Temporal variations of the postnatal rat urinary proteome as a reflection of systemic maturation

The rat kidney matures during the first 2 wk of life, suggesting that temporal variations in the urinary proteome may occur during this period. We describe the urine proteome during postnatal development in the rat and demonstrate specific proteomic changes corresponding to developmental milestones. Urine was collected from 30 rats at five postnatal (P) days of life (P1, P3, P7, P14, and >P30) by bladder aspiration. The proteome was assessed by nano-ESI-LC-MS/MS. For identification, we used stringent criteria to provide a 1% false positive rate at the peptide level. The proteins in common at each time interval decreased during postnatal maturation. When comparing all five developmental times, six proteins were ubiquitously present. We detected 14 proteins involved with cellular adhesion, structure, or proliferation and differentiation only during neonatal development. Additionally, 30 proteins were specific to adults, of which 13 originated from the prostate or seminal vesicle. This is the first MS characterization of the normal urinary proteome in early postnatal rodent development that demonstrates distinct differences correlating with different stages of tissue maturation. Further characterization of the normal urinary proteome may provide the basis for identification of urinary biomarkers of diseases of the urinary tract.     

Developmental shift in bidirectional functions of taurine‐sensitive chloride channels during cortical circuit formation in postnatal mouse brain

Taurine (2‐aminoethanesulfonic acid) is the most abundant free amino acid in the developing mammalian cerebral cortex, however, few studies have reported its neurobiological functions during development. In this study, by means of whole‐cell patch‐clamp recordings, we examined the effects of taurine on chloride channel receptors in neocortical neurons from early to late postnatal stages, which cover a critical period in cortical circuit formation. We show here that taurine activates chloride channels in cortical neurons throughout the postnatal stages examined (from postnatal day 2 to day 36). The physiological effects of taurine changed from excitatory to inhibitory due to variations in the intracellular Cl^? concentration during development. An antagonist blocking analysis also demonstrated a developmental shift in the receptor target of taurine, from glycine receptors to GABA_A receptors. Taken together, these results may reflect genetically programmed, bidirectional functions of taurine. At the early developmental stage, taurine acting on glycine receptors would serve to promote cortical circuit formation. As cortical circuit has to be regulated in the later stages, taurine would serve as a safeguard against hyperexcitable circuit. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 166–175, 2004     

Changes in chick liver and brain mevalonate kinase, mevalonate-5-phosphate kinase and mevalonate-5-pyrophosphate decarboxylase during development

Phosphorylation and decarboxylation of mevalonate in chick liver and brain was investigated during early post hatching stages of development. In chick liver, both mevalonate kinase and mevalonate-5-phosphate kinase increased their activity from day 5 of age while pyrophosphate decarboxylase activity remained low during the first days after hatching, increased sharply up to day 9 of age, and remained practically unchanged thereafter. The developmental pattern obtained in brain shows a slight decrease in the phosphorylation and decarboxylation of mevalonate after the first week of postnatal development. Further studies were performed using the specific substrate of mevalonate-5-pyrophosphate decarboxylase, corroborating the results obtained using mevalonate as substrate. Changes in hepatic decarboxylase were more pronounced than those observed in mevalonate-phosphorylating enzymes, thus suggesting an important role for decarboxylase in the control of cholesterogenesis during postnatal development.     

Heterochrony in the development of vestigial and functional deciduous incisors in rabbits (Oryctolagus cuniculus L.)

Foetal and postnatal development of vestigial and functional deciduous incisors was reexamined using routine serial histological sections of maxillae and mandibles at daily intervals from day 16 postconception to postnatal day 15. It was found that the development of the maxillary and mandibular vestigial incisor teeth was more rapid than that of the functional incisors and that, of the functional incisors, the maxillary posterior deciduous incisors were the slowest to develop. It appeared from this study that a basic morphogenetic requirement for unfolding structure, ie, developmental timing, was not critical in generating hypsodont or brachydont teeth. A proposition has been made that originally juvenile stages of odontogenesis represent a continuously growing system, which during evolution has successively become typical for adult descendants.     

Appearance of B and H blood group antigens in the developing cochlear hair cells

Summary The presence of human blood-group antigens was analyzed in the rat cochlea during its postnatal development, using anti-A, anti-B and anti-H antibodies. At no stage was reactivity with anti-A antibody observed. With the anti-H antibody, a strong reactivity was observed from 1 to 9 days after birth within hair cells and some other surface epithelial cells of the cochlear duct. After postnatal day 9, only a faint reactivity persisted in a few non-sensory cells. With the anti-B antibody, only hair cells were selectively labeled. At early stages (postnatal day 1 and 3), the reactivity was intense and observed both around the cell surface and within the supranuclear region of cytoplasm. Later on, the reactivity decreased; it was limited at postnatal day 9 to a reactive spot below the cuticular plate. Results are compared with a preliminary finding describing the first appearance of B and H antigens in the organ of Corti at a prenatal stage, and with data concerning other sensory and neural structures. The appearance and progressive disappearance of B and H antigens on sensory and non-sensory cells can be correlated with significant events in the development of the cochlea. The transient expression of B and H antigens in cochlear sensory cells may correspond to developmental changes in their surface glycoconjugates.     

The Expression of EPOR in Renal Cortex during Postnatal Development

Erythropoietin (EPO), known for its role in erythroid differentiation, has been shown to be an important growth factor for brain and heart. EPO is synthesized by fibroblast-like cells in the renal cortex. Prompted by this anatomical relationship and its significant impact on the maturation process of brain and heart, we asked whether EPO could play a role during the development of renal cortex. The relationship between the development of renal cortex and the change of EPO receptor (EPOR), through which EPO could act as a renotropic cytokine, became interesting to us. In this study, the day of birth was recorded as postnatal day 0(P0). P7, P14, P21, P28, P35, P42 and mature mice (postnatal days>56) were used as the animal model of different developmental stages. Immunohistochemistry and Western blotting were used to detect the expression of EPOR in mouse renal cortex. Results showed that expression of EPOR decreased with the development of renal cortex and became stable when kidney became mature. The expression of EPOR was detected at the renal tubule of all developmental stages and a relatively higher expression was observed at P14. However, at the renal corpuscle the expression was only observed at P7 and quickly became undetectable after that. All these suggested that a translocation of EPOR from renal corpuscle to renal tubule may take place during the developmental process of renal cortex. Also, EPO may be an essential element for the maturation of renal cortex, and the requirement for EPO was changed during postnatal development process.     

Ovarian development of a river catfish Hemibagrus nemurus (Valenciennes, 1840) in captivity

Hemibagrus nemurus is a riverine catfish with high economic and nutritive values. Investigations on ovarian development of this fish were carried out to determine the mode of ovarian development and describe the oocyte developmental stages. Histological studies were done on ovaries using light microscopy and scanning electron microscopy. Fish were sampled monthly for a period of six months (August 2009 to January 2010). The mean oocyte diameter (OD) ranged from 871 ± 161.41 μm to 1,167 ± 26.77 μm and the highest OD was in November. Oocyte size-frequency distribution showed a polymodal distribution. The mean gonadosomatic index (GSI) ranged from 1.14 ± 0.87% to 7.06 ± 1.40% and highest GSI was in November. The ovaries exhibited three phases of oocyte growth, which were primary growth, secondary growth and maturation phases. Based on histological criteria, the oocyte developmental stages were divided into seven stages as chromatin nucleolar, early perinucleolar, late perinucleolar, cortical alveolar, vitellogenesis, mature oocyte and germinal vesicle migration stages. All the seven stages of oocyte development were observed in the ovaries. Oogonia were always present throughout the developmental stages. The ovaries had more than two stages of oocyte development. This is the first report on the mode of ovarian development of H. nemurus. These findings indicated that H. nemurus has asynchronous mode of ovarian development and is capable of spawning several times in a year under favourable conditions.     

Developmental shift in bidirectional functions of taurine-sensitive chloride channels during cortical circuit formation in postnatal mouse brain

Taurine (2-aminoethanesulfonic acid) is the most abundant free amino acid in the developing mammalian cerebral cortex, however, few studies have reported its neurobiological functions during development. In this study, by means of whole-cell patch-clamp recordings, we examined the effects of taurine on chloride channel receptors in neocortical neurons from early to late postnatal stages, which cover a critical period in cortical circuit formation. We show here that taurine activates chloride channels in cortical neurons throughout the postnatal stages examined (from postnatal day 2 to day 36). The physiological effects of taurine changed from excitatory to inhibitory due to variations in the intracellular Cl- concentration during development. An antagonist blocking analysis also demonstrated a developmental shift in the receptor target of taurine, from glycine receptors to GABAA receptors. Taken together, these results may reflect genetically programmed, bidirectional functions of taurine. At the early developmental stage, taurine acting on glycine receptors would serve to promote cortical circuit formation. As cortical circuit has to be regulated in the later stages, taurine would serve as a safeguard against hyperexcitable circuit.     

Compositional changes in soluble proteins of cerebral mantle,cerebellum, and brain stem of rat brain during development

Soluble proteins from the cerebral mantle, cerebellum, and brain stem of rat brains were analyzed at various developmental stages by a two-dimensional gel electrophoresis technique. The electrophoretic technique resolved the soluble proteins into 100–150 polypeptide spots on two-dimensional gels and gave reproducible and highly resolved profiles of them. Although most of major polypeptides were commonly found in all the three brain regions, some polypeptides were shown to be unique to a specific brain region. Each brain region was different in the electrophoretic profile of soluble proteins at every developmental stage examined, although there was considerable similarity in the profiles of each of the three brain regions in fetal animals (16–17 days), indicating that soluble proteins undergo different compositional changes in each of the three brain regions during postnatal development. In addition, the number of polypeptide spots on the electrophoretic profile increased remarkably during postnatal development in all of the three brain regions, suggesting that soluble proteins become more heterogeneous during postnatal development in each of the three brain regions.     

Developmental changes in the biochemical and immunological characters of the carbohydrate moiety of neuroglycan C, a brain-specific chondroitin sulfate proteoglycan

Neuroglycan C (NGC), a brain-specific transmembrane proteoglycan, is thought to bear not only chondroitin sulfate but also N- and O-linked oligosaccharides on its core protein. In this study, we isolated and purified NGC from rat brains at various developmental stages by immunoaffinity column chromatography or by immunoprecipitation, and examined the structural characters of its carbohydrate moiety. The chondroitin sulfate disaccharide composition of NGC at postnatal day 10 was significantly different from those of two secreted chondroitin sulfate proteoglycans, neurocan and phosphacan, purified from the brain at the same developmental stage; higher levels of 4-sulfate unit and E unit, a disulfated disaccharide unit, and a lower level of 6-sulfate unit. The levels of both 6-sulfate and E units decreased with a compensatory increase of 4-sulfate unit with postnatal development of the brain. Lectin-blot analysis of the NGC core glycoprotein prepared by chondroitinase digestion confirmed that NGC actually bore both N- and O-linked carbohydrates, and also revealed that lectin-species reactive with NGC did not always recognize other brain-specific proteoglycans, neurocan and phosphacan, and vice versa, even though they were isolated from the brain at the same stage. The reactivity of NGC with lectins and with the HNK-1 antibody markedly changed as the brain matured. These findings indicate that the structure of the carbohydrate moiety of NGC is developmentally regulated, and differs from those of neurocan and phosphacan. The developmentally-regulated structural change of the carbohydrates on NGC may be partly implicated in the modulation of neuronal cell recognition during brain development. Published in 2004. This revised version was published online in July 2006 with corrections to the Cover Date.     

H and B human blood-group antigen expression in cochlear hair cells is modulated by thyroxine

The presence of human blood-group antigens in developing and adult hypothyroid rat cochleas was analyzed using antibodies directed against antigens H and B. During postnatal development, hypothyroid rat cochleas exhibited a highly selective expression of both B and H antigens, mainly at the hair cell level. Labeling for antigen B was found throughout the hair cells, whereas the antibody directed against antigen H selectively labeled the apical part of these cells. These immunostaining patterns were similar to those found in normal (euthyroid) rat cochleas, but antigenic expression periods were clearly prolonged. Thus, whereas in normal rat cochleas, the B and H antigenic expression disappears from postnatal day (PD) 9 on, in cochleas of hypothyroid rats the reactivity was intense until PD15; it decreased from this developmental stage, and was negative or only faintly positive at PD30. Therefore, in congenital hypothyroidism, hair cell immunoreactivity is present at developmental stages that are negative in normal rat cochleas. These results suggest that human blood-group antigen expression on the developing cochlear hair cells of rats is modulated by thyroxine and that thyroxine is necessary for the temporal expression pattern and secretion of normal glycoproteins.     

Possible organizational effect of sex steroids on the stabilization of manual preference in female common marmosets (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>)

Handedness has been widely studied in nonhuman primates. However, few studies investigate this behavior throughout ontogenetic development. To determine the influence of developmental stage in common marmoset (Callithrix jacchus) females, we used six animals, which were observed in food-reaching tests involving hand-use preference from the infantile to the adult phase. During this period, fecal samples were collected for sexual hormone analysis (estrogen and progesterone). The results point to correlations between age and stabilization of manual preference across the developmental phases. A relationship between progesterone and the intensity of hand use asymmetry was observed during the pubertal period, when the data was grouped into three phases: prepubertal, pubertal, and postpubertal. These data show increasing strength of hand preference during ontogenetic development and that sexual hormones may be involved in females.