The natural history ofPetrobia (Tetranychina) harti (Ewing) andPetrobia (Mesotetranychus) tunisiae Manson (Acari: Tetranychidae) in the laboratory

Petrobia harti (Ewing) developed more rapidly, deposited more eggs and lived longer onOxalis corniculata than onO. articulata. No development took place on several other recorded host plants. In the field this mite was most abundant during early summer. Males made up less than 10% of the population, and no diapause eggs were seen in the field.Petrobia tunisiae Manson developed on various winter Gramineae, produced about 17 non-diapause eggs during its first generation and mostly diapause eggs in the second. A few diapause eggs kept in the laboratory and dipped in chloroform hatched even after 3 years. A summer diapause is postulated for this species.     

Bulb mite,Rhizoglyphus robini (Astigmata: Acaridae) as an experimental animal

Rhizoglyphus robini Claparède (Acari: Astigmata: Acaridae) is proposed as a model laboratory animal for biological, ecological, physiological and toxicological studies. The mite is easy and inexpensive to rear, quite fecund, convenient to manipulate, and may rapidly be raised to gram quantities. Examples are presented of its use in soil pest ecology and control studies, and in physiological, biochemical and toxicological investigations. Efforts to explore the induction of detoxification systems by various chemicals, and a demonstration of its control by solarization, are also described.     

Serum relaxin levels in prostaglandin E2 induced abortions

Relaxin, a peptide hormone produced only by the corpus luteum of pregnancy, can be used as a marker of luteal function in human pregnancy. Serum immunoreactive relaxin levels were measured serially in six women having second trimester abortions induced with intravaginal prostaglandin E2 (PGE₂) suppositories. All patients aborted within 17 hours of the first suppository. No significant changes were detectable in serum relaxin levels in any of the patients. It is concluded that PGE₂ does not interfere with the corpus luteum's ability to secrete relaxin in the second trimester of human pregnancy.     

Uptake and binding of cadmium and mercury to metallothionein in rat hepatocyte primary cultures

The administration of inorganic Cd and Hg in vivo has been shown to result in markedly different metal concentrations in rat liver. Primary cultures of rat hepatocytes were utilized to gain insight into the dispositional differences between these chemically similar metals. Hepatocyte monolayer cultures were exposed to several concentrations of Cd or Hg (3, 10 and 30μm) in serum-containing medium for 30min. The cells were then washed and incubated in fresh medium for the remainder of the experiment. Hepatocytes exposed to Cd accumulated significantly more metal than hepatocytes exposed to equimolar concentrations of Hg. In cells exposed to 3μm-Cd there was an initial loss of Cd from the hepatocytes when placed in fresh medium, followed by a gradual re-uptake of metal, concomitant with increased binding to metallothionein. In hepatocytes exposed to 3 and 10μm-Cd, 87 and 77% of the intracellular Cd was bound to metallothionein within 24h. Loss of Hg from hepatocytes pulsed with 30μm-Hg was also observed upon the addition of fresh medium and continued for the duration of the experiment. No time-dependent increase in Hg binding to metallothionein was observed. A maximum of about 10% of the intracellular Hg was found associated with metallothionein in hepatocytes exposed to 30μm-Hg. Studies utilizing [³⁵S]cysteine incorporation indicated significant increases in the amount of metallothionein synthesized in hepatocytes exposed to 3 and 10μm-Cd (300% of control value) and 30μm-Hg (150% of control value) 24h after metal pulsing. Time-course studies revealed a 6–12h lag in metallothionein synthesis, followed by a significant elevation in [³⁵S]cysteine incorporation into metallothionein between 12 and 24h. These studies suggest that (a) isolated hepatocytes differentiate between Cd and Hg and preferentially accumulate the former, and (b) Cd strongly stimulates the induction of, and preferentially binds to, metallothionein, whereas Hg induces weakly, and does not preferentially bind to, metallothionein.     

Chronic granulomatous otitis media in bottle-fed Inuit children.

Otitis media in Inuit children is a problem of relatively recent origin and unknown cause. The prevalence of otitis media in 238 Inuit and 47 Caucasian children in Nain, a small community in Labrador, was determined by examination, and the history of breast-feeding or bottle-feeding was obtained. The prevalence of otitis media was found to be inversely related to the age at which bottle-feeding was started. Clinical observations suggest that otitis media in Inuit children is part of a process leading to chronic foreign body granuloma of the middle ear, and that the granuloma is formed from milk introduced into the relatively short and straight eustachian tubes of Inuit infants by the high negative intraoral pressure necessary for bottle-feeding.     

Isolation of super-repressor mutants in the histidine utilization system of Salmonella typhimurium.

Two super-repressor mutations in the histidine utilization (hut) operons of Salmonella typhimurium are described. Cells bearing either of these mutations have levels of hut enzymes that do not increase above the uninduced levels when growth is in the presence of either histidine or the gratuitous inducer imidazole propionate. Both mutations lie in the region of the gene for the hut repressor, hutC, and reverse mutations of both are to the constitutive (repressor-negative) rather than to the inducible (wild type) phenotype. In hybrid merodiploid strains the super-repressor mutations are dominant over either wild-type (hutC+) or repressor-negative (hutC-) alleles. Whereas both super-repressor mutations cause the uninducible synthesis of hut enzymes, the degree of repression is different. One mutation causes repression of enzyme synthesis in one of the two hut operons to a level below the basal, uninduced level of wild-type cells. The other mutation causes repression to a lesser degree than in wild-type cells, so that the hut enzymes are present at a level above the normal basal level; this partially constitutive synthesis is greater for the enzymes of one of the hut operons than for the enzymes of the other. Thus, both mutations apparently result in repressors with altered operator-binding properties, in addition to altered inducer-binding properties.     

A Case of Relapsed Chromoblastomycosis Due to Fonsecaea monophora: Antifungal Susceptibility and Phylogenetic Analysis

Chromoblastomycosis is a chronic cutaneous and subcutaneous mycosis. The management of this infection continues to be challenging because there is no consensus on the therapeutic regimen. We report here a case of a 69-year-old male patient with cauliflower-like lesions on his left leg and foot. He had already been treated with itraconazole at a dose of 200 mg/day for 5 months, with mycological cure for all the affected areas. However, the lesions relapsed at both sites, and treatment with itraconazole was resumed at the dose previously used. Initially, direct mycological examination, cultural, and microculture slide observation were performed. Afterward, sequencing of the ITS1-5.8S rDNA-ITS2 region of the fungal DNA and evaluation of its susceptibility to antifungal agents alone and in combination were performed. In direct mycological examination, the presence of sclerotic cells was verified, and the fungus was identified as Fonsecaea based on cultural and microscopic examinations. Identification as Fonsecaea monophora was confirmed after sequencing of the ITS region and phylogenetic analysis. The isolate was susceptible to itraconazole and terbinafine. The combinations of amphotericin B and terbinafine and terbinafine and voriconazole were synergistic. The use of drugs for which the causative agent is susceptible to singly or in combination may be an alternative for the treatment of mycosis. Furthermore, the identification of the agent by molecular techniques is important for epidemiological purposes. To the best of our knowledge, this is the first case of relapsed chromoblastomycosis caused by F. monophora in Brazil.     

Seasonal response of fish assemblages to habitat fragmentation caused by an impoundment in a Neotropical river

Changes in fish assemblages between the zones above and below Funil dam in Southeastern Brazil were investigated to evaluate the possible impacts of this impoundment in two contrasting seasons: summer/wet and winter/dry. We expect differences in fish assemblage structure and in environmental conditions between seasons and between the reservoir and the zone downriver of the dam. A total of 3,579 individuals comprising 38 species, including six non-natives, were collected. As expected, the comparatively high habitat complexity and water flow regime of the downriver zone favored a richer and more abundant fish assemblage compared with the reservoir, especially in the wet season. In this period, water covers part of the riparian vegetation, increasing habitat availability and nutrient input. Additionally, the dam prevents upriver migration of rheophilics fish species such as the Characiformes Prochilodus lineatus and Leporinus copelandii, and the Siluriformes Pimelodus fur and Pimelodus maculatus, thus increasing shoals below the dam. Although the reservoir represents a simplified ecosystem highly influenced by non-native top predator species (e.g. the Perciformes Cichla kelberi and Plagioscion squamosissimus), seasonal processes (e.g. water level fluctuations and flood pulses) seem to play a role in structuring of the fish assemblage. Environmental variables, mainly turbidity, temperature, and conductivity were significantly associated to spatial-temporal patterns of fish assemblage. In this freshwater tropical reservoir, the spatial scale, rather than the seasonal changes in environmental variables, was the dominant factor structuring fish assemblage in the reservoir and in the zone downriver of the dam.     

Protein complexes associated with β-catenin differentially influence the differentiation profile of neonatal and adult CD8+ T cells

The canonical Wnt signaling pathway is a master cell regulator involved in CD8⁺ T cell proliferation and differentiation. In human CD8⁺ T cells, this pathway induces differentiation into memory cells or a “stem cell memory like” population, which is preferentially present in cord blood. To better understand the role of canonical Wnt signals in neonatal or adult blood, we compared the proteins associated with β-catenin, in nonstimulated and Wnt3a-stimulated human neonatal and adult naive CD8⁺ T cells. Differentially recruited proteins established different complexes in adult and neonatal cells. In the former, β-catenin-associated proteins were linked to cell signaling and immunological functions, whereas those of neonates were linked to proliferation and metabolism. Wnt3a stimulation led to the recruitment and overexpression of Wnt11 in adult cells and Wnt5a in neonatal cells, suggesting a differential connexion with planar polarity and Wnt/Ca²⁺ noncanonical pathways, respectively. The chromatin immunoprecipitation polymerase chain reaction β-catenin was recruited to a higher level on the promoters of cell renewal genes in neonatal cells and of differentiation genes in those of adults. We found a preferential association of β-catenin with CBP in neonatal cells and with p300 in the adult samples, which could be involved in a higher self-renewal capacity of the neonatal cells and memory commitment in those of adults. Altogether, our results show that different proteins associated with β-catenin during Wnt3a activation mediate a differential response of neonatal and adult human CD8⁺ T cells.