrientes (fósforo e azoto) e clorofila a e a transparência da água. A razão NCrust/NRot e o índice trófico baseado na abundância dos rotíferos apresentaram valores mais elevados na fase de nível mínimo (Serra Serrada) e quando ocorriam blooms de cianobactérias (Aguieira). Estes valores foram coincidentes com os valores máximos do índice trófico de Carlson. Este facto indica que estes índices são apropriados para serem utilizados na gestão de massas de água interiores também em climas mediterrâneos, podendo ser olhados como ferramentas para avaliar e detectar de forma rápida perturbações ambientais que possam colocar em causa a integridade ecológica destes ecossistemas e, em última instância, de toda a bacia hidrográfica, incluindo os ecossistemas costeiros.
- Functionalization of spider silk using enzymatic sortase A couplingPublication . Pasupuleti, Rajeev; Hedhammar, My; Jansson, Ronnie; Dias, TeresaSilk is a natural protein fibre spun by spiders, some insects and silkworms. Spider silk is of interest because of its mechanical strength, elasticity and biocompatibility, in fact, spider silk is considered to be the strongest natural biopolymer known. Recombinant production of spider silk proteins has begun to meet the needs of the growing biotechnological interests, and recombinant production in various hosts has been a widely used approach, with varying results. In search of mimicking the silk proteins, 4RepCT has been engineered with only 4 gly/ala repeats followed by a non-repetitive C-terminal. This protein has been successfully produced in a soluble form using Escherichia coli, yet forming macroscopic silk-like fibres. Studies on 4RepCT fibres have shown biocompatibility and a limited immunological response when subcutaneously implanted in rats. Functionalization is a process where additional peptide motifs, protein domains or organic compounds are coupled to 4RepCT to add new properties for use in medical and biotechnology disciplines. There is, however, currently, a need for new coupling methods, in addition to, for example, manipulation on the genetic level. Therefore, this study was aimed to investigate a new method for functionalization of 4RepCT silk using two model proteins (domain Z and fibroblast growth factor-2) with the help of Sortase A mediated covalent coupling. The results have shown that a Sortase A enzyme with 3 mutations, coupling at ambient temperature and a reaction time between 0.5 and 1.5 h are suitable conditions for efficient coupling of the model proteins to 4RepCT silk coatings. Coupling of the Z domain to silk using the Coupling during coating (CDC) method and FGF2 to silk using the Coupling after coating (CAC) method showed best binding of their target molecules (IgG and FGF2 receptor, respectively). Analysis by Surface Plasmon Resonance was efficient to distinguish these differences in binding rates.
- Influence of Some Environmental Variables on the Zooplankton Community of Aguieira Reservoir (Iberian Peninsula, Portugal): Spatial and Temporal TrendsPublication . Geraldes, Ana Maria; Pasupuleti, Rajeev; Silva-Santos, PedroThis research was aimed to assess the spatial and temporal trends in the zooplankton community of Aguieira reservoir at the Mondego catchment (Iberian Peninsula, Portugal) in response to some environmental variables. A total of 24 zooplankton as well as water samples were collected in the months of March (spring), May (early summer), September (late summer) and December (winter) of 2010 and 2011. The data from these samples was obtained by the Descriptive (range, percentage) and multivariate statistics (Non-metric Dimensional Scaling (n-MDS), Bray-Curtis distance, Canonical Correspondence Analysis (CCA). Altogether twenty-three zooplankton species were recorded which included Rotifera (12), Cladocera (8) and Copepoda (3). In terms of abundance, Rotifera (Keratella spp. and Polyarthra sp.) dominated in May and September, while Copepoda (Copidodiaptomus numidicus and Tropocyclops prasinus) overtook in December and March. Cladocera was the least abundant taxon of which Daphnia longispina and Bosmina coregoni has shown abundance from December-March whereas Chydorus sphaericus, Ceriodaphnia pulchella and Diaphanosoma brachyurum from May-September. Results of n-MDS exhibited similar spatial and inter-annual patterns with environmental variables and zooplankton community. However, there were differences between the samples collected in the months of March/December and May/September in both the years. Results of CCA revealed water temperature and algal biomass as the main environmental gradients that influenced the zooplankton community. Since some of the observed changes in the zooplankton composition might be influenced by other complex abiotic/biotic interactions. Therefore this study suggests further research to understand the complexity of the interactions between biological, environmental and climatic parameters of the reservoir. Neverthless, understanding the dynamics and nature of zooplankton communities is crucial for the implementation of good management practices for reservoirs.
- Zooplankton community structure in a deep reservoir: seasonal trends and structuring variables?Publication . Geraldes, Ana Maria; Silva-Santos, Pedro; Pasupuleti, RajeevThis research aimed at monitoring and characterizing the zooplankton community of Aguieira reservoir (40.33 N; 8.19 W). Aguieira trophic state, nutrient concentration (the highest amounts were observed in summer) and ultimately water quality can be explained by the internal disturbance induced by the intense water level fluctuations. This indeed leads to an increase in suspended particulate material in the water column. Besides, the exposure of littoral sediments to cycles of drying and wetting also increases nutrient availability, preventing macrophytes establishment. These phenomena with the input of allochthonous nutrients originated from human activities in the catchment area lead to the increase of phytoplankton biomass (mainly Cyanobacteria) during summer. When Cyanobacteria were dominating the phytoplankton assemblage, zooplankton community was clearly dominated by the rotifer, Keratella cochlearis and by the caldoceran, Chydorus sphaericus. In the absence of Cyanobacteria, Copidodiaptomus numidicus and Daphnia longispina subsisted as the most representative species. Canonical correspondence analysis (CCA) identified two main environmental gradients that shape zooplankton community: one being temporal mainly related to temperature, and the other, a trophic gradient associated to chlorophyll a concentration, water transparency, nitrates and nitrites. Variance partitioning using CCA revealed that the largest portion (45%) of the total variation explained (70%) was attributed to the interaction between lake and environmental variables.
- Zooplankton: a valuable environmental indicator tool in reservoir ecology management?Publication . Geraldes, Ana Maria; Pasupuleti, RajeevThe trends in zooplankton community were assessed in response to the variations in the trophic state and water quality, in Serra Serrada, a shallow reservoir, with seasonal water level fluctuations, located in the Portuguese part of River Douro Basin. Various ratios were also calculated: (1) the ratio of crustacean abundance to rotifer abundance (NCrust/NRot); (2) the ratio of large (>10 μg) cladoceran abundance to total cladoceran group abundance (NLarge- Clad/NClad); (3) The trophic state indices of rotifer abundance. The reservoir’s hydrological cycle was characterized by three phases. The maximum level phase lasted from January to the beginning of June, the emptying phase from mid-June to the beginning of September and the minimum level phase between mid-September to the beginning of the first autumn/winter rain events. The highest values for total phosphorus, soluble reactive phosphorus, nitrate, and ‘chlorophyll a’ were found during the minimum level phase. Rotifera was the most abundant taxa, except in summer and in autumn where Cladocera and Copepoda were dominant. The ordination space defined by the first two RDA axis accounted for 84.2% of species–environment relations and represented 25.4% of the variation in species data. The ratio NCrust/NRot have shown the highest role of rotifers in the zooplankton community in the low level phase. The ratio NLargeClad/NClad displayed a decreasing trend in the abundance of large-sized cladocerans for the same mentioned period. Redundancy analysis (RDA) revealed a strong influence of temperature, chlorophyll a, soluble reactive phosphorous and total phosphorous to the observed significant associations between the zooplankton assemblage and environmental variables. Therefore, these indices are suitable to be used in reservoir management as rapid tools to evaluate the effects of environmental disturbances with a concern to the reservoir ecological integrity.
- Zooplankton: a valuable environmental indicator tool in reservoir ecology management?Publication . Geraldes, Ana Maria; Pasupuleti, RajeevThe trends in zooplankton community were assessed in response to variations in the trophic state and water quality, occurring in a shallow reservoir subjected to seasonal water level fluctuations. Concomitantly, various ratios were calculated: (1) the ratio of crustacean abundance to rotifer abundance (NCrust/NRot); (2) the ratio of large (>10 μg) cladoceran abundance to total cladoceran group abundance (NLarge-Clad/NClad); (3) The trophic state indices of rotifer abundance. The reservoir’s hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid-June to the beginning of September and the minimum level phase lasted from mid-September to the beginning of the first autumn/winter rain events. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, and ‘chlorophyll a’ were found during the minimum level phase. Rotifera was the most abundant taxa, except in summer and in autumn where Cladocera and Copepoda were dominant. Redundancy analysis (RDA) revealed a strong contribution of temperature, chlorophyll a, soluble reactive phosphorous and total phosphorous to the observed significant associations between the zooplankton assemblage and environmental variables. The ordination space defined by the first two RDA axes accounted for 84.2% of species–environment relations and represented 25.4% of the variation in species data. The ratio NCrust/NRot showed the higher role of rotifers in the zooplankton community in the low level phase; the ratio NLargeClad/NClad showed a decreasing trend in the abundance of largesized cladocerans for the same mentioned period. Therefore, these indices seem suitable to be used in reservoir management as rapid tools to evaluate the effects of environmental disturbances to reservoir ecological integrity.