Synthesis of chicken galanin and its N- and C-terminal segments,and preparation of their antisera

Summary We describe the synthesis of the first avian galanin (GAL), chicken GAL, and its N-terminal and C-terminal segments by solid-phase synthesis, using Boc/Bzl amino acid protection groups and MBHA resin. The three peptides were prepared with purities of over 97%, as determined by RP-HPLC, HPCE, FAB-MS or ESI-MS and amino acid analysis. Antibodies against these synthetic peptides were raised in rabbits and used for immunohistochemical localization of GAL-immunoreactive neurons in chicken brain.     

Ontogenetic development of corticotropin-releasing factor (CRF)-containing neural elements in the brain of the chicken during incubation and after hatching

Summary In chicken embryos of different ages and in young chickens after hatching, neural elements reacting with antibodies generated against synthetic ovine corticotropin-releasing factor (CRF) were studied by means of the peroxidase-anti-peroxidase (PAP) technique at the lightmicroscopic level. CRF-immunoreactivity was first observed in perikarya located in the periventricular part of the hypothalamus on the 14th day of the incubation period. CRF-containing neural elements were detected on the same day of incubation in the external zone of the median eminence, but not in all investigated animals. In extrahypothalamic sites, immunoreactive perikarya were demonstrable in the central gray of the mesencephalon on the 15th day of incubation. Furthermore, immunoreactive cells appeared in other brain regions such as nucleus accumbens and dorsomedial nucleus of the thalamus after hatching. The present observations provide information regarding the functional development of the hypothalamo-hypophyseal-adrenal axis in the chick embryo.     

Estimation of the mean distance of closest approach of some heavy metal ions in aqueous solutions: some experimental and theoretical calculations

The estimation of numerical values of the mean distance of closest approach of ions, a, of heavy metal ion salts in aqueous solutions, determined from activity coefficients, as well as from different theoretical approaches, is presented and discussed.     

Quantitative determination by real-time PCR of four vaginalLactobacillus species,Gardnerella vaginalisandAtopobium vaginaeindicates an inverse relationship betweenL. gasseriandL. iners

Background  

Most studies of the vaginal microflora have been based on culture or on qualitative molecular techniques. Here we applied existing real-time PCR formats forLactobacillus crispatus,L. gasseriandGardnerella vaginalisand developed new formats forAtopobium vaginae,L. inersandL. jenseniito obtain a quantitative non culture-based determination of these species in 71 vaginal samples from 32 pregnant and 28 non-pregnant women aged between 18 and 45 years.     

APETALA2 regulates the stem cell niche in the Arabidopsis shoot meristem

Postembryonic organ formation in higher plants relies on the activity of stem cell niches in shoot and root meristems where differentiation of the resident cells is repressed by signals from surrounding cells. We searched for mutations affecting stem cell maintenance and isolated the semidominant l28 mutant, which displays premature termination of the shoot meristem and differentiation of the stem cells. Allele competition experiments suggest that l28 is a dominant-negative allele of the APETALA2 (AP2) gene, which previously has been implicated in floral patterning and seed development. Expression of both WUSCHEL (WUS) and CLAVATA3 (CLV3) genes, which regulate stem cell maintenance in the wild type, were disrupted in l28 shoot apices from early stages on. Unlike in floral patterning, AP2 mRNA is active in the center of the shoot meristem and acts via a mechanism independent of AGAMOUS, which is a repressor of WUS and stem cell maintenance in the floral meristem. Genetic analysis shows that termination of the primary shoot meristem in l28 mutants requires an active CLV signaling pathway, indicating that AP2 functions in stem cell maintenance by modifying the WUS-CLV3 feedback loop.     

Seed to seedling transitions in successional habitats across a tropical landscape

Recognition that tree recruitment depends on the balance between seed arrival and seedling survival has led to a surge of interest in seed‐dispersal limitation and seedling‐establishment limitation in primary forests. Virtually unaddressed are comparisons of this balance in mature and early successional habitats. We assessed seed rain and seedling recruitment dynamics of tree species in primary forest, secondary forest and pasture released from grazing in a tropical agricultural landscape. Seed to seedling ratios (seed effectiveness; Φ_i) for 43 species in southern Mexico determined differences in the extent to which seeds produced seedlings by habitat, life history, and dispersal mode. Reproductive potential as estimated by the transition from seed rain to seedling recruitment, differed by habitats, and varied dramatically by life history and dispersal mode. Expected recruit densities (E_it) were higher for animal‐dispersed than wind‐dispersed species, and for non‐pioneer than pioneer species. Non‐pioneers and animal‐dispersed species had higher expected relative recruit abundance (ε_it) in primary forest (median of 4 seeds recruit^?1) whereas in secondary forest wind‐dispersed pioneers had the highest expected relative recruit abundance (median of 16 seeds per recruit). In pastures, wind‐dispersed pioneer species were most successful with many more seeds per recruit (median of 291) than both forest habitats. Seeds per recruit (Φ_i) appeared to decrease with increase in seed mass for 43 species for which data were available (r = –0.55, P < 0.001). This was associated with a negative correlation of Φ_i with seed size in primary forest (r = –0.50, P = 0.08 for 13 species); Φ_i was not correlated with seed size in secondary forest (n = 16) or pasture (n = 14). Metrics of seeds per recruit, expected recruit density and expected relative recruit abundance dramatically illustrate differences in barriers to recruitment in successional habitats.