Molecular evolution of the ZFY and ZNF6 gene families

Members of the ZFY and ZNF6 gene families have been cloned from species representing different taxa and different modes of sex determination. Comparisons of these genes show the ZFY-like and ZNF6 sequences to be strongly conserved across marsupials, birds, and lepidosaurians. Sequence analyzed by neighbor-joining indicated that both gene families are monophyletic with a high bootstrap value. Pairing of sequences from males and females of nonmammalian species showed there to be no significant difference between male and female sequences from a single species, consistent with autosomal locations. The molecular distances between murine Zfy-1, Zfy-2, and other ZFY-like sequences suggested that Zfy genes have undergone a period of rapid evolutionary change not seen in human ZFY.      

Matrix metalloproteinases: old dogs with new tricks

The matrix metalloproteinase family in humans comprises 23 enzymes, which are involved in many biological processes and diseases. It was previously thought that these enzymes acted only to degrade components of the extracellular matrix, but this view has changed with the discovery that non-extracellular-matrix molecules are also substrates.     

An international survey of patients with thalassemia major and their views about sustaining life-long desferrioxamine use

Background  

Management of thalassemia major requires patients to have life-long access to a treatment regimen of regular blood transfusions coupled with iron chelation therapy. The objective of this study was to investigate patients' reasons for missing iron chelation therapy with desferrioxamine, and the support to sustain life-long adherence to treatment.     

Ultrastructural and Morphological Characteristics of Cultivated Wheat Growing on Copper-Polluted Fields

A cultivated Greek variety of wheat (Triticum aestivum L. cv. Vergina) growing in fields naturally polluted by outcrops of copper ores was investigated. Wheat plants show a negative response to increasing quantities of soil copper, including reduced growth and chlorosis. Copper toxicity was demonstrated in the laboratory by a rooting test; the frequency of mitoses declines sharply with increasing copper concentration in the nutrient solution. The mesophyll cells of polluted plants display a circular shape (in transverse sections) with a few chloroplasts parietally distributed, in contrast with the elongate or pleomorphic shape of control leaves that contain numerous chloroplasts crowded at the cell periphery. Ultrastructurally, the chloroplasts of polluted plants contain a poorly developed internal membrane system consisting of thylakoids arranged parallel to each other with only a few, rudimentary grana. In addition, a number of statistically significant differences were found, including the number of starch grains and plastoglobuli, chloroplast surface area, volume fraction of starch grains and, most important, the volume fraction of the internal membrane system. All ultrastructural changes are attributed to the toxic effect of high concentrations of soil copper.     

Abnormal structure of protophloem sieve-element cell wall in colchicine-treated roots of Triticum aestivum L.

The structural aberrations of the cell walls of protophloem sieve elements (PSEs) in roots of wheat (Triticum aestivum L. cv. Maris Huntsman) caused by the anti-microtubule drug colchicine were investigated by electron microscopy. The initial effect of the drug on cell wall development was found to be an exceptionally rough wall surface, presumably caused by an uncontrolled fusion of Golgi vesicles with the plasma membrane. Cellulose microfibrils, which in normal PSEs are aligned transversely to the long axis and parallel to the cortical microtubules, in colchicine-treated PSEs display a predominant longitudinal orientation. The pattern of wall development is disturbed by deposition of wall material also within the sieve pores of the sieve-pore/plasmodesmata complexes, resulting in evenly thickened walls instead of the normal uneven layers, and in narrowing the sieve pores to the size of plasmodesmata. In prolonged and continuous colchicine treatment, PSEs develop unusual wall ingrowths projecting deeply into the cytoplasm, creating an extraordinary cell type not found in normal roots. The results confirm the view of microtubule involvement in the proper deposition and orientation of cellulose microfibrils, and in the normal patterning of the cell wall thickenings of differentiating PSEs.Abbreviations c colchicine-treated - PSE protophloem sieve element The author is grateful to Dr. B. Galatis, Dr. P. Apostolakos and Dr. C. Katsaros, Institute of General Botany, University of Athens, Greece, for helpful discussions and suggestions, and for the generous gift of the colchicine used here. This work was carried out in the Department of Botany, University of Thessaloniki, Greece, while observations were also made in the Lehrstuhl für Zellenlehre, University of Heidelberg, Germany, and in the Department of Botany, University of Georgia, USA. The author is thankful to Prof. E. Schnepf (Zellenlehre, Heidelberg, Germany) and Prof. B.A. Palevitz (Department of Botany, University of Athens, Ga., USA), for generously providing access to their equipment and facilities. The work was financially supported in part by the Stiftung Volkswagenwerk and by the Research Committee, University of Thessaloniki (No 7537).     

The effect of recaging into groups or into isolation on the pituitary adrenal response to immobilization of different age groups of C57BL/6J mice

Although there is evidence which suggests that age and social environment are significant variables in all experiments dealing with stress in intact animals, there is relatively little information available on the manner in which these variables interact to influence the pituitary adrenal response to stress. Inbred mice of strain, C57BL/6J, of 3 different age groups (49, 255 and 720 days) were subjected to a brief immobilization stress 24 hours subsequent to regrouping them 1, 2 or 4 per cage. Plasma corticosterone concentration was measured by radioimmunoassay prior to and 15 minutes after immobilization or 60 minutes after treatment with ACTH. It was found that preimmobilization levels of corticosterone and increments in corticosterone in response to ACTH treatment were smaller in 255 day than in 49 or 720 day old mice and that preimmobilization corticosterone levels of control and recaged 49 and 255 day old mice were similar. In 49 day old mice, recaging increased the immobilization evoked increment in corticosterone, but in 255 and 720 day old mice recaging in groups or pairs did not change the immobilization evoked response. However, recaging of 720 day old mice in isolation resulted in a decrease in the immobilization evoked increment. Therefore, it appears that the act of transfer itself increased the pituitary adrenal function in the 49 day old mice while, in the oldest mice, isolation itself reduced pituitary adrenal activity. Finally, it appears that in the 255 day old mice, recaging is only a minor stress since after 24 hours′ there is no evidence of elevated steroid levels.     

Do multivariate analyses incorporating changes in pattern across taxonomic levels reveal anthropogenic stress in Mediterranean lagoons?

It is accepted that observed patterns in community structure change as analyses are carried out at higher taxonomic levels. Univariate analyses which incorporate higher taxonomic structure within assemblages have been shown to be informative. In this paper we suggest ways in which changes in multivariate relationships at higher taxonomic levels and associated with higher taxonomic/phylogenetic structure of the community may be incorporated into multivariate analyses, an aspect never occurred before in this type of analysis. Four approaches, namely: biodiversity MDS (bdMDS), number of taxa MDS (ntMDS), delta MDS (δMDS) and lambda MDS (λMDS), are proposed, and applied to theoretical data as well as to data collected from the literature on the Mediterranean lagoonal environment. Results show that these approaches have the capacity to distinguish severely impacted lagoons from naturally disturbed ones, although in practice the simplest method (ntMDS) was the most successful. Analyses based on the most abundant groups (polychaetes, molluscs, crustaceans) did not always match analyses based on the entire macrofauna, mirroring the performance of taxonomic distinctness indices in the Mediterranean lagoons. The important characteristics of the approaches introduced, as well as potential criticisms are provided. Application of these techniques on smaller scales and to other habitats, is suggested prior to their wider use in the region.     

TGF beta-induced focal complex formation in epithelial cells is mediated by activated ERK and JNK MAP kinases and is independent of Smad4

Advanced malignancies often exhibit increased concentrations of transforming growth factor-beta (TGF beta), which has been suggested to promote invasion and metastasis. While inhibition of epithelial cell proliferation in response to TGF beta is mainly mediated by the well-characterised Smad pathway, the molecular mechanism leading to TGF beta-induced invasiveness and metastasis are largely unknown. To elucidate these mechanisms, we compared TGF beta1 signalling in MCF-7 and the Smad4-negative MDA-MB-468 breast cancer cells. Both cell lines react to TGF beta1 treatment with decreased subcortical actin and increased numbers of focal contacts. TGF beta1-induced cell migration was strongly dependent on the activation of extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK). These mitogen-activated protein kinases were phosphorylated in response to TGF beta and subsequently translocated into focal contacts. Inhibition of the TGF beta type I receptor ALK5 slightly reduced phosphorylation of ERK in MCF-7 cells, but neither inhibited phosphorylation of ERK in MDA-MB-468 cells nor TGF beta1-induced migration of both cell lines. In contrast, ALK5 inhibition effectively blocked Smad2 phosphorylation. In addition to ERK and JNK, the monomeric GTPase RhoA was activated by TGF beta1 and necessary for TGF beta-induced migration. Taken together, our study identifies a role of ERK and JNK activation and association of activated MAPKs with focal complexes in TGF beta1-induced cell migration in epithelial cells. These TGF beta-dependent processes were mediated independently of Smad4.