Distribution and acute stressor-induced activation of corticotrophin-releasing hormone neurones in the central nervous system of Xenopus laevis.

In mammals, corticotrophin-releasing hormone (CRH) and related peptides are known to play essential roles in the regulation of neuroendocrine, autonomic and behavioural responses to physical and emotional stress. In nonmammalian species, CRH-like peptides are hypothesized to play similar neuroendocrine and neurocrine roles. However, there is relatively little detailed information on the distribution of CRH neurones in the central nervous system (CNS) of nonmammalian vertebrates, and there are currently no comparative data on stress-induced changes in CRH neuronal physiology. We used a specific, affinity-purified antibody raised against synthetic Xenopus laevis CRH to map the distribution of CRH in the CNS of juvenile South African clawed frogs. We then analysed stress-induced changes in CRH immunoreactivity (CRH-ir) throughout the CNS. We found that CRH-positive cell bodies and fibres are widely distributed throughout the brain and rostral spinal cord of juvenile X. laevis. Strong CRH-immunoreactivity (ir) was found in cell bodies and fibres in the anterior preoptic area (POA, an area homologous to the mammalian paraventricular nucleus) and the external zone of the median eminence. Specific CRH-ir cell bodies and fibres were also identified in the septum, pallium and striatum in the telencephalon; the amygdala, bed nucleus of the stria terminalis and various hypothalamic and thalamic nuclei in the diencephalon; the tectum, torus semicircularis and tegmental nuclei of the mesencephalon; the cerebellum and locus coeruleus in the rhombencephalon; and the ventral horn of the rostral spinal cord. To determine if exposure to an acute physical stressor alters CRH neuronal physiology, we exposed juvenile frogs to shaking/handling and conducted morphometric analysis. Plasma corticosterone was significantly elevated by 30 min after exposure to the stressor and continued to increase up to 6 h. Morphometric analysis of CRH-ir after 4 h of stress showed a significant increase in CRH-ir in parvocellular neurones of the anterior preoptic area, the medial amygdala and the bed nucleus of the stria terminalis, but not in other brain regions. The stress-induced increase in CRH-ir in the POA was associated with increased Fos-like immunoreactivity (Fos-LI), and confocal microscopy showed that CRH-ir colocalized with Fos-LI in a subset of Fos-LI-positive neurones. Our results support the view that the basic pattern of CNS CRH expression arose early in vertebrate evolution and lend further support to earlier studies suggesting that amphibians may be a transitional species for descending CRH-ergic pathways. Furthermore, CRH neurones in the frog brain exhibit changes in response to a physical stressor that parallel those seen in mammals, and thus are likely to play an active role in mediating neuroendocrine, behavioural and autonomic stress responses.

Development of a human DNA quantitation system.

The AluQuant Human DNA Quantitation System has been developed for human-specific quantitation of forensic samples. This system uses probes specific to repetitive genetic elements allowing quantitation without target amplification. Target immobilization is unnecessary with employment of solution hybridization. The AluQuant Human DNA Quantitation System uses a series of enzymatic reactions to produce a luminescent signal proportional to the quantity of human DNA present. This report demonstrates a range of quantitation from 0.1-50 ng of human DNA. Signal from non-human DNAs tested was insignificant and addition of non-human DNAs into a human sample did not alter quantitation. Lastly, the system was unaffected by degradation of sample through sonication. The AluQuant Human DNA Quantitation System is a simple and sensitive method for quantitating the concentration of human DNA in forensic samples.

[Variation of the sialic acid-protein ratio in the human cervical mucus (author's transl)]. / Variación de la relación del ácido siálico y protéina en el moco cervical humano

Serial determinations of total protein and sialic acid concentrations were carried out in individual cervical mucus samples of normal women, throughout the menstrual cycle as well as under the influence of estrogen and progestagen steroids. Total protein was titrated by a modified micro-biuret method and sialic acid was determined using the "Direct Ehrlich" method. Both parameters diminished gradually during the follicular phase of the cycle with lowest values around the time of ovulation, and showed a strong increase during the luteal phase. Administration of ethinylestradiol yielded values significantly lower than those of normal ovulatory phase and under d-Nosgestrel treatment the values were significantly higher than in normal luteal phase. However the proportion of sialic acid as related to total protein showed an inverse behavior, i.e. increased under estrogenic and decreased under progestogenic influence. The cyclic and hormone-induced variations of this ratio were more specific than those of both separate components. Thus, estrogens produce an increase of the sialic acid containing fraction of cervical mucus proteins, while progestagens have an opposite effect. The role of these actions in reproductive physiology is discussed.