A New Eocene Dasypodid with Caniniforms (Mammalia,Xenarthra, Cingulata) from Northwest Argentina

The aim of this work is to present a new genus and species of Dasypodidae from the Lumbrera Formation (“lower Lumbrera”), early-middle Eocene of Salta Province, northwest Argentina. The new taxon, documented by one specimen, consists of an incomplete skull and jaw with teeth housed in their alveoli, postcranial remains, and isolated osteoderms. Lumbreratherium oblitum, gen. et sp. nov., is characterized by heterodont dentition, with a caniniform as the first tooth, diastema between caniniform and first molariform, teeth with closed roots, and a peculiar morphology of the osteoderms. A phylogenetic analysis indicates that Lumbreratherium oblitum, gen. et sp. nov., and Pucatherium parvum belong to a monophyletic clade in a basal position within the Cingulata. The singularity of the morphological characteristics of these Paleogene armadillos of northwest Argentina reinforces the hypothesis of an intertropical origin of mammal clades different from those of the Paleogene in more austral regions of Argentina.     

Invaders Without Frontiers: Cross-border Invasions of Exotic Mammals

We address cross-border mammal invasions between Chilean and Argentine Patagonia, providing a detailed history of the introductions, subsequent spread (and spread rate when documented), and current limits of mammal invasions. The eight species involved are the following: European hare (Lepus europaeus), European rabbit (Oryctolagus cuniculus), wild boar (Sus scrofa), and red deer (Cervus elaphus) were all introduced from Europe (Austria, France, Germany, and Spain) to either or both Chilean and Argentine Patagonia. American beaver (Castor canadensis) and muskrat (Ondatra zibethicus) were introduced from Canada to Argentine Tierra del Fuego Island (shared with Chile). The American mink (Mustela vison) apparently was brought from the United States of America to both Chilean and Argentine Patagonia, independently. The native grey fox (Pseudalopex griseus) was introduced from Chilean to Argentine Tierra del Fuego. Few spread rates are available: the lowest are 10 km/yr and correspond to American beaver and American mink; intermediate rates are observed in muskrat and rather questionably, in grey fox; the highest rates (10–20 km/yr) are found among European hare and European rabbit. Because of their frequent migration, it is difficult to estimate the natural spread rate for wild boar and red deer. Not all mammal invasions in Chilean and Argentine Patagonia have been methodical advances of species; some involve an overlap of invasion fronts, with advances and retreats, and perhaps with re-invasions to different areas of either country. Because national policies with regard to introduced species may differ between countries sharing porous borders, it seems advisable to coordinate such policies in order to prevent the entry of unwelcome invaders.     

Fiber architecture of canine abdominal muscles.

During respiration, abdominal muscles experience loads, not only in the muscle-fiber direction but also transverse to the fibers. We wondered whether the abdominal muscles exhibit a fiber architecture that is similar to the diaphragm muscle, and, therefore, we chose two adjacent muscles: the internal oblique (IO), with about the same muscle length as the diaphragm, and the transverse abdominis (TA), which is twice as long as the diaphragm. First, we used acetylcholinesterase staining to examine the distribution of neuromuscular junctions on both surfaces of the TA and IO muscles in six dogs. A maximum of four irregular bands of neuromuscular junctions crossed the IO, and as many as six bands crossed the TA, which is consistent with a discontinuous fiber architecture. In six additional dogs, we examined fiber architecture of these muscles by microdissecting 103 fascicles from the IO and 139 from the TA. Each fascicle contained between 20 and 30 muscle fibers. The mean length of nonspanning fibers (NSF) ranged from 2.8 +/- 0.3 cm in the IO to 4.3 +/- 0.5 cm in the TA, and the mean length of spanning fibers ranged from 4.3 +/- 0.5 cm in the IO to 7.6 +/- 1.4 cm in the TA. NSF accounted for 89.6 +/- 1.5% of all fibers dissected from the IO and 99.1 +/- 0.2% of all fibers dissected from the TA. The percentage of NSF with both ends tapered was 6.2 +/- 1.0 and 41.0 +/- 2.3% for IO and TA, respectively. These data show that fiber architecture in either IO or TA is discontinuous, with much more short-tapered fibers in the TA than in the IO. When abdominal muscles are submaximally activated, as during both normal expiration and maximal expiratory efforts, muscle force could be transmitted to the cell membrane and to the extracellular intramuscular connective tissue by shear linkage, presumably via structural transmembrane proteins.     

CD38 is associated with lipid rafts and upon receptor stimulation leads to Akt/protein kinase B and Erk activation in the absence of the CD3-zeta immune receptor tyrosine-based activation motifs.

T lymphocytes can be activated via the T cell receptor (TCR) or by triggering through a number of other cell surface structures, including the CD38 co-receptor molecule. Here, we show that in TCR+ T cells that express a CD3-zeta lacking the cytoplasmic domain, cross-linking with CD38- or CD3-specific monoclonal antibodies induces tyrosine phosphorylation of CD3-epsilon, zeta-associated protein-70, linker for activation of T cells, and Shc. Moreover, in these cells, anti-CD38 or anti-CD3 stimulation leads to protein kinase B/Akt and Erk activation, suggesting that the CD3-zeta-immunoreceptor tyrosine-based activation motifs are not required for CD38 signaling in T cells. Interestingly, in unstimulated T cells, lipid rafts are highly enriched in CD38, including the T cells lacking the cytoplasmic tail of CD3-zeta. Moreover, CD38 clustering by extensive cross-linking with an anti-CD38 monoclonal antibody and a secondary antibody leads to an increased resistance of CD38 to detergent solubilization, suggesting that CD38 is constitutively associated with membrane rafts. Consistent with this, cholesterol depletion with methyl-beta-cyclodextrin substantially reduces CD38-mediated Akt activation while enhancing CD38-mediated Erk activation. CD38/raft association may improve the signaling capabilities of CD38 via formation of protein/lipid domains to which signaling-competent molecules, such as immunoreceptor tyrosine-based activation motif-bearing CD3 molecules and protein-tyrosine kinases, are recruited.     

The Effect of Riffle-Scale Environmental Variability on Macroinvertebrate Assemblages in a Tropical Stream

In a tropical stream (at the Soberaní;a National Park, Panama), different environmental factors were quantified in riffle habitats (water characteristics: velocity, depth, turbulence, and direction; stone characteristics: surface area, sphericity, and degree of burial; and others: substrate type, and canopy cover). Characteristics of macroinvertebrate assemblages (mean density of individuals, mean taxon richness, and cumulative taxon richness in three stones at each riffle) were related to both mean values and variability of these environmental factors at riffle scale. Macroinvertebrate density was higher in shallow, fast flowing, stony riffles, with low variability in dominant substrate type. Taxon richness was also higher in shallow riffles with loose, not buried stones, and water direction more or less parallel to the bank. Environmental variability resulted as important as mean values of environmental factors to explain variation in macroinvertebrate assemblages. This is the first study, to our knowledge, that quantifies substratum variability and demonstrates its influence on macroinvertebrate assemblages in a tropical stream.     

Ability of the Actiwatch Accelerometer to Predict Free‐Living Energy Expenditure in Young Children

Objective: To determine whether activity counts obtained with the Actiwatch monitor are associated with total expenditure and body composition in young children. Research Methods and Procedures: Actiwatch activity monitors were tested in 29 children 4 to 6 years old under field conditions over eight days. Total energy expenditure (TEE) was assessed with the doubly labeled water (DLW) technique. Correlation analyses were used to identify variables related to energy expenditure and percentage body fat. Multiple linear regression analyses were used to examine the variance in TEE and percentage body fat explained by activity counts after adjusting for relevant covariates. Results: Both average total daily activity counts (658, 816 ± 201, 657) and the pattern of activity were highly variable among subjects. TEE was significantly related to lean body mass (r = 0.45) and age (r = 0.48; p < 0.05 for both). Activity counts alone were not associated with TEE. In multiple linear regression analyses, TEE was independently associated with only lean body mass. Percentage fat mass was independently associated with body weight, being a girl, and being white, but not with average total activity counts. Discussion: Activity counts obtained with the Actiwatch under free‐living conditions do not reflect TEE in 4‐ to 6‐year‐old children and are not correlated with percentage fat mass. Therefore, average total activity counts obtained with the Actiwatch may be of limited value in identifying children at risk for becoming obese.     

Leptin and Altitude in the Cardiovascular Diseases

Objective: The lower mortality from coronary ischemic disease in populations living at high altitude has been related to an increase of high‐density lipoprotein (HDL)‐cholesterol at altitude. Leptin has been proposed as a cardiovascular risk factor. We investigated whether leptin varies according to the altitude at which people live. Research Methods and Procedures: This was a cross‐sectional study of the first 889 people enrolled in a cohort study in the Canary Islands, Spain. The relationship among serum leptin, altitude, obesity, and other cardiovascular risk factors was analyzed by bivariate and multivariate tests. Results: Leptin levels showed an inverse correlation to altitude expressed in meters (r = ?0.10). Obese subjects had this leptin‐altitude association (r = ?0.19), but they also had a direct correlation of leptin to HDL‐cholesterol (r = 0.27) and an inverse correlation of leptin to the total cholesterol‐to‐HDL‐cholesterol ratio (r = ?0.34), triglycerides (r = ?0.29), apolipoprotein B (r = ?0.21), and glycemia (r = ?0.19). Nonobese subjects had only the leptin‐altitude association (r = ?0.11). The final regression model included altitude as predictor. Other associated variables were gender, physical activity, BMI, age, smoking (reducing leptin independently of BMI), alcohol, heart rate, and income. Discussion: Serum leptin level decreases when altitude increases, and this association could help to explain the lower cardiovascular mortality rate at high altitude. However, because in obese subjects there is a direct association of leptin with HDL‐cholesterol and an inverse association with the lipid atherogenic fractions, we suggest the hypothesis of different roles for bound and free leptin, with free leptin being a cardiovascular protective factor in obese people.     

Effect of weather variables on the population fluctuation of muroid Calomys venustus in central Argentina

The effects of weather on population fluctuation patterns of the South American muroid Calomys venustus were studied. Box–Jenkins data series analysis and anova were used to describe the relationship between climatic variables and population. No relation was found between maximum temperatures or precipitation and the C. venustus population. Temperatures below 4 °C appear to affect populations of the overwintered cohort after a time lag of 5 months.     

Eichhornia crassipes-based tertiary treatment of Kraft pulp mill effluents in Chilean Central Region

This paper presents experimental results on the implementation of Eichhornia crassipes–based tertiary lagoon to treat effluents generated by a 300 ton d^–1 Kraft pulp mill in Chile. Results show that E. crassipes rapidly adapted to the tertiary lagoon conditions. Active growth was maintained even during a cold winter, protected by the wastewater heat content. A 1000 m² seeding area extended to 2300–6200 m² after a month of growth, with a monthly harvested biomass and nitrogen uptake were 1.1–5.4 ton (dry wt.), and 18–127 kg N, respectively. E. crassipes growth was adequately described by a first order model, with an estimated rate constant ca. 0.03 d^–1 and 0.06 d^–1, for winter and summer seasons, respectively. A management strategy based on such model, to account for seasonal variations in growth rate while keeping a constant nitrogen uptake capacity, is proposed here.