Enzymic activities and gene expression of enzymes of the acyl-CoA elongase during rapeseed development

Enzymic activities and gene expression of oleoyl-CoA elongase were studied during seed development using two different rapeseed cultivars, high-erucic-acid rapeseed (HEAR) and low-erucic-acid rapeseed (LEAR). The overall elongase activities were maximal in HEAR between the fourth and eighth weeks after pollination (WAP) and absent in LEAR. The 3-ketoacyl-CoA synthase (condensing enzyme, CE) mRNA levels and the developmental profiles in the two cultivars were different since maximal expression levels were detected in HEAR and LEAR at WAP 4 and WAP 6, respectively. Anti-CE antibodies revealed two proteins of 60 and 67 kDa in both cultivars and an additional reacting protein of 57 kDa in HEAR.     

Phytohormones in fruit development and maturation

Phytohormones are integral to the regulation of fruit development and maturation. This review expands upon current understanding of the relationship between hormone signaling and fruit development, emphasizing fleshy fruit and highlighting recent work in the model crop tomato (Solanum lycopersicum) and additional species. Fruit development comprises fruit set initiation, growth, and maturation and ripening. Fruit set transpires after fertilization and is associated with auxin and gibberellic acid (GA) signaling. Interaction between auxin and GAs, as well as other phytohormones, is mediated by auxin-responsive Aux/IAA and ARF proteins. Fruit growth consists of cell division and expansion, the former shown to be influenced by auxin signaling. While regulation of cell expansion is less thoroughly understood, evidence indicates synergistic regulation via both auxin and GAs, with input from additional hormones. Fruit maturation, a transitional phase that precipitates ripening, occurs when auxin and GA levels subside with a concurrent rise in abscisic acid (ABA) and ethylene. During fruit ripening, ethylene plays a clear role in climacteric fruits, whereas non-climacteric ripening is generally associated with ABA. Recent evidence indicates varying requirements for both hormones within both ripening physiologies, suggesting rebalancing and specification of roles for common regulators rather than reliance upon one. Numerous recent discoveries pertaining to the molecular basis of hormonal activity and crosstalk are discussed, while we also note that many questions remain such as the molecular basis of additional hormonal activities, the role of epigenome changes, and how prior discoveries translate to the plethora of angiosperm species.     

Deciphering the spatial-temporal transcriptional landscape of human hypothalamus development

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GABA influences the development of the ventromedial nucleus of the hypothalamus

The region that becomes the ventromedial nucleus of the hypothalamus (VMH) is surrounded by cells and fibers containing immunoreactive gamma‐aminobutyric acid (GABA) by embryonic day 13 (E13), several days before the nucleus emerges in Nissl stains. As GABA plays many roles during neural development, we hypothesized that it influences VMH development, perhaps by providing boundary information for migrating neurons. To test this hypothesis we examined the VMH in embryonic mice in which the β3 subunit of the GABA_A‐receptor, a receptor subunit that is normally highly expressed in this nucleus, was disrupted by gene targeting. In β3 ?/? embryos the VMH was significantly larger, and the distribution of cells containing immunoreactive estrogen receptor‐α was expanded compared to controls. Using in vitro brain slices from wild‐type C57BL/6J mice killed at E15 we found that treatment with the GABA_A antagonist bicuculline increased the number of cells migrating per video field analyzed in the VMH. In addition, treatment with either bicuculline or the GABA_A agonist muscimol altered the orientation of cell migration in particular regions of this nucleus. These data suggest that GABA is important for the organization of cells during VMH formation. © 2001 John Wiley & Sons, Inc. J Neurobiol 49: 264–276, 2001     

T lymphocyte development and maturation in horses

Monoclonal antibodies specific for equine T lymphocyte subpopulations were produced and procedures for the continuous culture of equine lymphocytes were developed. These reagents and procedures were used to analyse the appearance, maturation and functions of T lymphocytes in normal horses and in T lymphocyte deficient horses with severe combined immunodeficiency (SCID). T lymphocytes appeared as early as the 75th day of fetal development and were normally distributed prior to birth of normal foals. Analysis of thymic T lymphocyte differentiation in SCID foals revealed the presence of both prothymocytes and mature thymocytes, but a virtual absence of cortical thymocytes. The data obtained support the hypothesis that two distinct pathways of T lymphocyte differentiation exist within the thymus. Although the gene defect in foals with SCID blocks the production of mature B and T lymphocytes, such foals do possess large granular lymphocytes which are cytotoxic following induction with interleukin 2. This suggests that lymphoid cells with natural killer cell activity are spared by the gene defect resulting in SCID in horses.     

Ultrastructure ofAspergillus fumigatus conidia development and maturation

Summary The development and maturation of conidia of the pathogenic fungus,Aspergillus fumigatus, were studied with the electron microscope. Thin sectioning and freeze-etching techniques were employed to examine young and mature phialides, as well as developing and mature conidia. The morphological changes observed during the process of conidia formation and their maturation centered primarily around the cell wall layers and the inclusions in the cytoplasm.This investigation was supported in part by Grant #A108119 from the National Institutes of Health.     

Influence of maturation culture period on the development of canine oocytes after in vitro maturation and fertilization

The objective of this study was to determine an optimum maturation period of canine oocytes for the development in vitro after in vitro fertilization (IVF). Canine oocytes larger than 110 micrometers in diameter, which were collected from ovaries at the follicular phase of the reproductive cycle, were cultured for each time (48, 72 and 96 h) in TCM 199 medium supplemented with 10% canine serum, fertilized, and then cultured in vitro for 8 days. Significantly more oocytes reached metaphase II (MII) in the 72-h culture group than in the 48-h culture group (25.6% vs. 41.0%). The percentages of oocytes that reached MII or beyond after maturation culture did not differ significantly between the 72- and 96-h culture groups, but the percentage of parthenogenetically activated oocytes in the 96-h culture group was significantly higher than that in the 72-h culture group. The percentages of cleaved embryos after IVF were significantly higher in the 48- and 72-h culture groups than in the 96-h culture group. In the 48-h culture group, 3.9% of fertilized oocytes developed to the 16-cell stage or beyond, but none of the cleaved embryos in the 72- and 96-h culture groups developed to the same stage. These results indicate that full nuclear maturation of oocytes collected from ovaries at the follicular phase occurs after 72 h of in vitro culture. However, an optimum maturation period (48 h) for the in vitro development of canine oocytes after IVF may be different from the period necessary to reach the maximal oocyte maturation rate, when based on the developmental stage of the cleaved embryos.     

Molecular regulation of mast cell development and maturation

Mast cells play a crucial role in the pathogenesis of allergic diseases. In recent years, tremendous progresses have been made in studies of mast cell origination, migration, proliferation, maturation and survival, and the cytokines regulating these activities. These advances have significantly improved our understandings to mast cell biology and to the molecular mechanisms of mast cells in the pathogenesis of allergic diseases.     

Catecholamine-containing neurons in cultures of fetal rat hypothalamus: distribution,morphology, and maturation

The distribution, morphology, and maturation of catecholamine (CA) neurons have been studied in hypothalamic explants from late-gestation rats. CA-containing neurons were identified using the glyoxylic acid technique. CA-containing processes were present from all hypothalamic areas except the preoptic region. Several fiber types were identified. CA neurons in vitro resemble CA neurons in adult hypothalamus. This tissue culture system may be useful in the study of a number of properties of hypothalamic CA neurons.     

GABA influences the development of the ventromedial nucleus of the hypothalamus.

The region that becomes the ventromedial nucleus of the hypothalamus (VMH) is surrounded by cells and fibers containing immunoreactive gamma-aminobutyric acid (GABA) by embryonic day 13 (E13), several days before the nucleus emerges in Nissl stains. As GABA plays many roles during neural development, we hypothesized that it influences VMH development, perhaps by providing boundary information for migrating neurons. To test this hypothesis we examined the VMH in embryonic mice in which the beta3 subunit of the GABA(A)-receptor, a receptor subunit that is normally highly expressed in this nucleus, was disrupted by gene targeting. In beta3 -/- embryos the VMH was significantly larger, and the distribution of cells containing immunoreactive estrogen receptor-alpha was expanded compared to controls. Using in vitro brain slices from wild-type C57BL/6J mice killed at E15 we found that treatment with the GABA(A) antagonist bicuculline increased the number of cells migrating per video field analyzed in the VMH. In addition, treatment with either bicuculline or the GABA(A) agonist muscimol altered the orientation of cell migration in particular regions of this nucleus. These data suggest that GABA is important for the organization of cells during VMH formation.     

Transforming growth factor-alpha gene expression in the hypothalamus is developmentally regulated and linked to sexual maturation.

Hypothalamic injury causes female sexual precocity by activating luteinizing hormone-releasing hormone (LHRH) neurons, which control sexual development. Transforming growth factor-alpha (TGF-alpha) has been implicated in this process, but its involvement in normal sexual maturation is unknown. The present study addresses this issue. TGF-alpha mRNA and protein were found mostly in astroglia, in regions of the hypothalamus concerned with LHRH control. Hypothalamic TGF-alpha mRNA levels increased at times when secretion of pituitary gonadotropins--an LHRH-dependent event--was elevated, particularly at the time of puberty. Gonadal steroids involved in the control of LHRH secretion increased TGF-alpha mRNA levels. Blockade of TGF-alpha action in the median eminence, a site of glial-LHRH nerve terminal association, delayed puberty. These results suggest that TGF-alpha of glial origin is a component of the developmental program by which the brain controls mammalian sexual maturation.     

Chromatin organization in the rat hypothalamus during early development.

The organization of chromatin in neuronal and glial nuclei isolated from different brain regions of rats during development was studied by digestion of nuclei with micrococcal nuclease. A short chromatin repeat length (approx. 176 base-pairs compared with that of glial nuclei from foetal cerebral cortex (approx. 200 base-pairs) was present in hypothalamic neurons throughout the ages studied, which was similar to the repeat length of cortical neurons from 7- and 25-day-old animals (approx. 174 base-pairs). Whereas in cortical neurons the chromatin repeat length shortened from approx. 200 base-pairs in the foetus to approx. 174 base-pairs in the first postnatal week, the short chromatin repeat length of hypothalamic neurons was already present 2 days before birth, indicating that hypothalamic neurons differentiate earlier than cortical neurons during brain development.     

The development of the corticoliberin- and vasopressinergic elements of the rat hypothalamus during postnatal ontogeny

In 10--81-day and adult Wistar rats, neurosecretory cells were revealed which react with antisera to corticoliberin and vasopressin. Morphometric analysis of these cells in the supraoptic, paraventricular and anterior commissural nuclei shows that in the latter vasopressinergic cells develop somewhat later than in the supraoptic and paraventricular nuclei. Complete differentiation of neurosecretory cells in all the centres investigated is observed in 2-month animals. Studies were also made on the amount of corticoliberin- and vasopressinergic terminals in the external zone of the median eminence. Vasopressin-immunoreactive fibers are more numerous in young rats than in adult ones. Corticoliberin-positive neurosecretory fibers are more abundant in adult animals. Earlier development of vasopressinergic elements corresponds to a hypothesis of a more ancient origin of nonapeptidergic structures as compared to those producing liberins and statins.     

Targeted deletion of the sciellin gene resulted in normal development and maturation

Sciellin, together with other precursor proteins, was cross-linked by transglutaminase 1 to form the cornified envelope, an essential component of the physical barrier of the epidermis and stratified squamous epithelia. To more fully understand the function of sciellin in cornified envelope formation, we generated sciellin null mice. The mice appeared normal in their development and maturation and there were no structural features that distinguished them from littermate controls. Isolated cornified envelopes appeared normal in structure and were not more fragile to mechanical stress. There was no evidence of decreased barrier function or altered expression of other cornified envelope components. Transgenic mice expressing the repeat domain appeared to have a normal phenotype, like the null, and did not alter endogenous sciellin expression. We conclude that sciellin null mice had no structural anomalies and the transgenic mice did not act as a dominant-negative mutation.