The ovarian and cervical regions of the rat uterus display a different contractile response to serotonin and prostaglandin F2alpha. I. The estrous cycle

In pharmacological studies using isolated tissues, the sensitivity to different agonists may vary depending on the anatomical region. The aim of the present study was to evaluate the in vitro contractile response to serotonin, prostaglandin F2alpha, and oxytocin of the ovarian and the cervical uterine segments isolated from rats in the four different stages of the rat estrous cycle. Non-cumulative curves were recorded for both, the ovarian and the cervical uterine segments. The cervical portion displayed a higher contractile response to serotonin and a lower response to PGF2alpha than the ovarian portion. Oxytocin induced similar responses in both uterine segments. The uterine ovarian segment displayed a similar sensitivity to serotonin in all the estrous cycle stages, whereas in the cervical segment, influenced by estrogens in diestrus and proestrus, an increase in contractility was observed. According to these findings, serotonin might participate in the spermatozoa transport toward the oviduct. The higher response of the ovarian portion to prostaglandin F2alpha is in line with its role during labor and delivery.     

Abundance,population structure and vertical distribution of dominant calanoid copepods on the eastern Weddell Sea shelf during a spring phytoplankton bloom

The main emphasis of this study was to analyse the short-term development of abundance, population structure and vertical distribution of the dominant calanoid copepods during a phytoplankton bloom in the coastal area of the eastern Weddell Sea in December 2003. Microcalanus pygmaeus was by far the most abundant calanoid species. Metridia gerlachei, Ctenocalanus citer, Calanoides acutus, Calanus propinquus and the ice-associated Stephos longipes were also present in considerable proportions. The observed changes in the population characteristics and parameters of these species are described in detail and discussed in the context of the spring phytoplankton bloom. A conspicuous event occurring during the final stage of the study was the development of a strong storm. While the results suggest that this storm did not have any considerable influence on the populations of all other investigated copepod species, it very likely caused pronounced changes in the S. longipes population present in the water column. Before the storm, S. longipes was found primarily in the upper 100 m of the water column, and its population was dominated by adults (mean proportion = 41%) and the copepodite stage I (mean proportion = 30%). After the storm, the abundance increased considerably, and the copepodite stage I contributed by far the largest proportion (53%) of the total population indicating that the early copepodite stages probably had been released from the sea ice into the under ice water layer due to ice break-up and ice melt processes caused by the storm.     

Relationships between Antarctic coastal and deep-sea particle fluxes: implications for the deep-sea benthos

Downward particle fluxes measured by means of sediment traps to a shallow semi-closed bay (Johnson’s Dock, Livingston Island) and to a deep basin in the western Bransfield Strait (Antarctic Peninsula) showed the important role of glaciers as sediment carriers and suppliers to the ocean in a continent without major rivers such as Antarctica. The trap moored in Johnson’s Dock collected coarse sediment (>1 mm mesh) not observed in the offshore traps, which mainly received fine sediment and faecal pellets. The annual total mass flux (TMF) to the coastal zone (15 m) was 900- and three times that to mid-depth (500 m) and near-bottom (1,000 m) traps, respectively. The fine sediment flux was especially important due to its biogenic particle contents. Despite the differences in TMF to the coastal zone and near the bottom in the deep basin, the organic carbon (OC) flux was similar in both environments (16 and 18 g m⁻², respectively), whereas biogenic silica (BSi) flux increased three times with depth (75 and 201 g m⁻², respectively). These fluxes imply that an important part of the particulate organic matter deposited in the coastal zone is advected basinward within the fine-particle flux. Thus, benthos in deep areas depends largely on the lateral transport of biogenic material produced in shallow environments near the coast. It is also proposed that the disintegration of Antarctic ice shelves and the consequent increment of ice calving may produce local devastations of ecological importance not only on the shallow but also on the rich Antarctic deep-sea benthic communities due to an increment of iceberg scouring and reduction of the organic matter supply.     

Monitoring biofouling communities could reduce impacts to mussel aquaculture by allowing synchronisation of husbandry techniques with peaks in settlement

Fouling organisms in bivalve aquaculture cause significant economic losses for the industry. Managing biofouling is typically reactive, and involves time- and labour-intensive removal techniques. Mussel spat settlement and biofouling were documented over 20 months at three mussel farms within Port Phillip Bay (PPB), Australia to determine if knowledge of settlement patterns could assist farmers in avoiding biofouling. Mussel spat settlement was largely confined to a 2-month period at one farm. Of the problematic foulers, Ectopleura crocea settlement varied in space and time at all three farms, whilst Ciona intestinalis and Pomatoceros taeniata were present predominantly at one farm and exhibited more distinct settlement periods. Within PPB, complete avoidance of biofouling is impossible. However, diligent monitoring may help farmers avoid peaks in detrimental biofouling species and allow them to implement removal strategies such as manual cleaning, and postpone grading and re-socking practices, until after these peaks.     

Production of plant protoplasts by enzymes from selected wood-destroying fungi

The goal of this work was to select higher fungi for the production of enzymes able to produce plant protoplasts. The hydrolytic capacity of various species of wood-detsroying fungi was examined to select those with the maximal hydrolytic capacity. The selection criteria included attack on cellulose, and oligo-and polysaccharides by each fungus species. Lenzites elegans, gonoderma applanatum and Pycnoporus sanguineus produced thr richest enzymatic mixtures, which were evaluated for their protoplasting ability. L. elegans has the best enzymatic mixture able to [roduced plant protoplasts with the shortest time for maceration of plant tissues, followed by G. applanatum and P. sanguineus. The potential of these fungi and the simplicity of enzyme proudtcion suggest the possibility of commercial applications.Correepondence to: A. R. Sampietro     

Organic carbon and biogenic silica in marine sediments in the vicinities of the Antarctic Peninsula: spatial patterns across a climatic gradient

To assess whether sea floor sediment reflects the characteristics of the upper water column, organic carbon (OC) and biogenic silica (bSi) were measured in seventeen 5-cm-long sediment cores recovered within a climatic gradient from the northwestern Weddell Sea (WS) to the Drake Passage (DP) across the Bransfield Strait (BS). Climate settings in the study area vary from dry and cold (polar) conditions with seasonal sea ice coverage in the WS to a more humid and warm (oceanic) environment where no seasonal sea ice develops in the DP, with the BS as transitional zone undergoing seasonal sea ice coverage. OC varied between 0.2 and 1.7 % and represented more than 90 % of the total carbon, and bSi varied between 2 and 13 %. The profiles of both variables along the sediment cores suggested that the surface mixed layer is at least 5 cm thick. The inventories of the upper 5 cm of the sediment column were calculated for both variables. Regional averages were significantly lower for OC in DP samples and higher for bSi in the BS. These results suggested relatively high bSi export to the seabed in the BS, higher degradation for OC in the DP and lower bSi export from the euphotic zone in the WS. The observations made evident that the biogenic matter contents in the sediment not necessarily replicate their production characteristics at the upper ocean even across strong climatic gradients. The results may provide a useful baseline for paleo-reconstructions in a rapidly changing environment.     

Breeding status influences timing but not duration of moult in the Northern Fulmar Fulmarus glacialis

Seabirds are key marine top predator species that are often used as indicators of the environmental quality of the oceans. Their breeding phenology has been studied extensively, but their pelagic habits mean less is known about the phenology of other events during the non-breeding period. Here, we used miniaturized saltwater immersion light-based geolocators (GLS) to investigate moult phenology in individuals with known breeding histories in a population of Northern Fulmar Fulmarus glacialis in Orkney, Scotland. As seabirds spend more time on the water during moult, moulting periods can be identified from patterns of variation in the amount of time that birds are in contact with saltwater. Estimates of daily variation in this behaviour during the non-breeding period were based upon wet/dry sensors and then modelled to characterize the timing of the moult. Light-based geolocation provided information on the areas used by each individual during its moult period. Inter-individual variability in moult timing was investigated in relation to sex and breeding success in the previous summer. We found a sex difference in the location of the moult, but not in its timing. However, the timing of moult did differ between individuals that had succeeded or failed in their previous breeding attempt, with successful breeders moulting the latest. In contrast, the duration of moult did not depend on prior reproductive success, but there was evidence of inter-annual variation in moult duration. GLS studies have provided a step change in our understanding of the at-sea distribution of pelagic seabirds. Our work highlights how activity data from these devices can add value to such studies by identifying key phases of the annual cycle, and locations at these times, when seabirds may be at particular risk. Furthermore, our findings indicate that individual and inter-annual variation in breeding success may influence phenological patterns in other phases of the Northern Fulmar annual cycle.     

Long term culture of mesenchymal stem cells in hypoxia promotes a genetic program maintaining their undifferentiated and multipotent status

Background  

In the bone marrow, hematopietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multipotency. However, whereas most studies addressed the effect of transient in vitro exposure of MSC to hypoxia, permanent culture under hypoxia should reflect the better physiological conditions.