Links between the structure of an Antarctic shallow-water community and ice-scour frequency

Ice is a major structuring force in marine and freshwater environments at high latitudes. Although recovery from scouring has been quantified in time, the frequency of scouring in the Antarctic has not. We placed grids of markers at 9–17 m depth at two sites, to study ice-scouring over 2 years at Adelaide island (Antarctic Peninsula). We quantified the time scale of scour frequencies, and linked this to community mortality, age and diversity. Markers were hit from zero to at least three times in 2 years. At the least disturbed site (South Cove) 24% of markers were destroyed per year, whereas in North Cove 60% of markers were destroyed. There were significant differences in scouring frequency between our two sites: a given area in North Cove was on average hit twice as often as one in South Cove. Compared with near shore environments elsewhere, faunas of both sites were characteristic of high disturbance regimes, exhibiting low percent cover, diversity, ages and a high proportion of pioneers. Aspects of the encrusting communities studied reflected the differences between site disturbance regimes. North Cove was scoured twice as often, and bryozoan communities there had half the number of species, two-thirds the space occupation and twice the mortality level of those in South Cove. Maximum age in North Cove bryozoans was also half that in South Cove. Although there are natural disturbance events that rival ice-scouring in either frequency or catastrophic power at lower latitudes, none do both nor across such a wide depth range. We suggest that ice scour effects on polar benthos are even more significant than the same magnitude of disturbance at lower latitudes as recovery rates of high latitude communities are very slow. Climate warming seems likely to increase iceloading of near shore polar waters, so that some of the worlds most intensely disturbed faunas may soon suffer even more disturbance.     

Effect of dolomite on the repair of bone defects in rats: histological study

The aim of the present study was to evaluate histologically and radiographically the tissue response to dolomite [CaMg(CO3)2] and its osteogenic potential in the repair of bone cavities in the calvaria of rats. A bone defect 10 mm in diameter and 1 mm deep was made in the calvaria of male Wistar rats. The defects were filled with dolomite, inorganic bovine bone (positive control), or coagulum (negative control). The animals were euthanized 7, 15, 30, and 60 days after surgery, and specimens were collected for radiographic and microscopic analyses. The bone defects were processed for paraffin embedding and H&E staining. The histological study revealed that dolomite stimulated a moderate inflammatory response, with programmed cell death in the first 15 days, compared to bovine bone which showed a moderate to intense acute response. In the chronic phase, the inflammatory response was characterized by the occurrence of macrophages organized as epithelioid cells in the dolomite group, and giant cells in the bovine-bone group. Fibrosis developed in all three groups; however, encapsulation of the fragments, reabsorption, and osteoconductive activity occurred only in the defects filled with bovine bone. The radiographic analysis showed that the bovine bone was most efficient in the repair of the defects, followed by the dolomite and the coagulum. This study demonstrated that the dolomite stimulated a moderate acute inflammatory response with programmed cell death, and a chronic inflammatory response by means of the phagocytic mononuclear system. Although osteo-conductive activity was not shown, the dolomite favored the repair process, compared to the coagulum group.     

Evidence for phylogeographic structure in Lolium species related to the spread of agriculture in Europe. A cpDNA study

In order to explain the present distribution area of natural populations of two forage grasses species (Lolium perenne and L. rigidum), we studied genetic variation for maternally inherited chloroplast DNA (cpDNA) in 447 individual plants from 51 natural populations sampled throughout Europe and the Middle East. The detection of polymorphism by restriction analysis of PCR-amplified cpDNA fragments resulted in the identification of 15 haplotypes. Hierarchical analysis of chloroplastic diversity showed a high level of within-population diversity while, for both species, we found that about 40% of the total diversity still remains among populations. The use of previous isozymes data enabled us to estimate the pollen to seed flow ratio: pollen flow appears to be 3.5 times greater than seed flow for L. perenne and 2.2 times higher for L. rigidum. A stepwise weighted genetic distance between pairs of populations was calculated using the haplotypes frequencies of populations. A hierarchical clustering of populations clearly divides the two species, while two main clusters of L. perenne populations show a strong geographical structure. Different scenario are proposed for explaining the distribution area of the two species. Finally, evidence attesting that these geographical structures are related to the spread of agriculture in Europe are presented and discussed. Received: 5 November 1999 / Accepted: 24 November 1999     

A histological study of cutaneous glands in the brown brocket deer

We examined the histological structure of 8 skin areas thought to contain cutaneous glands of potential importance in scent communication in 16 brown brocket deerMazama gouazoubira Fisher, 1814, using standard histological techniques. Frontal areas and preorbital sacs had scant glandular development. Sebaceous gland development was prominent in vestibular nasal glands and prepucial glands. Apocrine sudoriferous glands and sebaceous glands were well developed in tarsal glands, the caudal skin area and the interdigital glands of front and hind feet. The tail had a unique arrangement of apocrine sudoriferous glands. Anal glands had moderate glandular development, and metatarsal glands were absent. Several of these glandular areas may be important in the chemical communication among brocket deer.     

A pilot study on the prevalence of maternal obesity in selected Greek counties

ObjectiveTo report a pilot prevalence of maternal overweight, obesity and underweight in selected Greek counties.MethodsA total of 441 adult childbearing women were recruited from maternity clinics in 6 Greek counties for this cross-sectional study. Pre-gravid weight status was defined according to the WHO cut-offs and gravid weight status was diagnosed with the Mardones and Rosso weight gain chart.ResultsDuring gestation the majority of the participants were of normal body weight (BW) (34.0%), obesity was apparent in 25.6% of the sample, 23.8% of the participants were underweight, and the remaining 16.6% were overweight. Overall, pregnancy tripled the prevalence of underweight, increased the prevalence of obesity (by 388.0%) and decreased the number of participants in the normal BW category (p ≤ 0.001 for all). The majority of participants classified in each pre-gravid weight-category remained in the same weight category during their gestation. All the pre-gravidly obese women were also obese during pregnancy. Underweight was more prevalent in Kavala (37.5%) and obesity was more frequent in Thessaloniki (30.8%). Women who were overweight prior to conception were highly likely to be overweight/obese during pregnancy (OR: 23.8, CI: 11.1–51.0).ConclusionsThe results indicate a high prevalence of overweight, obesity and underweight among pregnant women in Greece.     

阜阳地区居室环境中粉螨的群落组成和多样性

目的调查安徽省阜阳地区居室环境中粉螨的群落组成和多样性。方法于2009年7月,选择100户家庭进行样本采集,每居室环境中取4个采样点,对采集到的地面灰尘、床面灰尘、家具灰尘及衣物灰尘进行粉螨的分离、鉴定、计数和数据分析。结果共检获粉螨3609只,隶属于6科15属,共19种。对4类居室灰尘中粉螨群落多样性分析表明:它们的丰富度指数为0.89~2.09,多样性指数为1.28~1.83,均匀度指数为0.65~0.71。结论粉螨群落的结构及多样性与其生境条件直接相关;阜阳地区人居环境粉螨孳生密度较高(48.5%),应加强防螨措施。     

A histological study on the coronary artery of the indigenous black Bengal goat in Bangladesh.

The coronary artery of the black Bengal goat was studied by light microscopy. The wall of the coronary artery consisted of the tunica intima, tunica media and tunica externa. The tunica intima consisted of a single layer of flattened endothelium. The tunica media was well-developed and composed of mainly of smooth muscle cells together with some fine elastic fibers. The tunica externa consisted of predominant collagen fibers, and some elastic fibers and smooth muscle cells. Elastic fibers in the tunica externa formed a circular arrangement around the tunica media. Sex differences were not observed. The media with well-developed smooth muscle cells may be responsible for changes in functional physiological conditions of the heart.     

Fish assemblage structure on a drowned barrier island in the northwestern Gulf of Mexico

We investigated the assemblage structure of fishes associated with different habitats (inshore mud, shell bank, and offshore mud) over a drowned barrier island, Freeport Rocks Bathymetric High, on the inner continental shelf of the northwestern Gulf of Mexico (NW Gulf). Density data from otter trawls were used to examine spatial (habitat and site) and temporal differences in fish assemblage structure using multi- and univariate procedures. Eight species accounted for 69% of the total composition and in order of decreasing abundance included shoal flounder (Syacium gunteri), dwarf sand perch (Diplectrum bivittatum), red snapper (Lutjanus campechanus), least puffer (Sphoeroides parvus), silver seatrout (Cynoscion nothus), largescale lizardfish (Saurida brasiliensis), silver jenny (Eucinostomus gula), and sand seatrout (Cynoscion arenarius). Multivariate results indicated fish assemblage structure differed among habitats (ANOSIM; Global R = 0.190, P < 0.001) and survey dates (ANOSIM; Global R = 0.541, P < 0.001); however, differences among sites were negligible (ANOSIM; Global R = −0.015, P = 0.749). Highest densities of dwarf sand perch and least puffer were found on the shell bank, while densities of shoal flounder, largescale lizardfish, and silver jenny were highest on offshore mud. In addition, smallest sizes and highest densities of six of the eight abundant species were found in July, suggesting an important period for juvenile fishes. Diversity indices also varied relative to habitat with highest Shannon diversity (H′) and species richness (S) values for fishes associated with the shell bank. Results of this study highlight the importance of a mosaic of habitat types to fish assemblages on a drowned barrier island in the NW Gulf. Handling editor: I. Nagelkerken     

A histological study of toxic effects of aluminium sulfate on rat hippocampus

Abstract

Aluminium has toxic effects on many organ systems of the human body. Aluminium toxicity also is a factor in many neurodegenerative diseases. We investigated changes in numbers of hippocampal neurons in rats exposed to aluminium using an optical fractionator and we investigated aluminium-induced apoptosis using the transferase mediated dUTP nick end labeling (TUNEL) assay. Twenty-four female rats were divided equally into control, sham and aluminium-exposed groups. The control group received no treatment. The two treatment groups were injected intraperitoneally with 1 ml 0.9% saline without (sham) and with 3 mg/ml aluminium sulfate every day for two weeks. Following the treatments, the brains were removed, the left hemisphere was used for hippocampal neuron counting using an optical fractionator and the right hemisphere was investigated using hippocampal TUNEL assay to determine the apoptotic index. The number of neurons in the stratum pyramidale of the hippocampus was significantly less in the aluminium group than in the control and sham groups; there was no significant difference between the control and sham groups. The apoptotic index also was significantly higher in the aluminium group than in the other two groups. We quantified the toxic effects of aluminium on the rat hippocampus and determined that apoptosis was the mechanism of aluminium-induced neuron death in the hippocampus.     

Application of multivariate methods to a study of community composition and structure in an escarpment woodland in northeast Ireland

Multivariate models based independently on the floristic and environmental attributes of sample quadrats from an escarpment woodland, were constructed. They were used to interpret the ecology of plant species distribution and to investigate the size structure of tree populations. Site instability, soil water status, and past management and grazing pressure were found to exert major influences on the composition and structure of the woodland. It is suggested that early mortality associated with site instability, plays an important role in maintaining the floristic diversity of vascular plants in the woodland ground flora, by increasing the frequency of tree replacement. This may have the effect of preventing canopy closure and any associated, detrimental effects of low light intensities. The relevance of the work of the conservation management of escarpment woods in Northern Ireland is discussed.