Changes in number,cell shape and adhesiveness induced by dopamine on chick primordial germ cells

Summary Dopamine (DA), injected beneath the blastodisc of the chick embryo before the beginning of incubation, induced an approximately 2.5 times increase in the total number of primordial germ cells (PGCs) at the definitive primitive streak stage. It also produced changes in the shape and behaviour of PGCs since more than half of them adhered to one another, forming groups or chains of three or more cells and, in contrast to their characteristic spherical form, most single PGCs displayed a fibroblastic appearance. On the 2nd day of incubation most PGCs remained adherent to each other, which did not hinder them from entering the extra-embryonic blood vessels of the crescent. Ultrastructural analysis showed that PGCs adhered to each other by large areas of cell membrane apposition and specialized adhesive structures, such as tight junctions and desmosomes. PGCs also displayed many lamellipodial and filopodial processes. The effects of DA on PGCs were prevented by either glucose or EDTA. Although it is difficult to account for the effect of glucose, the effect of EDTA suggests that the action of DA may be calcium-dependent.     

Effects of catecholamines on early development of the chick embryo: relationship to effects of calcium and cAMP

Catecholamines (dopamine or norepinephrine) injected under the blastoderm of the unincubated chick embryo produced a thickened primitive streak and prevented the migration of axial mesoblast after 24 h. The mesoblastic cells that accumulated in the primitive streak contained many intracytoplasmic yolk granules. After 48 h, neural tube, notochord, and somites were severely affected, and their cells appeared loaded with yolk inclusions. Heart, lateral plates, blood cells, and blood vessels differentiated normally. At the onset of gastrulation, the level of glycogen was fivefold lower in catecholamine-treated embryos than in control embryos. Injection of glucose plus dopamine, at equimolar concentrations resulted in normal development both at 24 h and at 48 h. Because adrenergic stimulation of glycogenolysis in differentiated cells is usually mediated by cAMP and/or by calcium, we attempted to determine whether these substances could reproduce the effects of catecholamines. Only calcium was able to produce, to a limited extent, the same morphogenetic disturbances as those produced by catecholamines, whereas the chelating agent, ethylenediamine tetraacetic acid, when administered with dopamine, partially inhibited the effects of catecholamines. An increase in the number of yolk granules was the only common finding among embryos treated with cAMP and catecholamines. Blood and a well differentiated, gastrular endoderm always developed, independently of the nature of the substance with which the embryos had been treated. Morphogenetic disturbances caused by exogenous catecholamines could be due to depletion of glucose. Alternatively, a different metabolic commitment might exist within the diverse populations of cells that constitute the mesoblastic layer.     

Nuclear location of phosphoglycerate mutase BB isozyme in rat tissues.

We have previously reported (Ure?a et al. Eur. J. Cell Biol. 1990) that in skeletal muscle, type MM phosphoglycerate mutase isozyme is present in the nucleus as well as in the cytosol. To determine whether type BB phosphoglycerate mutase isozyme is also present in nucleus, the subcellular location of this isozyme was studied in different rat tissues by cell fractionation and immunogold techniques. With the aid of high affinity-purified anti-phosphoglycerate mutase BB isozyme antibodies, the isozyme was located in the nucleus of neuronal, astroglial and liver cells but not in the nucleus of oligodendroglial and endothelial cells. Biochemical studies on purified nuclear fractions also demonstrated the presence of phosphoglycerate mutase activity in the nucleus. Both immunocytochemical and biochemical techniques showed that nuclear phosphoglycerate mutase-specific activity depended on the type of cell.     

Location of phosphoglycerate mutase in rat skeletal muscle. An immunocytochemical and biochemical study

The subcellular distribution of phosphoglycerate mutase was studied by immunogold techniques. With the aid of highly affinity-purified anti-phosphoglycerate mutase antibodies, the enzyme was found in both cytosol and nucleus of rat skeletal muscle. No evidence of interaction with contractile proteins was observed in cytosol. Nuclear location was also confirmed biochemically using purified nuclear preparations from rat skeletal muscle. Only one immunoreactive nuclear band was observed by Western blot experiments and corresponded to that of phosphoglycerate mutase mobility. Activity measurements from nuclear extracts showed that 25% of total specific activity is found in the nuclei.     

Horizontal gene transfer from a flowering plant to the insular pine Pinus canariensis (Chr. Sm. Ex DC in Buch)

Horizontal gene transfer (HGT) is viewed as very common in the plant mitochondrial (mt) genome, but, to date, only one case of HGT has been found in gymnosperms. Here we report a new case of HGT, in which a mt nad5-1 fragment was transferred from an angiosperm to Pinus canariensis. Quantitative assay and sequence analyses showed that the foreign nad5-1 is located in the mt genome of P. canariensis and is nonfunctional. An extensive survey in the genus Pinus revealed that the angiosperm-derived nad5-1 is restricted to P. canariensis and present across the species'' range. Molecular dating based on chloroplast DNA suggested that the HGT event occurred in the late Miocene after P. canariensis split from its closest relatives, and that the foreign copy became fixed in P. canariensis owing to drift during its colonization of the Canary Islands. The mechanism of this HGT is unclear but it was probably achieved through either direct cell–cell contact or external vectors. Our discovery provides evidence for an important role of HGT in plant mt genome evolution.     

Intraspecific variation and plasticity in growth and foliar morphology along a climate gradient in the Canary Island pine

Foliar plasticity in response to ontogeny, location within the plant and environmental changes is widespread among long-lived organisms. To quantify the phenotypic variation in needle morphology and anatomy in response to a climate gradient, we compared contrasted populations of Pinus canariensis grown in five sites inside and outside the natural distribution area of the species. Most needle and growth traits were strongly affected by site. In general, site xericity increased the relative area of the dermal and transfusion tissues and decreased mesophyll and endodermis. Within each site, provenances from less productive locations tended to show longer needles, less relative area of dermal tissues but higher relative area of mesophyll and transfusion tissue than provenances from fertile origins. Although sclerophylly increased with aridity, no genetic differences were found for this trait thus apparently the ontogenetic delay of some provenances in xeric environments was not related with the formation of tougher needles. Several patterns of phenotypic response to different environments were shown. In general, all traits were plastic but the degree of plasticity was higher in traits related with growth than foliar traits. These results, combined with formerly published research, suggest that highly plastic populations rather than narrowly specialized ones have been selected in this species to cope with the complex interaction of environmental factors in its habitat.     

Characterization of breast cancer by array comparative genomic hybridization.

Cancer progression is due to the accumulation of recurrent genomic alterations that induce growth advantage and clonal expansion. Most of these genomic changes can be detected using the array comparative genomic hybridization (CGH) technique. The accurate classification of these genomic alterations is expected to have an important impact on translational and basic research. Here we review recent advances in CGH technology used in the characterization of different features of breast cancer. First, we present bioinformatics methods that have been developed for the analysis of CGH arrays; next, we discuss the use of array CGH technology to classify tumor stages and to identify and stratify subgroups of patients with different prognoses and clinical behaviors. We finish our review with a discussion of how CGH arrays are being used to identify oncogenes, tumor suppressor genes, and breast cancer susceptibility genes.     

Isolation and sequencing of a cDNA encoding the B isozyme of rat phosphoglycerate mutase.

Phosphoglycerate mutase consists of two kinds of different subunits, M and B. We previously sequenced a rat cDNA encoding the type-M subunit. Here, we report the sequence of the type-B subunit-encoding cDNA. This cDNA has 1754 bp and contains a long 3'-untranslated region of 897 bp.     

Macromastia: how much of it is fat?

A total of 25 patients who underwent bilateral breast reduction were included in this study. Each patient's age, weight, height, and amount of breast tissue removed from each breast were recorded. The body mass index was calculated for each patient. On the day of the operation, tissue samples (two each) were taken from the central, lateral, and preaxillary areas of the breast. One of the samples was weighed, placed in a closed glass container, and heated for 10 minutes in a microwave oven at full power. The liquid fat was separated from the solid residue, and the percentage of fat was calculated. The other sample from each area was examined grossly, and representative sections, corresponding to the distribution of fat and connective tissue, were submitted for evaluation. In these samples, the percentage of fat, gland, and connective tissue was estimated using low-magnification light microscopy. In this group of patients (who had an average age of 34 years and who were significantly overweight as determined by a mean body mass index of 28), it was found (using the microwave method) that there was a mean fat percentage of 61 percent in the central breast area, 74 percent in the lateral breast area, and 73 percent in the preaxillary area. Upon microscopic examination, the pathologist reported that fat accounted for 64 percent of the central breast area, 92 percent of the lateral breast area, and 94 percent of the preaxillary area. On average, the central breast area in macromastia patients had only seven percent gland and 29 percent connective tissue. The lateral and preaxillary areas of the breast had one to three percent gland and five percent connective tissue. The two methods had a significant (p < 0.05) positive correlation in the central breast area, but in the lateral and preaxillary regions, the correlation was poor. In the microscopic examination, there was a tendency to overestimate the amount of fat. Both methods of evaluation used in the study concur that the enlarged breast of macromastia consists primarily of fat and that the glandular element is rather small.