Accumulation of pyrroline 5-carboxylic acid in conditioned medium of cultured fibroblast: Stimulatory effects of serum,insulin, and IGF-1

Summary Pyrroline 5-carboxylate, an intermediate of amino acid metabolism, is released into medium by cultured normal human fibroblasts. With cells made quiescent by serum starvation, the addition of 10% fetal bovine serum augmented the release of pyrroline 5-carboxylate into medium by 2.5-fold. Although platelet-derived growth factor was without effect, both insulin and insulinlike growth factor-1 nearly reproduced the serum effect. The dose-dependence of insulin and insulinlike growth factor 1 effects suggested their mediation by their own respective receptors. Although the mechanism for the stimulatory effect remains unknown, these effects of insulin and insulinlike growth factor 1 on pyrroline 5-carboxylate suggest hormonal regulation of pyrroline 5-carboxylate release.     

Touch receptor development and function in Caenorhabditis elegans

Mutations causing a touch-insensitive phenotype in the nematode Caenorhabditis elegans have been the basis of studies on the specification of neuronal cell fate, inherited neurodegeneration, and the molecular nature of mechanosensory transduction. © 1993 John Wiley & Sons, Inc.     

In vitro development of bovine secondary follicles in two- and three-dimensional culture systems using vascular endothelial growth factor,insulin-like growth factor-1, and growth hormone

The aim of this study was to evaluate the development and estradiol production of isolated bovine secondary follicles in two-dimensional (2D, experiment 1) and three-dimensional (3D using alginate, experiment 2) long-term culture systems in the absence (control group; only α-MEM⁺) or presence of vascular endothelial growth factor (VEGF), insulin-like growth factor-1, or GH alone, or a combination of all. A total of 363 isolated secondary follicles were cultured individually for 32 days at 38.5 °C in 5% CO₂ in a humidified incubator with addition of medium (5 μL) every other day. In 2D culture system, follicular growth and antrum formation rates were higher (P < 0.05) in VEGF treatment compared with the other treatments. In 3D culture system, only estradiol concentration was greater (P < 0.05) in the GH than in the control group, whereas the other end points were similar (P > 0.05). In summary, this study demonstrated that the benefits of using a certain type of medium supplement depended on the culture system (2D vs. 3D). Vascular endothelial growth factor was an effective supplement for the in vitro culture of bovine secondary follicles when the 2D culture system was used, whereas GH only affected estradiol production using the 3D culture system. This study sheds light on advancements in methodology to facilitate subsequent studies on bovine preantral follicle development.     

Modeling the formation of root apices

The formation of new root apices from small groups of cells with different cellular patterns has been simulated using an existing model based on growth tensors. To generate an apex, a steady growth field was used. The pattern of cells evolved to approach the steady state. Two extreme types of progressions have been obtained : one leading to an apex with a single or a few apical cells, and the other to an apex with a quiescent centre. The change of structure while applying a steady growth tensor indicates that development may involve a succession of discrete growth tensors.     

Identification of cardiac stem cells within mature cardiac myocytes

Cardiac stem cells are described in a number of mammalian species including humans. Cardiac stem cell clusters consisting of both lineage-negative and partially committed cells are generally identified between contracting cardiac myocytes. In the present study, c-kit⁺, Sca⁺, and Isl1⁺ stem cells were revealed to be located inside the sarcoplasm of cardiac myocytes in myocardial cell cultures derived from newborn, 20-, and 40-day-old rats. Intracellularly localized cardiac stem cells had a coating or capsule with a few pores that opened into the host cell sarcoplasm. The similar structures were also identified in the suspension of freshly isolated myocardial cells (ex vivo) of 20- and 40-day-old rats. The results from this study provide direct evidence for the replicative division of encapsulated stem cells, followed by their partial cardiomyogenic differentiation. The latter is substantiated by the release of multiple transient amplifying cells following the capsule rupture. In conclusion, functional cardiac stem cells can reside not only exterior to but also within cardiomyocytes.     

Genome‐wide scans to detect positive selection in Large White and Tongcheng pigs

Due to the direction, intensity, duration and consistency of genetic selection, especially recent artificial selection, the production performance of domestic pigs has been greatly changed. Therefore, we reasoned that there must be footprints or selection signatures that had been left during domestication. In this study, with porcine 60K BeadChip genotyping data from both commercial Large White and local Chinese Tongcheng pigs, we calculated the extended haplotype homozygosity values of the two breeds using the long‐range haplotype method to detect selection signatures. We found 34 candidate regions, including 61 known genes, from Large White pigs and 25 regions comprising 57 known genes from Tongcheng pigs. Many selection signatures were found on SSC1, SSC4, SSC7 and SSC14 regions in both populations. According to quantitative trait loci and network pathway analyses, most of the regions and genes were linked to growth, reproduction and immune responses. In addition, the average genetic differentiation coefficient F_ST was 0.254, which means that there had already been a significant differentiation between the breeds. The findings from this study can contribute to further research on molecular mechanisms of pig evolution and domestication and also provide valuable references for improvement of their breeding and cultivation.     

Waterlogging and fire impacts on nitrogen availability and utilization in a subtropical wet heathland (wallum)

Protein, amino acids and ammonium were the main forms of soluble soil nitrogen in the soil solution of a subtropical heathland (wallum). After fire, soil ammonium and nitrate increased 90- and 60-fold, respectively. Despite this increase in nitrate availability after fire, wallum species exhibited uniformly low nitrate reductase activities and low leaf and xylem nitrate. During waterlogging soil amino acids increased, particularly γ-aminobutyric acid (GABA) which accounted for over 50% of amino nitrogen. Non-mycorrhizal wallum species were significantly (P < 0.05) ¹⁵N-enriched (0.3–4.3‰) compared to species with mycorrhizal associations (ericoid-type, ecto-, va-mycorrhizal) which were strongly depleted in ¹⁵N (-6.3 to -1.8‰). Lignotubers and roots had δ¹⁵N signatures similar to that of the leaves of respective species. The exceptions were fine roots of ecto-, ecto/va-, and ericoid type mycorrhizal species which were enriched in ¹⁵N (0.1–2.4‰). The 5¹⁵N signatures of δ¹⁵N_{total soil N} and δ¹⁵N_{soil NH4+} were in the range 3.7–4.5‰, whereas δ¹⁵N_{soil NO3?} was significantly (P < 0.05) more enriched in ¹⁵N (9.2–9.8‰). It is proposed that there is discrimination against ¹⁵N during transfer of nitrogen from fungal to plant partner. Roots of selected species incorporated nitrogen sources in the order of preference: ammonium > glycine > nitrate. The exception were proteoid roots of Hakea (Proteaceae) which incorporated equal amounts of glycine and ammonium.     

Correlation of ghrelin concentration and ghrelin,ghrelin-O-acetyltransferase (GOAT) and growth hormone secretagogue receptor 1a mRNAs expression in the proventriculus and brain of the growing chicken

To determine mechanisms for age-related decrease of GHS-R1a expression in the chicken proventriculus, changes in mRNA expression of ghrelin and ghrelin-O-acetyltransferase (GOAT) as well as ghrelin concentrations in the proventriculus and plasma were examined in growing chickens. Changes in expression levels of ghrelin, GOAT and GHS-R1a mRNAs were also examined in different brain regions (pituitary, hypothalamus, thalamus, cerebellum, cerebral cortex, olfactory bulb, midbrain and medulla oblongata). Ghrelin concentrations in the proventriculus and plasma increased with aging and reached plateaus at 30–50 days after hatching. High level of ghrelin mRNA decreased at 3 days after hatching, and it became stable at half of the initial level. Expression levels of GHS-R1a and GOAT decreased 3 or 5 days after hatching and became stable at low levels. Significant negative correlations were found between plasma ghrelin and mRNA levels of GOAT and GHS-R1a. Expression levels of ghrelin mRNA were different in the brain regions, but a significant change was not seen with aging. GHS-R1a expression was detected in all brain regions, and age-dependent changes were observed in the pituitary and cerebellum. Different from the proventriculus, the expression of GOAT in the brain increased or did not change with aging. These results suggest that decreased GHS-R1a and GOAT mRNA expression in the proventriculus is due to endogenous ghrelin-induced down-regulation. Expression levels of ghrelin, GOAT and GHS-R1a in the brain were independently regulated from that in the proventriculus, and age-related and region-dependent regulation pattern suggests a local effect of ghrelin system in chicken brain.