Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Characterization and the broad cross‐species applicability of 20 anonymous nuclear loci isolated from the Taiwan Hwamei (Garrulax taewanus)

We isolated 20 anonymous nuclear loci (8556 bp in total) from the Taiwan Hwamei (Garrulax taewanus), an endemic songbird of Taiwan. A panel of nine to 15 individuals with unknown relationship was used to characterize polymorphism of these loci. We identified 46 single nucleotide polymorphic sites (SNPs) in 15 polymorphic loci. Frequency of SNPs was one per every 186 bp in average. Nucleotide diversity, θ, ranged from 0.00054 to 0.00371 per locus. We also tested cross‐species applicability of these loci on 17 species from eight different passerine families. All 20 loci could be successfully amplified (ranged from one to 16 species, mean = 7.9 species).     

Pooled analysis of loss of heterozygosity in breast cancer: a genome scan provides comparative evidence for multiple tumor suppressors and identifies novel candidate regions

Somatic loss of heterozygosity (LOH) has been widely reported in breast cancer as a means of identifying putative tumor-suppressor genes. However, individual studies have rarely spanned more than a single chromosome, and the varying criteria used to declare LOH complicate efforts to formally differentiate regions of consistent versus sporadic (random) loss. We report here the compilation of an extensive database from 151 published LOH studies of breast cancer, with summary data from >15,000 tumors and primary allelotypes from >4,300 tumors. Allelic loss was evaluated at 1,168 marker loci, with large variation in the density of informative observations across the genome. Using studies in which primary allelotype information was available, we employed a likelihood-based approach with a formal chromosomal instability and selection model. The approach seeks direct evidence for preferential loss at each locus compared with nearby loci, accounts for heterogeneity across studies, and enables the direct comparison of candidate regions across the genome. Striking preferential loss was observed (in descending order of significance) in specific regions of chromosomes 7q, 16q, 13q, 17p, 8p, 21q, 3p, 18q, 2q, and 19p, as well as other regions, in many cases coinciding with previously identified candidate genes or known fragile sites. Many of these observations were not possible from any single LOH study, and our results suggest that many previously reported LOH results are not systematic or reproducible. Our approach provides a comparative framework for further investigation of regions exhibiting LOH and identifies broad genomic regions for which there exist few data.     

Theoretical and experimental comparisons of gene expression indexes for oligonucleotide arrays

MOTIVATION: Oligonucleotide expression arrays exhibit systematic and reproducible variation produced by the multiple distinct probes used to represent a gene. Recently, a gene expression index has been proposed that explicitly models probe effects, and provides improved fits of hybridization intensity for arrays containing perfect match (PM) and mismatch (MM) probe pairs. RESULTS: Here we use a combination of analytical arguments and empirical data to show directly that the estimates provided by model-based expression indexes are superior to those provided by commercial software. The improvement is greatest for genes in which probe effects vary substantially, and modeling the PM and MM intensities separately is superior to using the PM-MM differences. To empirically compare expression indexes, we designed a mixing experiment involving three groups of human fibroblast cells (serum starved, serum stimulated, and a 50:50 mixture of starved/stimulated), with six replicate HuGeneFL arrays in each group. Careful spiking of control genes provides evidence that 88-98% of the genes on the array are detectably transcribed, and that the model-based estimates can accurately detect the presence versus absence of a gene. The use of extensive replication from single RNA sources enables exploration of the technical variability of the array.     

The gamma-tubulin gene family in humans

Despite the central role of gamma-tubulin in the organization of the microtubule cytoskeleton, the gamma-tubulin gene family in humans has not been characterized. We now report the identification of a second expressed human gamma-tubulin gene (TUBG2) and a gamma-tubulin pseudogene (TUBG1P) in addition to the previously identified gamma-tubulin gene (TUBG1). Evidence from Southern hybridizations suggests that there are probably no additional gamma-tubulin sequences in the human genome. TUBG1 and TUBG2 are within 20 kb of each other in region q21 of chromosome 17, and TUBG1P is on chromosome 7. The proteins encoded by TUBG1 and TUBG2 share 97.3% amino acid identity, and the two genes are coexpressed in a variety of tissues. Previous studies of gamma-tubulin in human tissues and cell lines have been based on the tacit assumption that a single gamma-tubulin (the gamma-tubulin encoded by TUBG1) was present. While this assumption is not correct, the similarity of the products of TUBG1 and TUBG2 suggests that results of previous immunolocalization and immunoprecipitation studies in human cells and tissues are likely to be valid. In addition, any pharmacological agents that target one human gamma-tubulin are likely to target both.     

Protein synthesis-independent plasticity mediates rapid and precise recovery of deprived eye responses

Monocular deprivation (MD) for a few days during a critical period of development leads to loss of cortical responses to stimulation of the deprived eye. Despite the profound effects of MD on cortical function, optical imaging of intrinsic signals and single-unit recordings revealed that deprived eye responses and orientation selectivity recovered a few hours after restoration of normal binocular vision. Moreover, recovery of deprived eye responses was not dependent upon mRNA translation, but required cortical activity. Interestingly, this fast recovery and protein synthesis independence was restricted to the hemisphere contralateral to the previously deprived eye. Collectively, these results implicate a relatively simple mechanistic process in the reactivation of a latent set of connections following restoration of binocular vision and provide new insight into how recovery of cortical function can rapidly occur in response to changes in sensory experience.     

Seasonality of Rotifers and Temperature in Lough Neagh,N. Ireland

Long runs of seasonal rotifer population data allow analysis of seasonal occurrence using mathematical tools. The application of Fourier analysis to a 15 year dataset describes seasonality in simple mathematical terms. This facilitates comparison of population expression with potential population driving variables and provides a basic modelling tool. Results show that annual patterns of occurrence and density have linkages with annual maximum and minimum environmental temperature, although the exact relationships are not clear.     

Electrocommunication behaviour and non invasively-measured androgen changes following induced seasonal breeding in the weakly electric fish, Apteronotus leptorhynchus

Androgens are known to be involved in reproductive behaviours including courtship and aggression. According to the Challenge Hypothesis, androgen activity upregulates male reproductive behaviour seasonally and also modulates short term adaptation of these behaviours in response to social context. In the weakly electric fish, Apteronotus leptorhynchus, 11-ketotestosterone (11-KT) has been previously implicated in the regulation of electrocommunication behaviours that are believed to have roles in both aggression and courtship. Changes in male 11-KT levels were quantified using a non-invasive measurement technique alongside changes in electrocommunication behaviour following environmental cues that simulated the onset of the breeding season. Males showed an increase in mean electric organ discharge frequency (EODf), which is consistent with earlier results showing a female preference for high EODf. A subset of males with high initial EODfs showed increases in both 11-KT and EODf, which provides support for an EODf-based dominance hierarchy in this species. Males housed in social conditions and exposed to breeding conditioning also showed higher overall electric organ discharge frequencies and 11-KT compared to males housed in isolation. Evidence is presented that another type of electrocommunication signal previously implicated in courtship may also serve as an inter-male signal of submission. Our results are consistent with earlier observations that electrocommunication signals produced during inter-male aggression serve in deterring attacks, and their pattern of production further suggested the formation of a dominance hierarchy.