Soil transmitted helminth (STH) infections in an indigenous community in Ortigueira,Paraná, Brazil and relationship with its nutritional status

Within the frame of World Health Organisation (WHO) guidelines for the control of soil transmitted helminth (STH) infections, a baseline survey has been conducted in Queimadas Indian schoolchildren (group A) as compared with urban schoolchildren (group B), both located in Ortigueira, Paraná, Brazil, with the aim of orientating investigations. In an opportunistic study, the possible relationship between STH infection and nutritional status has been investigated. A total of 236 schoolchildren aged 5-15 years were enrolled, 100 in group A and 136 in group B. Prevalence of STH infections and heavy intensity infections were significantly higher in the group A (P < .001). A statistical significant correlation between stunting (Z-score < -2) and intensity of STH infections was noted. These results strongly suggested that mass treatment would be indicated in the indigenous community, possibly leading to improved nutritional status.     

Genetic differentiation,gene flow and the origin of infestations of the medfly,Ceratitis capitata

The genetic structure of natural populations of the economically important dipteran species Ceratitis capitatawas analysed using both biochemical and molecular markers. This revealed considerable genetic variation in populations from different geographic regions. The nature of this variation suggests that the evolutionary history of the species involved the spread of individuals from the ancestral African populations through Europe and, more recently, to Latin America, Hawaii and Australia. The observed variation can be explained by various evolutionary forces acting differentially in the different geographic areas, including genetic drift, bottleneck effects, selection and gene flow. The analysis of the intrinsic variability of the medfly's genome and the genetic relationships among populations of this pest is a prerequisite for any control programme.     

The role of interleukin-1 in interactive senescence and age-related human endometrial cancer

The causes of the age-related increase in cancer rates are poorly understood. One cause could be age-related changes in the stromal/epithelial cell interactions that facilitate tumorigenesis. We tested the hypothesis that aging of human endometrial stromal fibroblasts (ESF) alters their influence over endometrial epithelial cells. ESF from adults were found to inhibit anchorage-independent proliferation, to restrain colony outgrowth, and to induce formation of normal tissue architecture by human endometrial cancer cells. As ESF age, these inhibitory influences on malignant-like behaviors by epithelial cells are altered, becoming stimulatory. Age-related change in interleukin-1alpha (IL-1alpha) expression is a molecular determinant of ESF/epithelial cell interactions. Levels of IL-1alpha and IL-1-induced mRNAs increase in ESF with age. Treatment with IL-1 accelerates age-related changes in mRNA abundance and loss of ESF restraint over malignancy-associated behaviors by epithelial cells. Transfection of ESF with the intracellular IL-1 receptor antagonist preserved the young phenotype with respect to interactions with epithelial cells and prevented age-associated increases in groalpha and IL-8 mRNA levels. Our results indicate that aging of ESF is accompanied by an interactive senescence that alters ESF signaling to cancer cells and could contribute to increased cancer rates by providing a microenvironment that is more conducive to tumorigenesis.     

Monodominance in an African Rain Forest: Is Reduced Herbivory Important?1

Tropical monodominant forests in which one tree species dominates the canopy occur in all three major tropical regions, but few studies have focused on the mechanisms responsible for dominance. This study tests the hypothesis that relative to other species in the community, dominant species are well defended and escape herbivore and pathogen damage. We surveyed the rate of damage on young expanding leaves of seedlings and saplings belonging to eight species within both monodominant Gilbertiodendron dewevrei forests and adjacent mixed–species forests in eastern Congo. Results showed that escape from herbivore and pathogen damage is not a mechanism by which Gilbertiodendron achieves dominance, as it suffered the highest damage level of any species surveyed. Similarly, other sub–dominant common species also suffered high rates of damage. These results are discussed in relation to the phenolic, fiber, and nitrogen content of leaves, and in the context of current theories pertaining to plant–herbivore interactions.     

Tumor necrosis factor inhibits human myogenesis in vitro.

We examined the effects of human recombinant tumor necrosis factor-alpha (TNF) on human primary myoblasts. When added to proliferating myoblasts, TNF inhibited the expression of alpha-cardiac actin, a muscle-specific gene whose expression is observed at low levels in human myoblasts. TNF also inhibited muscle differentiation as measured by several parameters, including cell fusion and the expression of other muscle-specific genes, such as alpha-skeletal actin and myosin heavy chain. Muscle cells were sensitive to TNF in a narrow temporal window of differentiation. Northern (RNA) blot and immunofluorescence analyses revealed that human muscle gene expression became unresponsive to TNF coincident with myoblast differentiation. When TNF was added to differentiated myotubes, there was no effect on muscle gene expression. In contrast, TNF-inducible mRNAs such as interferon beta-2 still responded, suggesting that the signal mediated by TNF binding to its receptor had no effect on muscle-specific genes after differentiation.     

Membrane-associated binding sites for indoleacetic acid in the rice coleoptile

As described previously, the sensitivity of rice (Oryza sativa L.) coleoptiles to auxin is modulated by oxygen. Under anoxia, coleoptile elongation is insensitive to exogenously applied indole-3-acetic acid (IAA), whereas its sensitivity increases in air in the presence of the exogenous stimulus. Here we report the presence of two independent classes of membrane-bound IAA-binding sites in air-grown coleoptiles. Their binding activity is strictly correlated with the system's sensitivity to IAA. We designate them as site A (high affinity) and site B (low affinity). Site A shows a relatively fast response to anoxia, and is highly specific for auxins. Regulation of site-A binding activity through ATP, whose availability decreases under anoxia, is postulated. A role as auxin carrier is suggested for site B.Abbreviations ABS(s) auxin-binding site(s) - IAA indole-3-acctic acid - NAA 2-naphthaleneacetic acid - ION3 valinomycin, nigericin, carbonylcyanide p-trifluoromethoxyphenyl hydrazone Dedicated to the memory of Professor G. Torti, who passed away on 2 May, 1988     

Genetic characterization of aggregation-defective developmental mutants of Myxococcus xanthus.

The transposon Tn5 was used to map temperature-sensitive mutants of Myxococcus xanthus defective in aggregation (C. E. Morrison and D. R. Zusman, J. Bacteriol. 140:1036-1042, 1979). Seven of the eight mutants showing a similar terminal phenotype (rough) were found to be tightly linked. These mapped in a group of loci which we have designated aggR1, aggR2, aggR3, and aggR4. Temperature-sensitive mutants having a different terminal phenotype were not liked to aggR. A search through a group of nonconditional rough mutants indicated that a much lower proportion of these (1 of 35) mapped in aggR. Thus, aggR is probably only one of many sites which can lead to the rough phenotype when mutated. Localized mutagenesis was used to isolate nine additional aggR mutants. All mapped within aggR1, aggR2, or aggR3, and none was found outside this region. Thus, we have characterized a cluster of developmental genes which are needed for aggregation in M. xanthus. The localization of a Tn5 insert adjacent to this region makes possible further manipulation of these genes.     

Tumor necrosis factor-alpha and interleukin 1-alpha regulate transferrin receptor in human diploid fibroblasts. Relationship to the induction of ferritin heavy chain

We have studied transferrin receptor expression in MRC5 human fibroblasts in response to tumor necrosis factor-alpha (TNF, cachectin) or interleukin 1-alpha (IL-1). Treatment of exponentially growing MRC5 cells with these cytokines led to a 3-4-fold increase in transferrin receptor mRNA and a coordinate increase in transferrin receptor protein by 24 h. Under these conditions, stimulation of [3H]thymidine incorporation was minimal, suggesting that the induction of transferrin receptor by TNF and IL-1 is mediated by a growth-independent regulatory mechanism. A study of the time course of this response showed that cytokine-mediated increases in transferrin receptor mRNA and protein proceeded after a lag of 12-24 h. A simultaneous analysis of the effects of TNF and IL-1 on ferritin in MRC5 cells was also performed. Ferritin L mRNA levels were unchanged. However, induction of ferritin H mRNA was seen within 4 h, preceding the induction of the transferrin receptor. The synthesis of ferritin H (but not ferritin L) protein peaked at 8 h after TNF or IL-1 treatment, followed by a rapid decrease in both ferritin H and L protein synthesis. As ferritin H synthesis declined, levels of transferrin receptor protein increased, reaching a maximum by 24 h. These results suggest that the cytokine-dependent induction of ferritin H and subsequent increase in the transferrin receptor are related and possibly interdependent events. This study demonstrates that the complex role of TNF and IL-1 in iron homeostasis includes modulation of the transferrin receptor.     

Murine ferritin heavy chain: isolation and characterization of a functional gene

A mouse liver genomic library screened with a full-length cDNA encoding murine ferritin heavy chain (mFHC) [Torti et al., J. Biol. Chem. 263 (1988) 12638-12644] yielded a functional genomic clone mFHC. The genomic clone isolated included a region of approximately 3 kb containing four exons and three introns. Sequence comparisons of the mouse genomic clone with other genomic clones from rat, human and chicken showed a high degree of similarity among species in the coding regions. Introns and flanking sequences were less conserved. However, comparison of mFHC promoter elements with FHC genes from other species revealed common elements. Analysis of the genomic structure of FHC suggested the presence of pseudogenes. S1 nuclease analysis, however, confirmed that this mouse clone, when transfected into human MRC-5 fibroblasts, was transcribed, indicating that this clone contains an FHC functional gene.