The effect of shrub clearing and grazing on the composition of a Mediterranean plant community: functional groups versus species

Abstract. Fuel-breaks to impede the spread of fires in Mediterranean woody vegetation are created by clearing of shrubs, followed by very intensive cattle grazing before the fire season. The present research analysed the effects of these two disturbance types on herbaceous community composition at the functional group and the species level, by using canonical discriminant ordination analysis and by categorical modeling methods. Grazing caused an increase in the abundance of small species, geophytes, and species with an early flowering period that ends before the grazing period. The abundance of many different species increased as a result of clearing. However, no association was found between positive or negative response to clearing and any species attribute tested. Several a priori functional groups defined by life form and family showed responses to either grazing or clearing. Links between these responses and individual species attributes are discussed. The results emphasize the different nature of the two disturbances: grazing as a selective agent, and shrub clearing as a generalized one. It also stresses the importance of the plant architecture and the morphological and phenological niche in determining community composition under extremely intensive grazing conditions.     

Trophoblasts isolated from the maternal circulation: in vitro expansion and potential application in non-invasive prenatal diagnosis.

Prenatal diagnosis based on rare fetal cells in maternal blood is currently not a feasible option. An effort was made to improve cell yields by targeting trophoblast cells. After sorting, the HLA-G-positive cell fraction was analyzed directly or after culture. In situ hybridization technology was applied to prove fetal cell source in samples from women carrying a male fetus and to predict gender in samples without previous knowledge of fetal sex. In vitro culture led to a significant increase in fetal cells and accurate gender prediction in 93% of these samples. This approach might be useful for non-invasive prenatal diagnosis.     

Automatic retrieval of single microchimeric cells and verification of identity by on‐chip multiplex PCR

The analysis of rare cells is not an easy task. This is especially true when cells representing a fetal microchimerism are to be utilized for the purpose of non‐invasive prenatal diagnosis because it is both imperative and difficult to avoid contaminating the minority of fetal cells with maternal ones. Under these conditions, even highly specific biochemical markers are not perfectly reliable. We have developed a method to verify the genomic identity of rare cells that combines automatic screening for enriched target cells (based on immunofluorescence labelling) with isolation of single candidate microchimeric cells (by laser microdissection and subsequent laser catapulting) and low‐volume on‐chip multiplex PCR for DNA fingerprint analysis. The power of the method was tested using samples containing mixed cells of related and non‐related individuals. Single‐cell DNA fingerprinting was successful in 74% of the cells analysed (55/74), with a PCR efficiency of 59.2% (860/1452) for heterozygous loci. The identification of cells by means of DNA profiling was achieved in 100% (12/12) of non‐related cells in artificial mixtures and in 86% (37/43) of cells sharing a haploid set of chromosomes and was performed on cells enriched from blood and cells isolated from tissue. We suggest DNA profiling as a standard for the identification of microchimerism on a single‐cell basis.     

Maternal environmental contribution to adult sensitivity and resistance to obesity in Long Evans rats

Background

The OLETF rat is an animal model of early onset hyperphagia induced obesity, presenting multiple pre-obese characteristics during the suckling period. In the present study, we used a cross-fostering strategy to assess whether interactions with obese dams in the postnatal environment contributed to the development of obesity.

Methodology

On postnatal Day (PND)-1 OLETF and control LETO pups were cross-fostered to same or opposite strain dams. An independent ingestion test was performed on PND11 and a nursing test on PND18. Rats were sacrificed at weaning or on PND90, and plasma leptin, insulin, cholesterol, triglycerides and alanine aminotransferase (ALT) were assayed. Fat pads were collected and weighed and adipocyte size and number were estimated. Body weight and intake, as well as the estrous cycle of the female offspring were monitored.

Principal Findings

During the suckling period, the pups'' phenotype was almost completely determined by the strain of the mother. However, pups independently ingested food according to their genotype, regardless of their actual phenotype. At adulthood, cross fostered males of both strains and LETO females were affected in regard of their adiposity levels in the direction of the foster dam. On the other hand, OLETF females showed almost no alterations in adiposity but were affected by the strain of the dams in parameters related to the metabolic syndrome. Thus, OLETF females showed reduced liver adiposity and circulating levels of ALT, while LETO females presented a disrupted estrous cycle and increased cholesterol and triglycerides in the long term.

Conclusions

The present study provides further support for the early postnatal environment playing a sex-divergent role in programming later life phenotype. In addition, it plays a more central role in determining the functioning of mechanisms involved in energy balance that may provide protection from or sensitivity to later life obesity and pathologies related to the metabolic syndrome.     

IFN-gamma acts on T cells to induce NK cell mobilization and accumulation in target organs

The mechanism(s) that regulates NK cell mobilization and the significance of this process to NK cell activity are unknown. After Con A-induced hepatitis, NK cells are mobilized from the spleen and bone marrow into the periphery in an IFN-gamma-dependent fashion. Intraperitoneal administration of IFN-gamma stimulates the mobilization of NK cells into the circulation, but not their cell death or proliferation. Increased number of circulating NK cells was coupled with their accumulation in the peritoneum, liver, and tumor-bearing lung tissue. Furthermore, increased number of NK cells in the lung reduced metastasis of Lewis lung carcinoma cells (3LL cell line) resulting in significantly extended NK-dependent survival. Mobilization of NK cells was specific and required the presence of T cells. Moreover, mobilization and migration of spleen NK cells in response to IFN-gamma treatment is dependent on the chemokine receptor CXCR3. Mechanistic insights regarding the role of IFN-gamma in the regulation of NK cell mobilization and their accumulation at sites of tumor metastasis may lead to the development of novel immunotherapy for cancer.     

Gene-environment interactions in sporadic Parkinson's disease

Much has been learned in recent years about the genetics of familial Parkinson's disease. However, far less is known about those malfunctioning genes which contribute to the emergence and/or progression of the vast majority of cases, the 'sporadic Parkinson's disease', which is the focus of our current review. Drastic differences in the reported prevalence of Parkinson's disease in different continents and countries suggest ethnic and/or environmental-associated multigenic contributions to this disease. Numerous association studies showing variable involvement of multiple tested genes in these distinct locations support this notion. Also, variable increases in the risk of Parkinson's disease due to exposure to agricultural insecticides indicate complex gene-environment interactions, especially when genes involved in protection from oxidative stress are explored. Further consideration of the brain regions damaged in Parkinson's disease points at the age-vulnerable cholinergic-dopaminergic balance as being involved in the emergence of sporadic Parkinson's disease in general and in the exposure-induced risks in particular. More specifically, the chromosome 7 ACHE/PON1 locus emerges as a key region controlling this sensitive balance, and animal model experiments are compatible with this concept. Future progress in the understanding of the genetics of sporadic Parkinson's disease depends on globally coordinated, multileveled studies of gene-environment interactions.     

Health Perceptions,Self and Body Image,Physical Activity and Nutrition among Undergraduate Students in Israel

Purpose

This study examines health perceptions, self and body image, physical exercise and nutrition among undergraduate students.

Methods

A structured, self-reported questionnaire was administered to more than 1500 students at a large academic institute in Israel. The study population was heterogenic in both gender and fields of academic study.

Results

High correlations between health perceptions, appropriate nutrition, and positive self and body image were found. The relationships between these variables differed between the subpopulation in the sample and the different genders. Engagement in physical exercise contributed to positive body image and positive health perceptions more than engagement in healthy nutrition. Nutrition students reported higher frequencies of positive health perceptions, positive self and body image and higher engagement in physical exercise in comparison to all other students in the sample.

Conclusions

This study suggests, as have many before, that successful health promotion policy should reflect a collectivist rather than an individualist ethos by providing health prerequisites through a public policy of health-promotion, where the academic settings support a healthy lifestyle policy, by increasing availability of a healthy, nutritious and varied menu in the cafeterias, and offering students various activities that enhance healthy eating and exercise.

Implications and contribution

This study examined health perceptions, self-image, physical exercise and nutrition among undergraduate students and found high correlations between these topics. Nutrition students reported higher frequencies of positive health perceptions, and positive self and body image and engaged more in physical exercise when compared with all other students in the sample.     

Ongoing Pregnancy Rates in Women with Low and Extremely Low AMH Levels. A Multivariate Analysis of 769 Cycles

Background

The ideal test for ovarian reserve should permit the identification of women who have no real chance of pregnancy with IVF treatments consequent upon an extremely reduced ovarian reserve. The aim of the current study was to evaluate pregnancy rates in patients with low AMH levels (0.2–1 ng/ml) and extremely low AMH levels (<0.2 ng/ml) and to determine the cumulative pregnancy rates following consecutive IVF treatments.

Methods

We conducted an historical cohort analysis at a tertiary medical center. Serum AMH levels were measured at initial clinic visit and prior to all following treatment cycles in 181 women (769 cycles) with an initial AMH level ≤1 ng/ml, undergoing IVF-ICSI. Main outcome measures were laboratory outcomes and pregnancy rates.

Results

Seventy patients undergoing 249 cycles had extremely low AMH levels (≤0.2 ng/ml), whereas 111 patients undergoing 520 cycles had low AMH levels (0.21–1.0 ng/ml). Number of oocytes retrieved per cycle, fertilized oocytes and number of transferred embryos were significantly lower in the extremely low AMH levels group compared to the low AMH levels (P<0.003). Crude ongoing pregnancy rates were 4.4% for both groups of patients. Among 48 cycles of women aged ≥42 with AMH levels of ≤0.2 ng/ml no pregnancies were observed. But, in patients with AMH levels of 0.2–1.0 ng/ml, 3 ongoing pregnancies out of 192 cycles (1.6%) were observed. However, in a multivariate regression analysis adjusted for age and cycle characteristics, no significant differences in ongoing pregnancy rates per cycle between the two groups were evident. Cumulative pregnancy rates of 20% were observed following five cycles, for both groups of patients.

Conclusions

Patients with extremely low AMH measurements have reasonable and similar pregnancy rates as patients with low AMH. Therefore, AMH should not be used as the criterion to exclude couples from performing additional IVF treatments.