273 research outputs found
Life history and temporal distribution of Orchestia sp. cf. cavimana (Amphipoda, Talitridae) on a lake shore in central Italy
No full textThe life history of the amphipod Orchestia sp. cf. cavimana (Heller, 1865) was studied throughout the course of a year with monthly samplings and the use of pitfall traps along the shores of Lake Albano in central Italy. The data thus obtained showed two peaks in abundance (the first in June and the second in October) and a minimum capture frequency in February. Egg-bearing females were recorded in spring and late summer, whilst recruitment occurred from spring to autumn, with maximum in June and October. The data collected also indicated the presence of a positive correlation between the abundance of talitrids and both temperature and sediment moisture. Morphological analysis enabled the identification of four different cohorts (with a lifespan of the species of approximately 12-15 months) all four of which remained distinguishable throughout the course of the year. It, moreover, enabled sex determination in individuals of 5 or more millimetres. The subsequent distribution indicated that, when significant, the sex ratio was female biased and that maximum size was greater in males. In particular, maximum sizes were recorded in spring for both males and females and were of 17.5 and 13.0 mm, respectively. Furthermore, the total body length recorded for egg-bearing females was positively correlated with the number of eggs in their brood pouch. (C) 2009 Elsevier GmbH. All rights reserved
Life history of the talitrid amphipod Macarorchestia remyi (Schellenberg, 1950) on a Tyrrhenian sandy beach, Italy
No full textIn this study, we analysed the life cycle and some aspects of the reproductive biology of the talitrid amphipod Macarorchestia remyi (Schellenberg, 1950) on a sandy beach in central Italy (Tyrrhenian Sea). The species is strongly associated with rotting wood carried by the sea. The animals were sampled once a month by hand over 1 year (May 2006-April 2007) and a total of 3,484 individuals were collected. Results showed the occurrence of intersexes in addition to males and females (n = 268) and a sex ratio always in favour of females. Breeding peaked twice during the year and the number of eggs in the ventral brood chamber ranged from 3 to 19. Linear regression analysis showed a positive correlation between total length of ovigerous females and the number of eggs they carried. The mean length of both mature males and mature females was 6 mm, while the maximum length was 13 mm. The presence of two cohorts during the year was also identified. Our results suggest that, despite the ephemeral habitats where the species lives, the population is stable over time and its life cycle does not differ in relation to other talitrid species that live on beaches
Supralittoral amphipod abundances across habitats on Mediterranean temperate beaches
No full textCommunity complexity and abiotic conditions are key components of environmental heterogeneity that affect the abundance and distribution of species. In this study we evaluated how environmental conditions affect abundances of supralittoral amphipods (Talitridae) in four habitats (sandy beach, rivermouth, wrack and lakeshore), along the Italian peninsula in the Mediterranean Sea. All samplings covered a 12 month period, and used the same sampling methodology thereby enabling comparison of abundances and species composition and richness. Four species (Talitrus saltator (Montagu, 1808), Orchestia gammarellus (Pallas, 1766), O. montagui Audouin 1826, O. cf. cavimana Heller 1865) were collected in the different habitats, but most species were found or were abundant in only one of the four habitats. Abundances of talitrids (numbers per sampling hour) differed significantly among the habitats with highest abundances found in the wrack and on the riverbank in proximity to an estuary, and lowest abundances observed on four sandy beach sites. Environmental conditions (temperature, moisture, substrate penetrability) differed among the habitats and were associated with some of the among-site variability in abundances. Our findings demonstrate that talitrids thrive better in some supralittoral habitats than others, and that some habitats could be considered to be "hotspots" of talitrid ecology and biodiversity.Community complexity and abiotic conditions are key components of environmental heterogeneity that affect the abundance and distribution of species. In this study we evaluated how environmental conditions affect abundances of supralittoral amphipods (Talitridae) in four habitats (sandy beach, rivermouth, wrack and lakeshore), along the Italian peninsula in the Mediterranean Sea. All samplings covered a 12 month period, and used the same sampling methodology thereby enabling comparison of abundances and species composition and richness. Four species (Talitrus saltator (Montagu, 1808), Orchestia gammarellus (Pallas, 1766), O. montagui Audouin 1826, O. cf. cavimana Heller 1865) were collected in the different habitats, but most species were found or were abundant in only one of the four habitats. Abundances of talitrids (numbers per sampling hour) differed significantly among the habitats with highest abundances found in the wrack and on the riverbank in proximity to an estuary, and lowe
Genotoxicity biomarkers in the amphipod Gammarus elvirae exposed in vivo to mercury and lead and basal levels of DNA damage in two cell types
No full textThe present work deals with the application of genotoxicity biomarkers by means of the Comet assay in haemocytes and spermatozoa of the crustacean Gammarus elvirae exposed in vivo to heavy metals. Furthermore, a basal levels (BLs) study of DNA damage in the two cell types considered for two different gammarids species, G. elvirae and Echinogammarus veneris, was carried out. It is important to identify factors that influence the outcome of the assay in order to obtain reliable and reproducible results usable for risk assessment purposes. Our results highlight that the Italian legal limits for Hg and Pb, respectively, 0.5 and 50 μg/L, are inadequate for establishing safety thresholds in the aquatic environment. Furthermore, the freshwater invertebrate G. elvirae, used for the first time to measure the effect of genotoxicants, is a good candidate for evaluating the genotoxicity damage induced by heavy metals. Our results concerning spermatozoa show excessively variable responses and high BLs
Effects of hypercapnia on peripheral vascular reactivity in elderly patients with acute exacerbation of chronic obstructive pulmonary disease
No full textBlood acid-base imbalance has important effects on vascular reactivity, which can be related to nitric oxide (NO) concentration and increased during hypercapnia. Release of NO seems to be linked to H+ and CO2 concentration and to exacerbation of chronic obstructive pulmonary disease (COPD), a common medical condition in the elderly. Flow-mediated dilation (FMD), a valuable cardiovascular risk indicator, allows assessment of endothelial-dependent vasodilation, which is to a certain extent mediated by NO. We investigated the effects of hypercapnia and acid-base imbalance on endothelial-dependent vasodilation by measurement of FMD in 96 elderly patients with acute exacerbation of COPD. Patients underwent complete arterial blood gas analysis and FMD measurement before (phase 1) and after (phase 2) standard therapy for acute exacerbation of COPD and recovery. Significant differences between phase 1 and phase 2 were observed in the mean values of pH (7.38±0.03 versus 7.40±0.02, P<0.001), pO2 (59.6±4.9 mmHg versus 59.7±3.6 mmHg, P<0.001), pCO2 (59.3±8.63 mmHg versus 46.7±5.82 mmHg, P<0.001), FMD (10.0%±2.8% versus 8.28%±2.01%, P<0.001) and blood flow rate (1.5±0.3 m/s versus 1.5±0.3 m/s, P=0.001). FMD values were positively correlated with pCO2 values (r=0.294, P=0.004) at baseline. A significant correlation was also found between relative changes in FMD and pCO2 levels, passing from phase 1 to phase 2 (r = 0.23, P=0.023). Patients with higher baseline endothelium-dependent vasodilation as evaluated by FMD showed greater modification with regard to pCO2 changes (2.6±1.39 versus 1.59±1.4, P=0.012). In conclusion, endothelium-dependent vasodilation as evaluated by FMD was elevated during hypercapnia, and varied significantly according to pCO2 changes in patients with higher baseline levels, suggesting that vascular reactivity in acute COPD exacerbations in the elderly depends on integrity of the vascular endothelium. © 2014 de Matthaeis et al
ALLOZYMES AND mtDNA REVEAL TWO DIVERGENT LINEAGES IN ORCHESTIA CAVIMANA (AMPHIPODA: TALITRIDAE)
No full textWe report on allozyme and mitochondrial DNA variation in 13 populations of the supralittoral amphipod Orchestia cavimana. The species colonizes fresh and brackish shores of Northern Africa, Near East and throughout Europe. Populations were sampled across a large part of the species range (Cyprus, Turkey, northern and southern Italy, United Kingdom and Germany), including the type locality (Cyprus). Both sets of molecular markers agree in identifying two divergent lineages. A first lineage includes populations from Cyprus and Turkey. A second genetically homogeneous lineage groups Italian, English and German populations. Genetic divergence between the two lineages is high (D-Nei = 0.720 +/- 0.06 for allozymes and K2P = 0.191 +/- 0.001 for mitochondrial DNA) and comparable to that among morphologically distinct congeneric species reported for the same set of molecular markers
Temporal and spatial distribution of three supralittoral amphipod species on a sandy beach of central Italy
No full textThe distribution of three talitrid species-Talitrus saltator (Montagu, 1808), Orchestia gammarella (Pallas, 1766), Platorchestia platensis (Kroyer, 1845)-in the beach-dune system at the mouth of the Mignone River (central Italy) was analysed. It was related to the variations of the following abiotic factors: temperature, penetrability, pH, conductivity and moisture of the sediment. The beach-dune system is influenced by human impact and natural erosion. All species showed a maximum capture frequency in November, while the abundance decreased to a minimum in July. T. saltator was dominant on the beach, the other two along the riverbank. Juveniles were abundant along the riverbank; they were most abundant in November and almost disappeared in summer. T. saltator was more abundant near the waterline during the hottest months and occupied the inner beach in winter, with occasional presences on the dune. Regression analysis between the abiotic factors and species abundance showed a positive relationship with pH and temperature for T. saltator, while O. gammarella was negatively related to pH. Canonical correspondence analysis (CCA) showed that penetrability, moisture and temperature had the greatest influence on the species. T. saltator was almost entirely confined to the beach transects and strongly associated with penetrability, temperature and pH values. O. gammarella was mostly associated with the riverbank and P. platensis only found there and on a nearby pool. The two species were mainly influenced by moisture and variations in grain sizes of the sediment. © 2007 Springer-Verlag
Pattern of gene flow and genetic divergence in the three Italian species of the cave cricket genus Troglophilus (Orthoptera, Rhaphidophoridae): allozyme data
No full textIn this paper, we report data on the levels of genetic differentiation among and gene flow within each of the three species of the cave cricket genus Troglophilus living in Italy. We analyzed genetic variation at 18 enzymatic loci in 12 populations of T. cavicola, 6 populations of T. neglectus and 3 populations of T. andreinii. In particular, populations of T. cavicola and T. neglectus were sampled in overlapping geographical areas, from North-Eastern Italy to Slovenia and Croatia. We found a significant isolation by distance pattern for T. cavicola, indicating that the spatial distribution of genetic heterogeneity is best described by a stepping-stone model. The same does not hold for T. neglectus. Within the three species, the pattern of genetic structuring was mainly related to the limestone structure of the area rather than the availability of epigean routes for dispersal. A calibration for gene flow estimates in cave crickets is provided to discriminate between and current gene flow. This supports previous cave cricket data suggesting that detected gene flow is due to historical rather than current connections among populations
Exploratory analysis of talitrid population genetics as an indicator of the quality of sandy beaches
No full textAllozymic variation was studied at 23 loci in 10 populations of Talitrus saltator, two populations of Talorchestia deshayesii and two populations of Talorchestia brito from the Mediterranean and Baltic Seas. Levels of genetic differentiation among the three species showed a close relationship between T. saltator and T. deshayesii, whereas T. brito was more genetically differentiated. Within T. saltator, it was possible to recognise two main clusters, the first grouping consisting of Baltic, Tyrrhenian and North African populations, the second comprising Adriatic and East Mediterranean populations. Talitrus saltator populations were generally characterised by low levels of gene flow (Nm < 1). The relationship between Nm and geographic distances was analysed to test for an isolation by distance pattern in the spatial genetic variation. Isolation by distance was detected at the scale of the whole Mediterranean, with geographic distance explaining about 50% of the variance in gene flow. The North African populations showed an island model of genetic structuring; this result is mainly due to the anomalous genetic pattern of a population from a Tunisian beach (Tabarka) highly exploited for tourism. Human activities, which may influence T. saltator population dynamics, are believed to be responsible for the observed pattern of genetic variation in North Africa
Distribuzione della composizione corporea in soggetti anziani affetti da sindrome metabolica. Distribution of body composition in the elderly with metabolic syndrome.
No full text- …
