Expression of steroid sulfatase during embryogenesis

Neurosteroids are steroids that are synthesized de novo in the brain from cholesterol and, in general, mediate their effects through ion-gated channel receptors such as gamma-aminobutyric acidA (GABA[A]) and N-methyl-D-aspartate receptors rather than through classical nuclear steroid hormone receptors. Steroid hormones are known to exist not only as free compounds, but also as sulfated derivatives. Pharmacological studies indicate that unconjugated and sulfated steroids, such as pregnenolone and pregnenolone sulfate, may have opposite effects on GABA(A) receptors. Thus, pregnenolone acts as a potent positive allosteric modulator of gamma-aminobutyric acid action at GABA(A )receptors, whereas pregnenolone sulfate acts as a potent negative modulator. Recent experiments also suggest that dehydroepiandrosterone and dehydroepiandrosterone sulfate may have distinct effects on growth of neurites from embryonic neocortical neurons in vitro. Thus, regulation of steroid sulfation may have profound behavioral and morphological effects on the nervous system. We, therefore, studied the developmental expression of the enzyme steroid sulfatase (STS), which converts sulfated steroids to free steroids. By in situ hybridization, STS messenger RNA was expressed in the embryonic mouse cortex, hindbrain, and thalamus during the last third of gestation. The sites of expression of STS were similar to those of P450c17, suggesting that these two enzymes may have concerted actions in similar functional processes.     

Temporal pattern of IGF-I expression during mouse preimplantation embryogenesis

PURPOSE: To evaluate the role of casual and exercise blood pressure as well as the importance of clinical factors on the presence and degree of left ventricular hypertrophy in hypertension. METHODS: Fifteen normotensives (control group) and 30 hypertensives, 14 of them with and 16 without left ventricular hypertrophy (groups with LVH and without LVH, respectively) were studied. LVH diagnosis was established when mass index was higher than 2 standard-deviations of the mean values calculated for each sex in control group. Resting, casual determined, and bicycle exercise systolic and diastolic blood pressures along with age, body surface area, sex and race distribution were compared between groups. In addiction, their relation with mass index as independent variables were also tested. RESULTS: Hypertensives in group with LVH had higher diastolic septal, posterior wall, and relative wall thicknesses. No significant statistical difference was observed neither in sex and race distribution, nor in age and body surface area between groups. Otherwise, there were significant differences in both resting and exercise blood pressure. In the entire population studied, left ventricular mass index significantly correlated with age (r=0,33, p=0,03) as well as with both casual (systolic - r=0,72, p=0,0001; diastolic - r=0,69, p=0,0001) and exercise (systolic - r=0,62, p=0,0001; diastolic - r=0,66, p=0,0001) blood pressures. However, linear regression analysis demonstrated that only resting systolic (p=0,0001) and exercise diastolic (p=0,0303) blood pressures were significant and independent determinants of mass index. CONCLUSION: Resting and exercising blood pressures are the main determinants of left ventricular hypertrophy in hypertension.     

A zebrafish Id homologue and its pattern of expression during embryogenesis

Schistosoma mansoni is known to be unable to synthesize fatty acids and sterols de novo, but the parasite is capable of synthesizing phospholipids and triacylglycerols from precursors obtained from the host. The present study focuses on the dynamics of the incorporation of fatty acids in adult parasites. This study showed that fatty acids were rapidly metabolized into complex lipids and that oleate (18:1) was efficiently converted to eicosenoate (20:1) by chain elongation, whereas palmitate was not elongated at an appreciable rate. This chain elongation mainly involved fatty acids that were previously esterified to complex lipids. Furthermore it was shown that in adult parasites triacylglycerols do not serve as fatty-acyl donors in phospholipid synthesis as had been suggested to be the case in schistosomula, because: (1) Immediately after pulse-labelling the specific activity of fatty acids in phospholipids was higher than in triacylglycerols; and (2) the specific activity of eicosenoate, which had been formed by chain elongation of incorporated oleate. was higher in phospholipids than in triacylglycerols. Fatty acids that were esterified to phospholipids had a high turnover, in contrast to fatty acids esterified to triacylglycerols, which persisted for extended periods of time in this lipid class (days rather than hours).     

Temporal and spatial pattern of expression of the HDL receptor SR-BI during murine embryogenesis

Cerebellar long-term depression (LTD) is a model system for neuronal information storage that has an absolute requirement for activation of protein kinase C (PKC). It has been claimed to underlie several forms of cerebellar motor learning. Previous studies using various knockout mice (mGluR1, GluRdelta2, glial fibrillary acidic protein) have supported this claim; however, this work has suffered from the limitations that the knockout technique lacks anatomical specificity and that functional compensation can occur via similar gene family members. To overcome these limitations, a transgenic mouse (called L7-PKCI) has been produced in which the pseudosubstrate PKC inhibitor, PKC[19-31], was selectively expressed in Purkinje cells under the control of the pcp-2(L7) gene promoter. Cultured Purkinje cells prepared from heterozygous or homozygous L7-PKCI embryos showed a complete blockade of LTD induction. In addition, the compensatory eye movements of L7-PKCI mice were recorded during vestibular and visual stimulation. Whereas the absolute gain, phase, and latency values of the vestibulo-ocular reflex and optokinetic reflex of the L7-PKCI mice were normal, their ability to adapt their vestibulo-ocular reflex gain during visuo-vestibular training was absent. These data strongly support the hypothesis that activation of PKC in the Purkinje cell is necessary for cerebellar LTD induction, and that cerebellar LTD is required for a particular form of motor learning, adaptation of the vestibulo-ocular reflex.     

The dissociation rate of a winged helix protein-DNA complex is influenced by non-DNA contact residues

The dissociation constants and the half-lives of the DNA complexes of winged helix protein Genesis and its mutants were investigated. Our data show that substitutions of non-DNA contact residues in the two highly dynamic wing sequences dramatically change the off rates of the complexes. Thus, our data indicate that the off rate of a DNA complex is encoded in the amino acid sequence of the DNA-binding protein and/or should be a unique property for a protein-DNA complex. Our data also indicate that the local structural transition of a DNA-binding protein in its DNA recognition process is likely to go through a transition state, which can control the on and off rates of a complex.     

Role of fibroblast growth factor during early midbrain development in Xenopus

Genes encoding fibroblast growth factors (FGFs) are expressed in early Xenopus neurulae in the prospective midbrain-hindbrain boundary (MHB) region of the neural plate. These expression domains overlap those of XWnt-1 and XEn-2, raising the question of the role of FGF signalling in the regulation of these genes, and more generally about the function of FGF during Xenopus midbrain development. We report that explants from the prospective MHB grafted into the anterior neural plate in midneurula stage embryos induce XWnt-1 expression and, at a lower frequency, XEn-2 expression in the vicinity of the graft. Such a process is likely to involve FGF signalling. Implantation of FGF4- or FGF8-soaked beads in the prospective forebrain at neurula and tailbud stages causes the up-regulation of XWnt-1 and XEn-2 in the dorsal and lateral region of the anterior midbrain. This effect is not relayed by endogenous FGF genes since exogenous FGFs inhibit the expression of endogenous XFGF3 or XFGF8. However, consequences of grafting MHB or implanting FGF4 or FGF8 beads on tadpole brain development are different. MHB grafts induce ectopic mesencephalic structures, strongly suggesting that a region homologous to the isthmic organizer of amniotes is specified as early as the midneurula stage. In contrast, exogenous FGFs do not cause the formation of ectopic mesencephalic structures but an overgrowth of mesencephalon and diencephalon. We propose that FGF signals from the prospective MHB play a crucial role in the spatial regulation of XWnt-1 and XEn-2 expression in the posterior midbrain, but that the full organizing activity of the MHB involves other factors in combination with FGF.     

Structural changes in the region directly adjacent to the DNA-binding helix highlight a possible mechanism to explain the observed changes in the sequence-specific binding of winged helix proteins

BACKGROUND: Endotoxaemia is implicated in the pathophysiology of obstructive jaundice. The EndoCab enzyme linked immunosorbent assay (ELISA) is a novel assay which measures endogenous antibody (IgG) to the inner core region of circulating endotoxins (ACGA). AIMS: To investigate the significance of endotoxaemia in biliary obstruction using the EndoCab assay and assess the specificity of the humoral response to endotoxin compared with an exogenous antigenic challenge (tetanus toxoid, TT). METHODS: Three groups of adult male Wistar rats were studied: no operation, sham operation, and bile duct ligation for 21 days (BDL). In the second study, rats rats received prior immunisation with TT. RESULTS: In the preliminary experiment, plasma ACGA was significantly increased in the BDL group (306.6 (18.3)% versus 119.9 (6.7)% and 105.2 (4.6)% in the sham and no operation groups, respectively; p < 0.001). Although the mean endotoxin concentration in the BDL group was greater than that in the control groups this was not significant. There was a strong positive correlation between ACGA and endotoxin concentrations (p = 0.0021). In the second study mean ACGA after 21 days of BDL was significantly elevated (267.1 (31.2)% versus 101.6 (21.2)% at baseline, p < 0.0001). ACGA was unaffected in the other two groups. TT antibody concentrations fell in all three groups; only in the BDL group was the fall significant (97.6 (5.3)% versus 78.8 (4.2)% at baseline, p < 0.05). CONCLUSIONS: The specific rise in ACGA supports the hypothesis that endotoxin has an integral role in the pathophysiology of obstructive jaundice. The production of anticore glycolipid antibodies specifically reflects systemic endotoxaemia in this model. The EndoCab assay provides a novel, sensitive, and specific method for endotoxin detection.     

Isolation of a gene expressed during early embryogenesis from the region of 22q11 commonly deleted in DiGeorge syndrome

DiGeorge syndrome (DGS) is one of several syndromes associated with deletions within the proximal long-arm of chromosome 22. The region of chromosome 22q11 responsible for the haploinsufficiency syndromes (the DiGeorge Critical Region or DGCR) has been mapped using RFLPs, quantitative Southern blotting and FISH. Similar deletions are seen in the velo-cardio-facial syndrome (VCFS) and familial congenital heart defects. It is not known whether the phenotypic spectrum is the result of the hemizygosity of one gene or whether it is a consequence of contiguous genes being deleted. However, the majority of patients have a large (> = 2Mb deletion). In this paper we report the isolation of a gene, lab name T10, encoding a serine/threonine rich protein of unknown function which maps to the commonly deleted region of chromosome 22q11. Studies in the mouse indicate that it maps to MMU16 and is expressed during early embryogenesis. Although not mapping within the shortest region of overlap for DGS/VCFS, and therefore not the major gene involved in DGS, the expression pattern suggests that this gene may be involved in modifying the haploinsufficient phenotype of hemizygous patients.     

Chicken winged-helix transcription factor cFKH-1 prefigures axial and appendicular skeletal structures during chicken embryogenesis

OBJECTIVE: To determine whether hyperandrogenism in anovulatory women affects body fat distribution. DESIGN: Prospective nonrandomized study. SETTING: An academic research environment. PATIENT(S): Ten hyperandrogenic anovulatory patients and 10 healthy women matched by body mass index. INTERVENTION(S): Regional body fat analysis was performed before and after 3 months of GnRH analogue (GnRH-a) therapy. MAIN OUTCOME MEASURE(S): Body fat distribution was measured by waist-to-hip circumference ratio, single-slice computed tomography imaging (L2-3 interspace), and total body dual-energy x-ray absorptiometry. RESULT(S): Weight, body mass index, waist-to-hip circumference ratio, total body and leg fat mass, and subcutaneous adipose area were unaffected by the presence of hyperandrogenism or the use of GnRH-a therapy. Basal abdominal fat mass, abdomen-to-leg fat mass ratio, visceral adipose area, and total visceral adipose volume were comparable in both study groups. The abdominal fat mass increased in both groups during GnRH-a therapy, whereas the abdomen-to-leg fat mass ratio rose significantly only in the hyperandrogenic patients. During GnRH-a therapy, the hyperandrogenic patients demonstrated a significant increase in visceral adipose area compared with the healthy women so that total visceral adipose volume increased significantly in the former but not the latter. CONCLUSION(S): Three months of GnRH-a administration preferentially increased abdominal fat, as measured by single-slice computed tomography imaging and total body dual-energy x-ray absorptiometry, in hyperandrogenic anovulatory women.