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Corynosoma australe and C. cetaceum are the most frequently reported acanthocephalans in fish from the Argentine Sea, particularly in central and northern areas. Their definitive hosts are otariids and odontocete cetaceans, respec...
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Corynosoma australe and C. cetaceum are the most frequently reported acanthocephalans in fish from the Argentine Sea, particularly in central and northern areas. Their definitive hosts are otariids and odontocete cetaceans, respectively. The low specificity of these larvae, in combination with high infective capability and long survival periods in fish, make them potentially good biological markers for stocks and other biological features of their fish hosts. In order to determine the distribution patterns of these species and their determining factors, a large dataset composed by newly collected fish samples, published and unpublished data from previous studies by the authors in the region were analysed in relation to host and environmental variables. The complete dataset comprised a total of 5084 fish, belonging to 29 species distributed in 21 families and 9 orders. Host size and trophic habits arose as the main determinants of abundance for both species of Corynosoma, showing higher abundances on larger fish and on higher trophic levels, as it is usual for trophically transmitted parasites. Biogeographic province and depth (indirectly representing the temperature of water) were the main drivers of the spatial distribution, displaying a latitudinal pattern associated to the temperature clines created by the interaction of Malvinas and Brazil currents, determining a decrease in abundance southwards and towards the deeper areas. No patterns were found regarding the distribution of definitive hosts. The knowledge of these distribution patterns of Corynosoma spp. in fish at regional scale, as well as of their causes, provides useful information to design management and conservation policies thus contributing to maintain the full and sustainable productivity of fisheries.
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Vitamins are vital for normal growth and survival of living organisms and they are distributed in feedstuffs in small quantities. This review is focused on the liposoluble vitamins (A, D, E and K) in the diets and metabolic respon...
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Vitamins are vital for normal growth and survival of living organisms and they are distributed in feedstuffs in small quantities. This review is focused on the liposoluble vitamins (A, D, E and K) in the diets and metabolic responses of the Argentine penaeoid shrimps Pleoticus muelleri and Artemesia longinaris, distributed along the South American coast line. Growth, survival and histological analyses serve as indicators of the nutritional value derived from vitamin deficiency. Liposoluble vitamins are also related to stress, antioxidant defense and immune response of shrimps. Effective diet for shrimp culture that provide not only macronutrients including protein and lipid but also micronutrients such as vitamins for optimal growth is an ever improving subject. This review may help formulating suitable feeds for shrimps.
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The ascomycete plant pathogen Botrytis cinerea secretes aspartic proteinase (AP) activity. Functional analysis was carried out on five aspartic proteinase genes (Bcapl-5) reported previously. Single and double mutants lacking thes...
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The ascomycete plant pathogen Botrytis cinerea secretes aspartic proteinase (AP) activity. Functional analysis was carried out on five aspartic proteinase genes (Bcapl-5) reported previously. Single and double mutants lacking these five genes showed neither a reduced secreted proteolytic activity, nor a reduction in virulence and they showed no alteration in sensitivity to antifungal proteins purified from grape juice. Scrutiny of the B. cinerea genome revealed the presence of nine additional Bcap genes, denoted Bcap6-14. The product of the Bcap8 gene was found to constitute up to 23% of the total protein secreted by B. cinerea. Bcap8-deficient mutants secreted similar to 70% less AP activity but were just as virulent as the wild-type strain. Phylogenetic analysis showed that Bcap8 has orthologs in many basidiomycetes but only few ascomycetes including the biocontrol fungus Trichoderma harzanium. Potential functions of the 14 APs in B. cinerea are discussed based on their sequence characteristics, phylogeny and predicted localization.
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Polymorphid acanthocephalans are parasites of marine mammals, waterfowl and ichthyophagous birds. Among these, the genusProfilicollisis known to use exclusively decapods as intermediate hosts. Here, we report the first record of l...
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Polymorphid acanthocephalans are parasites of marine mammals, waterfowl and ichthyophagous birds. Among these, the genusProfilicollisis known to use exclusively decapods as intermediate hosts. Here, we report the first record of living cystacanths ofProfilicollisparasitizing the body cavity of a fish host,Oligosarcus jenynsii,inhabiting the freshwater section of an estuarial system, Mar Chiquita coastal lagoon, in south-east Buenos Aires Province, Argentina. In this environment, cystacanths ofProfilicollis chasmagnathihave been previously recorded infecting decapod crabs and as transient accidental infections in the gut of some carcinophagous fishes. In the present study, larvae from the crabNeohelice granulata, from the intestine of the estuarine fishOdontesthes argentinensisand from the body cavity ofO. jenynsiiwere morphologically and genetically compared, confirming their identity asP. chasmagnathi, a species characteristic of estuaries and marine coasts along Argentina, Uruguay and Chile. These findings can be interpreted as a possible case of incipient paratenicity forProfilicollis, and a colonization event of freshwater habitats, probably promoted by the highly variable conditions, typical of ecotonal environments. In addition, cystacanths of the genusPolymorphuswere also found inO. jenynsii, representing the first record of this genus inOligosarcusfrom Argentina.
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Diverse factors may limit nest-site selection; however, nest predation has long been considered a main factor driving nest-site selection in birds. Marsh-nesting birds face a particularly important trade-off between habitat featur...
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Diverse factors may limit nest-site selection; however, nest predation has long been considered a main factor driving nest-site selection in birds. Marsh-nesting birds face a particularly important trade-off between habitat features that impede their vision of the approach of potential predators and nest concealment from predators. Here, we analyse how different ecological variables influence nest-site selection in the habitat-specialist Wren-like Rushbird (Phleocryptes melanops) breeding in three different wetlands of the Pampas region of Argentina over 3 years. Rushbirds selected nest sites with higher heights and denser vegetation, compared to random sites. Nest height was positively associated with vegetation height and lower visibility from the point of view of aerial predators, and the nest entrance was oriented towards the region with greatest visibility of the nest from the point of view of Rushbirds. Rushbirds seem to flexibly adjust their nest location in response to high predation risk, building their nests under structures built by other birds when breeding colonies of herons and gulls (potential nest predators) are present. Initial nest-site selection is performed by males, which then attempt to attract females to a rudimentary nest. Females sometimes reject such sites and the male then selects a new nesting location. Our study highlights the potential for flexible sex differences in nest-site selection.
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The aim of this study was to analyze pollen from the outer parts of camelid coprolites and contemporaneous sediments to evaluate the potential of coprolites for the reconstruction of the vegetation history of Patagonia during the ...
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The aim of this study was to analyze pollen from the outer parts of camelid coprolites and contemporaneous sediments to evaluate the potential of coprolites for the reconstruction of the vegetation history of Patagonia during the Holocene. The pollen composition of camelid coprolites coming from archeological layers between 10,920 yrs. cal BP and 2823 yrs. cal BP found in the sites Cerro Casa de Piedra 5 and 7 (Perito Moreno National Park, Santa Cruz, Argentina) were analyzed. Coprolites were divided into outer and inner subsamples. Outer subsample pollen extraction was performed through acetolysis and determination and counting under optical microscope. Morisita-Horn index and Wilcoxon test were performed to evaluate similarities between pollen spectra of outer subsamples of coprolites and contemporaneous sediments. The dominant pollen types were: Nothofagus (Nothofagaceae), Empetrum (Ericaceae), Asteraceae subf. Asteroideae, Nassauvia (Asteraceae subf. Mutisioideae), Poaceae and Caryophyllaceae. The similarities found between outer subsamples of coprolites and contemporaneous sediments reflected the dominant pollen types of the vegetation and forest development, whereas significant differences could be attributed to coprolite pollen spectra that may be biased by season of coprolite deposition, selectivity of the diet and/or higher temporal resolution. Also, the presence of pollen types in outer subsamples of coprolites absent in sediments could give information for paleoenvironmental reconstructions by enriching information of the past flora. This study demonstrates that coprolites can be a valuable tool for paleoenvironmental reconstructions in arid and semiarid areas where depositional environments that support pollen preservation are typically rare.
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Crab guarding behaviors are influenced by the biological and physical characteristics that each population experiences in a particular habitat. We studied post-copulatory guarding behavior and the factors affecting it, such as the...
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Crab guarding behaviors are influenced by the biological and physical characteristics that each population experiences in a particular habitat. We studied post-copulatory guarding behavior and the factors affecting it, such as the presence of burrows, female receptivity duration, operational sex ratio (OSR) and male size, in two different populations of Neohelice granulata: Mar Chiquita coastal lagoon (MCL) and San Antonio Oeste (SAO). Laboratory experiments showed that post-copulatory guarding duration varied between the study areas. In MCL, it depended upon the presence of burrows and female receptivity duration, whereas it was independent of the OSR and male size. In SAO, it was dependent upon the OSR and female receptivity duration, whereas it was independent of the presence of burrows and male size. Thus, N. granulata males display different reproductive strategies related to their post-copulatory guarding behavior pattern in different habitats. These strategies are related to the fact that this species constructs and defends a burrow that provides shelter and a place to mate, something that other varunids do not have.
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Nitric oxide (NO) is an essential signal molecule to maintain cellular homeostasis in uni and pluricellular organisms. Conceptually, NO intervenes as much in sustaining basal metabolic processes, as in firing cellular responses to...
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Nitric oxide (NO) is an essential signal molecule to maintain cellular homeostasis in uni and pluricellular organisms. Conceptually, NO intervenes as much in sustaining basal metabolic processes, as in firing cellular responses to changes in internal and external conditions, and also in guiding the return to basal conditions. Behind these unusual capabilities of NO is the chemistry of this molecule, an unstable, reactive, free radical and short half-life gas. It is a lipophilic molecule that crosses all the barriers that biological membranes can impose.
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In the South-western Atlantic, studies dealing with the impacts of debris on marine species are focused mainly on vertebrates, being scarce the studies conducted to determine the association of fouling species to marine debris. A ...
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In the South-western Atlantic, studies dealing with the impacts of debris on marine species are focused mainly on vertebrates, being scarce the studies conducted to determine the association of fouling species to marine debris. A total of 33 marine debris items with fouling specimens were collected in Mar Chiquita coastal lagoon, Argentina. Species richness varied between one and five species per debris item, and dominant species included the barnacle Amphibalanus improvisus (93.94%), followed by the bryozoan Membranipora sp. (72.73%), undetermined polychaetes (36.36%), the mollusc Ostrea sp. (15.15%), the hydrozoan Amphisbetia operculata and the mollusc Brachidontes rodriguezii (3.45%, in both cases). We concluded that marine debris constitutes a suitable settlement site for sessile species inhabiting the lagoon, where hard-substratum are absent; while buoyancy analysis suggested that the initial colonization occurred both on marine debris suspended in the water column or at the sea surface, and in those laying on the seafloor.
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