Developmental stage-specific expression of cyclic adenosine 3',5'-monophosphate response element-binding protein CREB during spermatogenesis involves alternative exon splicing.

Spermatogenesis is a temporally regulated developmental process by which the gonadotropin-responsive somatic Sertoli and Leydig cells act interdependently to direct the maturation of the germinal cells. The metabolism of Sertoli and Leydig cells is regulated by the pituitary gonadotropins FSH and LH, which, in turn, activate adenylate cyclase. Because the cAMP-second messenger pathway is activated by FSH and LH, we postulated that the cAMP-responsive element-binding protein (CREB) plays a physiological role in Sertoli and Leydig cells, respectively. Immunocytochemical analyses of rat testicular sections show a remarkably high expression of CREB in the haploid round spermatids and, to some extent, in pachytene spermatocytes and Sertoli cells. Although most of the CREB antigen is detected in the nuclei, some CREB antigen is also present in the cytoplasm. Remarkably, the cytoplasmic CREB results from the translation of a unique alternatively spliced transcript of the CREB gene that incorporates an exon containing multiple stop codons inserted immediately up-stream of the exons encoding the DNA-binding domain of CREB. Thus, the RNA containing the alternatively spliced exon encodes a truncated transcriptional transactivator protein lacking both the DNA-binding domain and nuclear translocation signal of CREB. Most of the CREB transcripts detected in the germinal cells contain the alternatively spliced exon, suggesting a function of the exon to modulate the synthesis of CREB. In the Sertoli cells we observed a striking cyclical (12-day periodicity) increase in the levels of CREB mRNA that coincides with the splicing out of the restrictive exon containing the stop codons. Because earlier studies established that FSH-stimulated cAMP levels in Sertoli cells are also cyclical, and the CREB gene promoter contains cAMP-responsive enhancers, we suggest that the alternative RNA splicing controls a positive autoregulation of CREB gene expression mediated by cAMP.

Similarities and dissimilarities between the Movement ABC-2 and the Zurich Neuromotor Assessment in children with suspected developmental coordination disorder.

An established tool for the assessment of motor performance in children with developmental coordination disorder (DCD) is the Movement-ABC-2 (M-ABC-2). The Zurich Neuromotor Assessment (ZNA) is also widely used for the evaluation of children's motor performance, but has not been compared with the M-ABC-2. Fifty-one children (39 males) between 5 and 7 years of age with suspected DCD were assessed using the M-ABC-2 and the ZNA. Rank correlations between scores of different test components were calculated. The structure of the tests was explored using canonical-correlation analysis. The correlation between total scores of the two motor tests was reasonable (0.66; p<0.001). However, ZNA scores were generally lower than those of M-ABC-2, due to poor performance in the fine motor adaptive component and increased contralateral associated movements (CAM). The canonical-correlation analysis revealed that ZNA measures components like pure motor skills and CAM that are not represented in the M-ABC-2. Furthermore, there was also no equivalent for the aiming and catching items of the M-ABC-2 in ZNA. The two tests measure different motor characteristics in children with suspected DCD and, thus, can be used complementary for the diagnosis of the disorder.

Causes développementales dans la variabilité de l'efficacité et de la toxicité des antalgiques en pédiatrie [Developmental causes in variability of efficacy and toxicity of analgesics in pediatrics]

The intensity of pain perception and its sensibility to analgesic drugs is highly variable and unpredictable between individuals. Drug disposition varies during development due to the physiological maturation of enzymatic systems and physiological processes responsible for the absorption, distribution, elimination and effect at the site of action. Many of those developmental variables are not yet clearly defined, but their consideration is important for avoiding potential risks of ineffective or toxic treatment. Implications of those developmental changes for day-to-day clinical practice depend on the age of the child, on the type of drug, on the underlying disease and on the potential co-administration of other chemicals.

Transitory glutathione deficit during brain development induces cognitive impairment in juvenile and adult rats: relevance to schizophrenia.

Glutathione (GSH) metabolism dysfunction is one risk factor in schizophrenia. A transitory brain GSH deficit was induced in Wistar (WIS) and mutant (ODS; lacking ascorbic acid synthesis) rats using BSO (l-buthionine-(S,R)-sulfoximine) from post-natal days 5-16. When GSH was re-established to physiological levels, juvenile BSO-ODS rats were impaired in the water maze task. Long after treatment cessation, adult BSO-WIS/-ODS rats showed impaired place discrimination in the homing board with distributed visual or olfactory cues. Their accuracy was restored when a single cue marked the trained position. Similarly, more working memory errors were made by adult BSO-WIS in the radial maze when several olfactory cues were present. These results reveal that BSO rats did not suffer simple sensory impairment. They were selectively impaired in spatial memory when the task required the integration of multimodal or olfactory cues. These results, in part, resemble some of the reported olfactory discrimination and cognitive impairment in schizophrenia.

Developmental change in isoproterenol-mediated relaxation of pulmonary veins of fetal and newborn lambs.

beta-Adrenergic agonists are important regulators of perinatal pulmonary circulation. They cause vasodilation primarily via the adenyl cyclase-adenosine 3',5'-cyclic monophosphate (cAMP) pathway. We examined the responses of isolated fourth-generation pulmonary veins of term fetal (145 +/- 2 days gestation) and newborn (10 +/- 1 days) lambs to isoproterenol, a beta-adrenergic agonist. In vessels preconstricted with U-46619 (a thromboxane A2 analog), isoproterenol induced greater relaxation in pulmonary veins of newborn lambs than in those of fetal lambs. The relaxation was eliminated by propranolol, a beta-adrenergic antagonist. Forskolin, an activator of adenyl cyclase, also caused greater relaxation of veins of newborn than those of fetal lambs. 8-Bromoadenosine 3',5'-cyclic monophosphate, a cell membrane-permeable analog of cAMP, induced a similar relaxation of all vessels. Biochemical studies show that isoproterenol and forskolin induced a greater increase in cAMP content and in adenyl cyclase activity of pulmonary veins in the newborn than in the fetal lamb. These results demonstrate that beta-adrenergic-agonist-mediated relaxation of pulmonary veins increases with maturation. An increase in the activity of adenyl cyclase may contribute to the change.

Developmental and Environmental Regulation of Aquaporin Gene Expression across Populus Species: Divergence or Redundancy?

Aquaporins (AQPs) are membrane channels belonging to the major intrinsic proteins family and are known for their ability to facilitate water movement. While in Populus trichocarpa, AQP proteins form a large family encompassing fifty-five genes, most of the experimental work focused on a few genes or subfamilies. The current work was undertaken to develop a comprehensive picture of the whole AQP gene family in Populus species by delineating gene expression domain and distinguishing responsiveness to developmental and environmental cues. Since duplication events amplified the poplar AQP family, we addressed the question of expression redundancy between gene duplicates. On these purposes, we carried a meta-analysis of all publicly available Affymetrix experiments. Our in-silico strategy controlled for previously identified biases in cross-species transcriptomics, a necessary step for any comparative transcriptomics based on multispecies design chips. Three poplar AQPs were not supported by any expression data, even in a large collection of situations (abiotic and biotic constraints, temporal oscillations and mutants). The expression of 11 AQPs was never or poorly regulated whatever the wideness of their expression domain and their expression level. Our work highlighted that PtTIP1;4 was the most responsive gene of the AQP family. A high functional divergence between gene duplicates was detected across species and in response to tested cues, except for the root-expressed PtTIP2;3/PtTIP2;4 pair exhibiting 80% convergent responses. Our meta-analysis assessed key features of aquaporin expression which had remained hidden in single experiments, such as expression wideness, response specificity and genotype and environment interactions. By consolidating expression profiles using independent experimental series, we showed that the large expansion of AQP family in poplar was accompanied with a strong divergence of gene expression, even if some cases of functional redundancy could be suspected.

Workgroup report: incorporating in vitro alternative methods for developmental neurotoxicity into international hazard and risk assessment strategies.

This is the report of the first workshop on Incorporating In Vitro Alternative Methods for Developmental Neurotoxicity (DNT) Testing into International Hazard and Risk Assessment Strategies, held in Ispra, Italy, on 19-21 April 2005. The workshop was hosted by the European Centre for the Validation of Alternative Methods (ECVAM) and jointly organized by ECVAM, the European Chemical Industry Council, and the Johns Hopkins University Center for Alternatives to Animal Testing. The primary aim of the workshop was to identify and catalog potential methods that could be used to assess how data from in vitro alternative methods could help to predict and identify DNT hazards. Working groups focused on two different aspects: a) details on the science available in the field of DNT, including discussions on the models available to capture the critical DNT mechanisms and processes, and b) policy and strategy aspects to assess the integration of alternative methods in a regulatory framework. This report summarizes these discussions and details the recommendations and priorities for future work.

Juvenile antioxidant treatment prevents adult deficits in a developmental model of schizophrenia.

Abnormal development can lead to deficits in adult brain function, a trajectory likely underlying adolescent-onset psychiatric conditions such as schizophrenia. Developmental manipulations yielding adult deficits in rodents provide an opportunity to explore mechanisms involved in a delayed emergence of anomalies driven by developmental alterations. Here we assessed whether oxidative stress during presymptomatic stages causes adult anomalies in rats with a neonatal ventral hippocampal lesion, a developmental rodent model useful for schizophrenia research. Juvenile and adolescent treatment with the antioxidant N-acetyl cysteine prevented the reduction of prefrontal parvalbumin interneuron activity observed in this model, as well as electrophysiological and behavioral deficits relevant to schizophrenia. Adolescent treatment with the glutathione peroxidase mimic ebselen also reversed behavioral deficits in this animal model. These findings suggest that presymptomatic oxidative stress yields abnormal adult brain function in a developmentally compromised brain, and highlight redox modulation as a potential target for early intervention.

Shift of spawning season and effects of climate warming on developmental stages of a grayling (Salmonidae)

River-dwelling fish, such as European graylings (Thymallus thymallus), are susceptible to changes in climate because they can often not avoid suboptimal temperatures, especially during early developmental stages. We analyzed data collected in a 62-year-long (1948-2009) population monitoring program. Male and female graylings were sampled about three times/week during the yearly spawning season in order to follow the development of the population. The occurrence of females bearing ripe eggs was used to approximate the timing of each spawning season. In the last years of the study, spawning season was more than 3 weeks earlier than in the first years. This shift was linked to increasing water temperatures as recorded over the last 39 years with a temperature logger at the spawning site. In early spring water temperatures rose more slowly than in later spring. Thus, embryos and larvae were exposed to increasingly colder water at a stage that is critical for sex determination and pathogen resistance in other salmonids. In summer, however, fry were exposed to increasingly warmer temperatures. The changes in water temperatures that we found embryos, larvae, and fry were exposed to could be contributing to the decline in abundance that has occurred over the last 30-40 years.

Triiodothyronine stimulation of oligodendroglial differentiation and myelination. A developmental study.

The biochemical development of rotation-mediated aggregating brain cell cultures was studied in a serum-free chemically defined medium in the presence (complete medium) or the absence of triiodothyronine (T3). The expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) and myelin basic protein (MBP), two myelin components, was temporally dissociated in brain cell aggregating cultures grown in a complete medium. CNP increased from day 8 and reached a plateau around day 25. MBP accumulated rapidly from the third until the fourth week in culture. The total protein content increased gradually until day 25. The activity of ornithine decarboxylase (ODC) used as an index of cell growth and differentiation, showed two well-defined peaks of activity. The first peak reached a maximum at day 6 and correlated with both the highest DNA content and the peak of [3H]-thymidine incorporation. The second peak of ODC activity (from day 19 to 35) coincided with the differentiation of oligodendrocytes. These results confirm that aggregating fetal rat brain cells cultured in a serum-free chemically defined medium undergo extensive differentiation. Addition of T3 to the culture medium doubled the CNP activity by day 16. In contrast, MBP was only slightly increased by day 16, reaching at 25 and 35 days 8 to 10-fold higher values than the untreated cultures. When T3 was removed between day 16 and 25, CNP decreased almost to control values and MBP failed to accumulate. Moreover, when T3 was reintroduced into the medium (between day 25 and 35), CNP activity was restored and MBP content was partially corrected. T3 treatment produced a concentration-dependent increase in ODC activity which was observed only around day 19. The first peak of ODC activity observed at culture day 6 was independent of the presence of T3. These results obtained in brain cell cultures emphasize the direct effect of T3 on myelination.