A standard tissue as a control for histochemical and immunohistochemical staining

The variable quality of histochemical and immunohistochemical staining of tissues may be attributed to pre-analytical and analytical variables. Both categories of variables frequently are undefined or inadequately controlled during specimen collection and preparation. Pre-analytical variables may alter the molecular composition of tissues, which results in variable staining; such variations may cause problems when different tissues are used as staining controls. We developed a standard tissue for use as a staining control. Our standard tissue contains five components: 1) nine combined human cell lines mixed with stroma from human spleen; 2) a squamous cancer cell line, A431; 3) fungus; 4) transverse sections of the mosquitofish and 5) normal human spleen. The first three components were embedded in HistoGel^? and all components were processed to paraffin and used to construct a single standard paraffin block. The muscles of mosquitofish and arteries of the spleen are positive controls for eosin staining, while other tissues are useful for assessing hematoxylin staining. The mosquitofish tissues also are excellent controls for the Masson trichrome stain and all mucin-related histochemical stains that we tested. The goblet cells of the intestine and skin stained strongly with Alcian blue, pH 2.5 (AB-2.5), mucicarmine, colloidal iron, periodic acid Schiff (PAS) or PAS-hematoxylin (PASH) and combination stains such as colloidal iron-PASH. Cell lines were not useful for evaluating histochemical stains except for PASH. The splenic stroma was a useful control for AB-2.5; however, eosin and mucin stains stained cell lines poorly, probably due to their rapid growth and associated loss of some differentiated characteristics such as production of mucins. Nevertheless, the cell lines were a critical control for immunohistochemical stains. Immunostaining of specific cell lines was consistent with the presence of markers, e.g., EGFr in DU145 cells. The cell lines expressed a wide range of markers, so they were useful controls for immunohistochemical staining including EGFr, HER2, E-cadherin, cytokeratins, Ki67, PCNA, estrogen receptor, progesterone receptor, CD3, CD20 and CD45, activated (cleaved) caspase 3 and Bcl-2. The cell lines also were a control for the TUNEL stain.     

Interspecific variation of body shape and sexual dimorphism in three coexisting species of the genus <Emphasis Type="Italic">Petrotilapia</Emphasis> (Teleostei: Cichlidae) from Lake Malawi

Differences in color patterns have been the most used feature in describing cichlid species belonging to genus Petrotilapia from Lake Malawi. In this study, we quantified morphological variation in body shape within and among three coexisting Petrotilapia species using landmark-based geometric morphometric methods. Statistic analyses revealed significant body shape differences among species but not between sexes. Post hoc multiple comparisons based on Mahalanobis distances revealed that P. nigra was significantly different from P. genalutea and Petrotilapia sp., whereas the latter two were not significantly different. The splines generated showed that the most pronounced variation was in the head region, in which P. nigra had a relatively longer and deeper head than the other two. The most clear-cut distinction was in gape length; P. genalutea had the longest gape, followed by Petrotilapia sp., whereas P. nigra had the shortest gape. Body depth was shallower in P. nigra than the others. When comparing sexes by their centroid size, ANOVA revealed that males were bigger than females. Therefore, we conclude that color is not the only feature that can distinguish these congeners. We discuss the observed sexual dimorphism in terms of sexual selection and relate morphological variation among species to feeding behavior, which may help explain their coexistence in nature.     

Trehalose Increases Freeze-Thaw Damage in Liposomes Containing Chloroplast Glycolipids

Chloroplast thylakoids contain three classes of glycolipids, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG). We have investigated the stability of large unilamellar vesicles made from egg phosphatidylcholine (EPC) and different chloroplast glycolipids during freezing to -18 degreesC, as a function of the presence of three sugars: glucose, sucrose, or trehalose. Contrary to the situation in thylakoids, where cryoprotection increases from glucose < sucrose < trehalose, liposomes containing 50% DGDG showed the opposite behavior. In fact, carboxyfluorescein leakage increased over the control values (freezing in the absence of sugar) in the presence of trehalose. This effect was not seen in vesicles made from pure EPC, or a mixture of EPC and MGDG, or EPC and SQDG. Liposomes made from mixtures of all three glycolipids, however, showed even more leakage in the presence of trehalose than liposomes containing only DGDG and EPC. Copyright 1998 Academic Press.     

Lumbar muscle electromyographic dynamic topography during flexion-extension

The objective of this study is to introduce dynamic topography of surface electromyography (SEMG) to visualize lumbar muscle myoelectric activity and provides a new view to analyze muscle activity in vivo. A total of 20 healthy male subjects and 15 males LBP were enrolled. An electrode-array was applied to the lumbar region to collect SEMG. The root mean square (RMS) value was calculated for each channel, and then a 160×120 matrix was constructed using a linear cubic spline interpolation of each scan to create a 2-D color topographic image. Along a definite interval of action, a series of RMS topography matrices was concatenated as a function of position and time, to form a dynamic topographical video of lumbar muscle activity. Relative area (RA), relative width (RW), relative height (RH) and Width-to-Height Ratio (W/H) were chosen as the four quantitative parameters in measuring topographic features. Normal RMS dynamic topography was found to have a consistent, symmetric pattern with a high intensity area in the paraspinal area. LBP patients had a different RMS dynamic topography, with an asymmetric, broad, or disorganized distribution. Quantitative SEMG features were found significantly different between normal control and LBP. After physiotherapy rehabilitation, the dynamic topography images of LBP tended towards the normal pattern.There are obvious differences in lumbar muscle coordination between healthy subjects and LBP patients. The dynamic topography allows the continuous visualization of the distribution of surface EMG signals and the coordination of muscular contractions.     

The fission yeast kinetochore component Spc7 associates with the EB1 family member Mal3 and is required for kinetochore-spindle association

A critical aspect of mitosis is the interaction of the kinetochore with spindle microtubules. Fission yeast Mal3 is a member of the EB1 family of microtubule plus-end binding proteins, which have been implicated in this process. However, the Mal3 interaction partner at the kinetochore had not been identified. Here, we show that the mal3 mutant phenotype can be suppressed by the presence of extra Spc7, an essential kinetochore protein associated with the central centromere region. Mal3 and Spc7 interact physically as both proteins can be coimmunoprecipitated. Overexpression of a Spc7 variant severely compromises kinetochore-microtubule interaction, indicating that the Spc7 protein plays a role in this process. Spc7 function seems to be conserved because, Spc105, a Saccharomyces cerevisiae homolog of Spc7, identified by mass spectrometry as a component of the conserved Ndc80 complex, can rescue mal3 mutant strains.     

The fission yeast ran GTPase is required for microtubule integrity

The microtubule cytoskeleton plays a pivotal role in cytoplasmic organization, cell division, and the correct transmission of genetic information. In a screen designed to identify fission yeast genes required for chromosome segregation, we identified a strain that carries a point mutation in the SpRan GTPase. Ran is an evolutionarily conserved eukaryotic GTPase that directly participates in nucleocytoplasmic transport and whose loss affects many biological processes. Recently a transport-independent effect of Ran on spindle formation in vitro was demonstrated, but the in vivo relevance of these findings was unclear. Here, we report the characterization of a Schizosaccharomyces pombe Ran GTPase partial loss of function mutant in which nucleocytoplasmic protein transport is normal, but the microtubule cytoskeleton is defective, resulting in chromosome missegregation and abnormal cell shape. These abnormalities are exacerbated by microtubule destabilizing drugs, by loss of the spindle checkpoint protein Mph1p, and by mutations in the spindle pole body component Cut11p, indicating that SpRan influences microtubule integrity. As the SpRan mutant phenotype can be partially suppressed by the presence of extra Mal3p, we suggest that SpRan plays a role in microtubule stability.