A new species of Trichostrongylus (Nematoda, Trichostronglyoidea) parasitizing the subterranean rodent Ctenomys talarum (Rodentia, Octodontidae) from Mar de Cobo, Argentina

A new nematode species, Trichostrongylus duretteae sp. nov., found in the small intestine of Ctenomys talarum from Argentina is described. The new species more closely resembles T. suis lwanitsky, 1930 a parasite of Sus scrofa in the USSR. However, the new species can be distinguished by the morphology of male genital bursa: Rays 6 distant from rays 8 and a larger dorsal ray in relation to the length of rays 2 to 8. The present finding is the first record of the genus Trichostronglyus in rodents of the family Octodontidae.     

Ontogeny of spatial working memory in the subterranean rodent ctenomys talarum

While several works analyzed the spatial learning and memory capacities in adults of subterranean rodents, no study was done examining the development of these cognitive processes in pups of any of those species. Therefore, the development of spatial working memory in the South American subterranean rodent Ctenomys talarum was investigated by analyzing the pups' spatial performance in a delayed alternation task. When a short delay of 1 min was interposed between runs in the Y‐maze, 20‐day‐old pups made more errors than 40‐ and 60‐day‐old pups. When longer intervals (10 min) were elapsed between runs, younger pups made approximately twice as many errors as the ones committed by 60‐day‐old pups, showing the age‐dependent development of spatial working memory in this species of subterranean rodent. Increased space use by C. talarum pups, caused first by the appearance of independent exploratory behavior and later by the need of leaving maternal territory and construct a new burrow system, showed some correspondence with the improvements in the pups' spatial working memory performance, suggesting for the importance of this cognitive capacity in developing pups for which spatial learning and memory constitute essential abilities for survival and fitness. Dev. Psychobiol. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 592–597, 2010.     

Genotoxicity biomonitoring in regions exposed to vehicle emissions using the comet assay and the micronucleus test in native rodent Ctenomys minutus

Exposure to motor vehicle emissions represents an important concern for possible long-term health effects. The present report describes: 1) the application and verification of the alkaline comet assay in Ctenomys minutus to detect the possible genotoxicity of automobile emissions; 2) a comparison of the comet assay results with peripheral blood micronucleus (MN) assay results performed in the same animals; and 3) the identification of agents involved in the responses and in the seasonal variation of the effects. Ctenomys minutus (Octodontidae-Rodentia) were captured in two different fields from both sides of RS/030, a highway on the coastal plain of the Brazilian state of Rio Grande do Sul. Reference animals were obtained from a nearby field that was about 3 km distant from any road. By the end of this study, 123 rodents (73 females and 50 males) were live-trapped. Our results indicate that there was an increase in cells with DNA damage for C. minutus environmentally exposed to automobile emissions, as demonstrated by the alkaline comet assay, but there was no increase in micronucleated cells. The alkaline comet assay showed age and gender differences in the response. The comet assay results suggest that adult females are the principal population affected by air pollutants from vehicle emissions. Chemical data were also collected from areas exposed to automobile exhaust and these indicated that elevated levels of hydrocarbons, metals, and NO(2) were associated with the elevated levels of damaged cells observed in the wild rodent C. minutus. Our results agree with previous data on engine and fuel components, where weak increases in damage for native rodents exposed to emissions have been observed. Other larger, controlled studies are needed to better understand how the metabolism of C. minutus affects its response to emission exposure.     

Proopiomelanocortin in the arcuate nucleus of the rodent Meriones shawi: Effects of dehydration

Proopiomelanocortin (POMC) is a 36 kDa glycoprotein implicated in homeostatic balance. We used in situ hybridization histochemistry coupled with quantitative autoradiography to determine the anatomical distribution of POMC mRNA-expressing neurons in the arcuate nucleus (AN) and to examine the effects of prolonged dehydration on POMC gene expression in a semi-desert rodent, Meriones shawi (Shaw’s Jird). In the hypothalamus of control animals, POMC mRNA-expressing neurons were exclusively localized in the AN and they showed a differential distribution and density along its rostro-caudal subdivisions. In dehydrated animals, water deprivation caused a decrease in POMC mRNA labeling in the AN. These results suggest that dehydration stress can induce negative regulation of POMC gene expression in this species. A comparative study of weight variation between control and dehydrated animals showed a weight loss followed by stabilization of weight during prolonged dehydration.     

Thermoregulatory responses of firemen to exercise in the heat

Summary Twelve volunteer (VF) and 12 professional firemen (PF) wearing only brief trunks exercised on an electrically-braked cycle ergometer at three-five exercise intensities. After 45 min of exercise at 75 W, the exercise intensity was elevated in steps of 25 W every 15 min until the subject was exhausted. Air temperature was regulated to equal skin temperature (36°–38°C) and relative humidity was regulated at 52%. The two groups of firemen were comparable in terms of body mass, age and maximum oxygen consumption. Their oxygen consumption, rectal and skin temperatures, sweating and heart rate were measured during the tests. Blood lactate concentration was measured before, during and after the test. The physiological strain was higher in VF as indicated by higher heat storage, heart rate, skin and rectal temperatures. Sweat rate tended to be lower in VF than PF. The results indicated a better adaptation of the professional compared to the volunteer firemen to work in the heat, although the degree of heat acclimatization was considered to be equally minimal in both groups.     

The cost of a specific immune response in young guinea pigs

The specific immune system is a protective mechanism that detects infection and fights it by production of antibodies. Newborns are especially susceptible to infections because their immune system is not yet as fully developed as that of adults. This has been well established in altricial mammals. Fighting infection is associated with costs (metabolic rate, protein synthesis) potentially affecting other developmental processes. We investigated the specific immune response in a precocial mammal, by testing the response of 3 and 7 day old young guinea pigs (Cavia aperea f. porcellus) against a non-pathogenic antigen (KLH) and determined the effect of the immune response on growth and metabolic rate. Challenged young produced a substantial specific immune response (IgG). The efficiency of the immune response was almost identical in 3 and 7 day old young, but lower than in adult females. Antibody titres achieved by actively immunised young pups were as high as titres transferred transplacentally by mothers immunised on day 40 and 47 of pregnancy. In comparison to a control group, the immune response did not influence growth and metabolic rate measured on day 4 after each immune challenge and was not reflected by changes in hematocrit value. We discuss whether the weaker immune response of pups is caused by reduced allocation of limited resources in growing young or by the immature immune system of young animals.     

Expression of Dpp6 in mouse embryonic craniofacial development

Dipeptidyl-peptidase-like protein 6 (DPP6), a member of the dipeptidyl aminopeptidase family, plays distinct roles in brain development, but its expression in embryonic craniofacial development is unknown. The expression pattern of Dpp6 in the maxillofacial region during mouse embryonic craniofacial development was analyzed by whole-mount in situ hybridization on sections and by real-time PCR analysis. Dpp6 expression was detected during mouse embryonic craniofacial development in embryos 11-13.5 days post-coitum (dpc). Real-time PCR showed high Dpp6 expression present in 11.5-13.5 dpc, and this then decreased as development of maxillofacial region progressed. The expression pattern of Dpp6 suggests that Dpp6 may be involved in embryonic craniofacial development.     

Age-dependent association of mannose-binding lectin polymorphisms with the development of pulmonary tuberculosis in Viet Nam

Mannose-binding lectin (MBL) binds to pathogens and induces complement-mediated opsonophagocytosis. Although the association between MBL2 polymorphisms and tuberculosis (TB) has been studied in various populations, the results are controversial. We explored the stages of TB associated with MBL2 polymorphisms. X/Y (rs7096206) and A/B (rs1800450) were genotyped in 765 new patients with active pulmonary TB without HIV infection and 556 controls in Hanoi, Viet Nam. The MBL2 nucleotide sequences were further analyzed, and plasma MBL levels were measured in 109 apparently healthy healthcare workers and 65 patients with TB. Latent TB infection (LTBI) was detected by interferon-gamma release assay (IGRA). The YA/YA diplotype, which exhibited high plasma MBL levels, was associated with protection against active TB in younger patients (mean age = 32) ≦ 45 years old (odds ratio, 0.61; 95% confidence interval, 0.46–0.80). The resistant diplotype was less frequently found in the younger patients at diagnosis (P = 0.0021). MBL2 diplotype frequencies and plasma MBL levels were not significantly different between the IGRA-positive and -negative groups. MBL2 YA/YA exhibited a protective role against the development of TB in younger patients, whereas the MBL2 genotype and MBL levels were not associated with LTBI. High MBL levels may protect against the early development of pulmonary TB after infection.     

Expression of myogenic regulatory factors in chicken embryos during somite and limb development

The expression of the myogenic regulatory factors (MRFs), Myf5, MyoD, myogenin (Mgn) and MRF4 have been analysed during the development of chicken embryo somites and limbs. In somites, Myf5 is expressed first in somites and paraxial mesoderm at HH stage 9 followed by MyoD at HH stage 12, and Mgn and MRF4 at HH stage 14. In older somites, Myf5 and MyoD are also expressed in the ventrally extending myotome prior to Mgn and MRF4 expression. In limb muscles a similar temporal sequence is observed with Myf5 expression detected first in forelimbs at HH stage 22, MyoD at HH stage 23, Mgn at HH stage 24 and MRF4 at HH stage 30. This report describes the precise time of onset of expression of each MRF in somites and limbs during chicken embryo development, and provides a detailed comparative timeline of MRF expression in different embryonic muscle groups.     

Circadian rhythm of locomotor activity in the four-striped field mouse, Rhabdomys pumilio: a diurnal African rodent

Although humans are diurnal in behaviour, animal models used for the study of circadian rhythms are mainly restricted to nocturnal rodents. This study focussed on the circadian behaviour of a rodent from South Africa that has a preference for daylight, the four-striped field mouse, Rhabdomys pumilio. In order to characterise the behavioural pattern of daily activity, locomotor rhythms were studied under different light regimes using an automated data recording system. Under conditions of natural daylight, which include dawn and dusk transitions, R. pumilio exhibited activity restricted to the daytime period. Activity was concentrated around morning and evening with a decrease during mid-day. A similar diurnal preference pattern of behaviour was recorded under a light-dark cycle of artificial illumination. Under conditions of constant darkness, the four-striped field mouse exhibited a free-running circadian rhythm of locomotor activity with activity concentrated during the subjective day. Free-running rhythms varied greatly between individuals, from slightly less to slightly more than 24 h (range = 23.10 to 24.80 h). Under conditions of constant light, the mice were more active during subjective day, but the free-running rhythm in all individuals was consistently longer than 24 h (range = 24.30 to 24.79 h).     

Circadian rhythms of locomotor activity in the subterranean Mashona mole rat, Cryptomys darlingi

The Mashona mole rat, Cryptomys darlingi, is a social, subterranean African rodent that is rarely, if ever, exposed to light, and that exhibits a regressed visual system. This study investigated locomotor activity patterns of Mashona mole rats (n=12) under different light cycles. Activity was measured using either infrared captors (n=8) or running wheels (n=4). The mole rats entrained their activity to a standard (LD 12:12) photoperiod. They displayed either a nocturnal or diurnal activity preference with one bout of activity and one bout of rest. Therefore, as a species, the Mashona mole rat did not show a clear nocturnal or diurnal activity preference. When the LD (12:12) light cycle was inversed, the animals switched their activity, too. Under constant dark (DD), most mole rats (73%) showed a free-running circadian activity rhythm, but under constant light (LL), only some (36%) did. The free-run period of the rhythm (tau) ranged from 23.83 to 24.10 h. The remaining animals were arrhythmic. There was large interindividual and intraindividual variations in the rate and extent of entrainment, time of activity preference, and activity patterns. Possible reasons for the observed variations are discussed. It is concluded that the Mashona mole rat has an endogenous activity rhythm which approximates 24 h, that the mole rat can distinguish between light and dark, and that the endogenous clock utilises this photic information as a zeitgeber.     

Characterization of a t(5;8)(q31;q21) translocation in a patient with mental retardation and congenital heart disease: implications for involvement of RUNX1T1 in human brain and heart development

The chromosome break points of the t(8;21)(q21.3;q22.12) translocation associated with acute myeloid leukemia disrupt the RUNX1 gene (also known as AML1) and the RUNX1T1 gene (also known as CBFA2T3, MTG8 and ETO) and generate a RUNX1–RUNX1T1 fusion protein. Molecular characterization of the translocation break points in a t(5;8)(q32;q21.3) patient with mild-to-moderate mental retardation and congenital heart disease revealed that one of the break points was within the RUNX1T1 gene. Analysis of RUNX1T1 expression in human embryonic and fetal tissues suggests a role of RUNX1T1 in brain and heart development and support the notion that disruption of the RUNX1T1 gene is associated with the patient''s phenotype.     

Immunolocalization of TGF-beta2 in the rat thymus during late stages of prenatal development

The aim of this study was to investigate the immunolocalization of transforming growth factor beta (TGF-beta2) in rat thymic stromal cells and thymocytes and investigate the roles of TGF-beta2 in thymopoiesis during the late stages of fetal development. Twelve adult pregnant female Wistar rats weighing 250-270 g were used in this study. The rats were killed by cervical dislocation on gestation days 16 (GD16), 18 (GD18) and 20 (GD20). Fetal thymus glands were prepared and examined by an immunohistochemical technique to reveal binding of an anti-TGF-beta2 rabbit polyclonal antibody. The thymic primordium was surrounded with a connective tissue capsule at GD16 and at this stage TGF-beta2 immunoreactivity was not observed. At GD18, the connective tissue capsule had formed septa which subdivided the tissue into lobules and at this stage TGF-beta2 immunolocalization was detected in the capsule and in thymocytes. Lobulation was more evident at GD20 and TGF-beta2 immunoreactivity of thymocytes was more extensive than on GD18. Results indicate that TGF-beta2 may play an important role in the organization or development of thymocytes in the late stages of thymopoiesis.     

Trmt112 gene expression in mouse embryonic development

Mouse Trmt112, the homologous gene of yeast Trm112 (tRNA methyltransferase 11-2), was initially cloned from RIKEN with uncertain function. The yeast TRM112 is now known to play important roles in RNA methylation. Here, we studied the expression of Trmt112 by in situ hybridization and quantitative real-time RT-PCR (QRT-PCR). A higher expression level of Trmt112 was observed in the brain and nervous system by whole mount in situ hybridization from embryonic day 10.5 (E10.5) to E11.5. At later developmental stages E13.5 and E16.5, abundant expression was prominently found in various organs and tissues including developing brain, nervous system, thymus, lung, liver, intestine, kidney, and cartilage. Furthermore, Trmt112 was persistently expressed from E9.5 to E18.5 on whole embryos and highly expressed in multiple organs at E12.5, E15.5 and E18.5 by QRT-PCR. These results showed that Trmt112 gene was highly and ubiquitously expressed during mouse embryonic development, implying that it might be involved in the morphogenesis of diverse organs and tissues and numerous physiological functions.     

Observations on the thermoregulatory effects of preoptic warming in rats

Experimental warming of the preoptic-anterior hypothalamic area was used to evaluate behavioral and autonomic thermoregulatory heat-loss responses. Hypothalamic warming was associated with reduced behavioral heat intake and decreased core and peripheral temperatures in rats working for radiant heat reward in a cold environment. Baseline rates of responding for external heat were determined by ambient temperature, but the magnitude of changes in core or peripheral temperatures during preoptic warming were not. Behavioral responses compensated for variations in ambient temperature so that the threshold hypothalamic temperature above which heat loss was activated by preoptic warming was not altered by changing ambient temperatures. Heat loss during hypothalamic warming was a function of both autonomic and behavioral thermoregulatory responses because the decrease in body heat content during preoptic warming could not be accounted for by the decreased behavioral heat intake alone. The threshold hypothalamic temperature for elicitation of tail vasodilation decreased systematically as ambient temperature increased when no behavioral option was available. In the rat, both behavioral and autonomic thermoregulatory responses cooperate to determine the magnitude of heat loss which is proportional to the magnitude of preoptic warming.