Environmental and historical constraints on global patterns of amphibian richness

Our knowledge of the broad-scale ecology of vertebrate ectotherms remains very limited. Despite ongoing declines and sensitivity to environmental change, amphibian distributions are particularly poorly understood. We present a global analysis of contemporary environmental and historical constraints on amphibian richness, the first for an ectotherm clade at this scale. Amphibians are presumed to experience environmental constraints distinct from those of better studied endothermic taxa due to their stringent water requirements and the temperature dependence of their energetic costs and performance. Single environmental predictors set upper bounds on, but do not exclusively determine, amphibian richness. Accounting for differing regional histories of speciation and extinction helps resolve triangular or scattered relationships between core environmental predictors and amphibian richness, as the relationships' intercepts or slopes can vary regionally. While the magnitude of richness is strongly determined by regional history, within-region patterns are consistently jointly driven by water and temperature. This confirms that ecophysiological constraints extend to the broad scale. This coupling suggests that shifts in climatic regimes will probably have dramatic consequences for amphibians. Our results illustrate how the environmental and historical explanations of species richness gradients can be reconciled and how the perspectives are complements for understanding broad-scale patterns of diversity.     

Prospective identification of myogenic endothelial cells in human skeletal muscle

We document anatomic, molecular and developmental relationships between endothelial and myogenic cells within human skeletal muscle. Cells coexpressing myogenic and endothelial cell markers (CD56, CD34, CD144) were identified by immunohistochemistry and flow cytometry. These myoendothelial cells regenerate myofibers in the injured skeletal muscle of severe combined immunodeficiency mice more effectively than CD56+ myogenic progenitors. They proliferate long term, retain a normal karyotype, are not tumorigenic and survive better under oxidative stress than CD56+ myogenic cells. Clonally derived myoendothelial cells differentiate into myogenic, osteogenic and chondrogenic cells in culture. Myoendothelial cells are amenable to biotechnological handling, including purification by flow cytometry and long-term expansion in vitro, and may have potential for the treatment of human muscle disease.     

Optimization of TCR transgenic T cells for in vivo tracking of immune responses

T-cell receptor (TCR) transgenic mice have proven useful for the study of various immune parameters. Despite this, it has been suggested that transferred T cells respond differently to their endogenous counterparts at least in terms of conversion to antigen-experienced populations bearing memory cell markers. Here, we have compared the response of TCR transgenic T cells to endogenous populations within the context of infection with herpes simplex virus. We found that adoptive transfer at numbers approaching those of the endogenous virus-specific subset results in a response with similar kinetics, magnitude and memory subset conversion. This suggests that this form of optimized T-cell transfer remains a useful means of tracking antiviral immune responses.     

Formation of filopodia in earthworm (Lumbricus terrestris) coelomocytes in response to osmotic stress

Coelomocytes, the immunodefense cells of the earthworm Lumbricus terrestris, are exposed to changing osmotic pressures as the worm's coelomic fluid responds to fluctuating wet-dry conditions of the surrounding soil. Using light and fluorescence microscopy combined with actin and tubulin disrupting drugs, we determined the effects of changing osmotic pressure on coelomocyte morphology. The coelomocytes from L. terrestris respond to an increase in environmental osmotic pressure from isotonic conditions (170 mOsm) to hypertonic conditions (715 mOsm) by changing from a round/petalloid morphology to a filopodial morphology. Cytoskeletal fluorescent staining studies indicate that for filopodia to form, the actin cortical ring, present in most coelomocytes in isotonic conditions, must be disrupted. Breakdown of the actin ring by exposure to a hypertonic environment or actin disrupting drugs allows the formation of actin or tubulin-based filopodia. The filopodia, or podial-like extensions formed by earthworm coelomocytes, may enable the cells to better explore their environment.     

In vitro and in vivo evaluation of Alexa Fluor 680-bombesin[7-14]NH2 peptide conjugate, a high-affinity fluorescent probe with high selectivity for the gastrin-releasing peptide receptor

Gastrin-releasing peptide (GRP) receptors are overexpressed on several types of human cancer cells, including breast, prostate, small cell lung, and pancreatic cancers. Bombesin (BBN), a 14-amino acid peptide that is an analogue of human GRP, binds to GRP receptors with very high affinity and specificity. The aim of this study was to develop a new fluorescent probe based on BBN having high tumor uptake and optimal pharmacokinetics for specific targeting and optical imaging of human breast cancer tissue. In this study, solid-phase peptide synthesis was used to produce H(2)N-glycylglycylglycine-BBN[7-14]NH(2) peptide with the following general sequence: H(2)N-G-G-G-Q-W-A-V-G-H-L-M-(NH(2)). This conjugate was purified by reversed-phase high-performance liquid chromatography and characterized by electrospray-ionization mass spectra. The fluorescent probe Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) conjugate was prepared by reaction of Alexa Fluor 680 succinimidyl ester to H(2)N-G-G-G-BBN[7-14]NH(2) in dimethylformamide (DMF). In vitro competitive binding assays, using (125)I-Tyr(4)-BBN as the radiolabeling gold standard, demonstrated an inhibitory concentration 50% value of 7.7 +/- 1.4 nM in human T-47D breast cancer cells. Confocal fluorescence microscopy images of Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) in human T-47D breast cancer cells indicated specific uptake, internalization, and receptor blocking of the fluorescent bioprobe in vitro. In vivo investigations in SCID mice bearing xenografted T-47D breast cancer lesions demonstrated the ability of this new conjugate to specifically target tumor tissue with high selectivity and affinity.     

Differences in nutritional status between rural and urban Yucatec Maya children: The importance of early life conditions

Early-life conditions shape childhood growth and are affected by urbanization and the nutritional transition. To investigate how early-life conditions (across the “first” and “second” 1000 days) are associated with rural and urban children's nutritional status, we analyzed anthropometric data from Maya children in Yucatan, Mexico. We collected weight, height and triceps skinfold measures, then computed body mass and fat mass indices (BMI/FMI), in a cross-sectional sample of 6-year-olds (urban n = 72, rural n = 66). Demographic, socioeconomic and early-life variables (birthweight/mode, rural/urban residence, household crowding) were collected by maternal interview. We statistically analyzed rural-urban differences in demographic, socioeconomic, early-life, and anthropometric variables, then created linear mixed models to evaluate associations between early-life variables and child anthropometric outcomes. Two-way interactions were tested between early-life variables and child sex, and between early-life variables and rural-urban residence. Results showed that rural children were shorter-statured, with lower overweight/obesity and cesarean delivery rates, compared to urban children. Household crowding was a negative predictor of anthropometric outcomes; the strongest effect was in boys and in urban children. Birthweight positively predicted anthropometric outcomes, especially weight/BMI. Birth mode was positively (not statistically) associated with any anthropometric outcome. Cesarean delivery was more common in boys than in girls, and predicted increased height in urban boys. In conclusion, urbanization and household crowding were the most powerful predictors of Maya 6-year-old anthropometry. The negative effects of crowding may disproportionately affect Maya boys versus girls and urban versus rural children. Early-life conditions shape Maya children's nutritional status both in the “first” and “second” 1000 days.     

Twenty year contrast of non-native parrotfeather distribution and abundance in an unregulated river

Hydrobiologia - Efficient management of invasive species benefits from understanding patterns of persistence and change over time. In this study, we compare distribution and abundance of the...