Structure and development of the metapleural gland in Technomyrmex vitiensis

Insectes Sociaux - We studied the internal and external appearance of the metapleural gland in the five castes of Technomyrmex vitiensis. All castes do possess the gland, but with a clear gradient...     

The amino-acid sequence of troponin C from frog skeletal muscle.

The primary structure of the troponin C from skeletal muscle of the frog Rana esculenta has been determined. The amino acid sequence was deduced from amino acid determinations of peptides obtained after cleavage with cyanogen bromide. Overlapping peptides were isolated from tryptic digests of performic-acid-oxidized troponin C and phthalylated performic-acid-oxidized troponin C. All overlaps have been determined except for the Arg-Ile sequence at position 103--104, which has been obtained by comparison with homologous troponins C. Frog troponin C consists of one polypeptide chain containing 152 amino acids. The calculated molecular weight is 18299. There is a single cysteine residue at position 101 and a single tyrosine residue at position 112. No histidine or tryptophan residues are present. The amino-terminal amino acid is N-acetylated. The homology of frog troponin C with other skeletal and cardiac troponin C is briefly discussed.     

Indapamide-induced prevention of myocardial fibrosis in spontaneous hypertension rats is not nitric oxide-related

We studied the effect of thiazide-like diuretic--indapamide on fibrosis development in the left ventricle of young spontaneously hypertensive rats (SHR) and assessed the involvement of nitric oxide in this process. Six-week-old male SHR were treated with indapamide (1 mg/kg/day) for six weeks. Age-matched SHR were used as hypertensive and Wistar-Kyoto rats (WKY) as normotensive control. Systolic blood pressure was measured by tail-cuff plethysmography. Nitric oxide synthase (NOS) activity, protein expressions of endothelial (eNOS) and inducible NOS (iNOS), myocardial fibrosis and collagen type I and III were determined in the left ventricle. Indapamide treatment partially prevented SBP increase in SHR (SHR+Indapamide: 157+/-4, SHR: 171+/-3, WKY: 119+/-3 mmHg). Indapamide prevented myocardial fibrosis development in SHR, but without affecting collagen type I to type III ratio. Indapamide did not affect NOS activity as well as eNOS and iNOS protein expressions in the left ventricles evaluated by both Western blot and immunohistochemically. In conclusion, our results indicate that indapamide-induced prevention of myocardial fibrosis is not mediated by nitric oxide-related mechanism.     

Connective tissue growth factor (CTGF) stimulates vascular smooth muscle cell growth and migration in vitro

Connective tissue growth factor (CTGF) was first identified as a 38-kDa cysteine-rich protein which can be specifically induced by TGF-beta and was recently found to be expressed abundantly in atherosclerotic lesions, but only marginally in normal vascular tissues. It was hypothesized that CTGF is one of the factors involved in the development of atherosclerotic lesions. In this study, we investigated the functions of CTGF protein in regulating the growth and migration of vascular smooth muscle cells (VSMC) and found that by overexpressing CTGF in VSMC, proliferation and migration rates were significantly increased. The accelerated growth and migration can be reversed by an anti-CTGF antibody. In addition, overexpression of CTGF also promotes VSMC to express more extracellular matrix protein collagen I and fibronectin. Our results indicate that CTGF is a growth factor for VSMC and it may play a similar role in promoting VSMC proliferation, migration, and formation of extracellular matrix, in vivo.     

Rac GTPase isoform-specific regulation of NADPH oxidase and chemotaxis in murine neutrophils in vivo. Role of the C-terminal polybasic domain

The Rho family GTPase Rac acts as a molecular switch for signal transduction to regulate various cellular functions. Mice deficient in the hematopoietic-specific Rac2 isoform exhibit agonist-specific defects in neutrophil chemotaxis and superoxide production, despite expression of the highly homologous Rac1 isoform. To examine whether functional defects in rac2(-/-) neutrophils reflect effects of an overall decrease in total cellular Rac or an isoform-specific role for Rac2, retroviral vectors were used to express exogenous Rac1 or Rac2 at levels similar to endogenous. In rac2(-/-) neutrophils differentiated from transduced myeloid progenitors in vitro, increasing cellular Rac levels by expression of either exogenous Rac1 or Rac2 increased formylmethionylleucylphenylalanine- or phorbol ester-stimulated NADPH oxidase activity. Of note, placement of an epitope tag on the N terminus of Rac1 or Rac2 blunted reconstitution of responses in rac2(-/-) neutrophils. In rac2(-/-) neutrophils isolated from mice transplanted with Rac-transduced bone marrow cells, superoxide production and chemotaxis were fully reconstituted by expression of exogenous Rac2, but not Rac1. A chimeric Rac1 protein in which the Rac1 C-terminal polybasic domain, which contains six lysines or arginines, was replaced with that of the human Rac2 polybasic domain containing only three basic residues, also reconstituted superoxide production and chemotaxis, whereas expression of a Rac2 derivative in which the polybasic domain was replaced with that of Rac1 did not and resulted in disoriented cell motility. Thus, the composition of the polybasic domain is sufficient for determining Rac isoform specificity in the production of superoxide and chemotaxis in murine neutrophils in vivo.     

Haptoglobin and CCR2 receptor expression in ovarian cancer cells that were exposed to ascitic fluid: Exploring a new role of haptoglobin in the tumoral microenvironment

Haptoglobin (Hp) is an acute-phase protein that is produced by the liver to capture the iron that is present in the blood circulation, thus avoiding its accumulation in the blood. Moreover, Hp has been detected in a wide variety of tissues, in which it performs various functions. In addition, this protein is considered a potential biomarker in many diseases, such as cancer, including ovarian carcinoma; however, its participation in the cancerous processes has not yet been determined. The objective of this work was to demonstrate the expression of Hp and its receptor CCR2 in the ovarian cancer cells and its possible involvement in the process of cell migration through changes in the rearrangement of the actin cytoskeleton using western blot and wound-healing assays and confirming by confocal microscopy. Ovarian cancer cells express both Hp and its receptor CCR2 but only after exposure to ascitic fluid, inducing moderated cell migration. However, when the cells are exposed to exogenous Hp, the expression of CCR2 is induced together with drastic changes in the actin cytoskeleton rearrangement. At the same time, Hp induced cell migration in a much more efficient manner than did ascitic fluid. These effects were blocked when the CCR2 synthetic antagonist RS102895 was used to pretreat the cells. These results suggest that Hp-induced changes in the cell morphology, actin cytoskeleton structure, and migration ability of tumor cells, is possibly “preparing” these cells for the potential induction of the metastatic phenotype.     

Heptachlor and o‐p′DDT effects on protein kinase activities associated with human placenta particulate fractions

Organochlorine pesticides have been detected in placenta. The ability of heptachlor (HC) and 1,1,1‐tricholoro‐2‐(2‐chlorophenyl)‐2‐4‐chlorophenyl)ethane (o‐p′DDT) to interfere with protein phosphorylation was evaluated. In vitro incubations of cell‐free placental villi homogenates with a concentration range 1–100 µM were performed. In particulate fractions, total serine/threonine kinase activity was increased by 10 µM HC and o‐p′ DDT (59% and 82%, respectively). Maximum eightfold increase was observed with 10 µM o‐p′ DDT on protein kinase A activity. By contrast, protein kinase C activity was reduced by 10 µM HC and o‐p′ DDT (40% and 52%, respectively). Endogenous substrate phosphorylation studies demonstrated that slight but significant increase in 24‐kDa band labeling was produced in nuclear samples with 1, 10, and 100 µM HC and 100 µM o‐p′ DDT. Exposition to 100 µM HC increased 85‐kDa band labeling. In mitochondrial fractions, 10 µM HC and o‐p′ DDT increased 24‐ and 65‐kDa bands' labeling. These data indicate that both pesticides affect protein kinase activities in particulate fraction. Nuclear compartmentalization of these compounds, insertion in membranes, and chemical stress production may be associated to the observed effects, thus suggesting deleterious consequences in signaling pathways. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:185–192, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20277     

Annual follow-up of the gastrointestinal parasitosis of white-tailed deer Odocoileus virginianus (Artiodactyla: Cervidae) in captivity in Yucatán, México]

Gastrointestinal parasites, and egg and oocyst output in the faeces of captive white-tailed deer (Odocoileus virginianus yucatanensis) were recorded in Yucatan, Mexico. Feces were obtained from from January through December 1995 (ten samples every two weeks per place). Samples were processed by flotation and the McMaster techniques. Faecal cultures for L3 larvae were made by the Corticelli-Lai technique. Oocysts in faeces were cultured in 2% potassium dicromate. Seven genera were determined (Haemonchus spp., Cooperia spp, Isospora spp., Eimeria spp., Trichuris spp., Strongyloides spp. and Moniezia spp.) which represent five orders. The most frequent genera were Haemonchus, Isospora and Eimeria. The genus Isospora is reported for the first time in deer of this region, although it was not possible to explain the source of this parasite. The frequency and level of faecal egg and oocyst outputs were variable during the year and increased during the rainy season. There was a positive correlation between relative humidity, environmental temperature and rainfall with the coccidia and strongylida orders. In the central zone of Yucatan the meteorological conditions during the rainy season are favourable for the development of gastrointestinal parasitism which enable an increased risk of infection for deer.