Ontogenetic development of corticotropin-releasing factor (CRF)-containing neural elements in the brain of the chicken during incubation and after hatching

Summary In chicken embryos of different ages and in young chickens after hatching, neural elements reacting with antibodies generated against synthetic ovine corticotropin-releasing factor (CRF) were studied by means of the peroxidase-anti-peroxidase (PAP) technique at the lightmicroscopic level. CRF-immunoreactivity was first observed in perikarya located in the periventricular part of the hypothalamus on the 14th day of the incubation period. CRF-containing neural elements were detected on the same day of incubation in the external zone of the median eminence, but not in all investigated animals. In extrahypothalamic sites, immunoreactive perikarya were demonstrable in the central gray of the mesencephalon on the 15th day of incubation. Furthermore, immunoreactive cells appeared in other brain regions such as nucleus accumbens and dorsomedial nucleus of the thalamus after hatching. The present observations provide information regarding the functional development of the hypothalamo-hypophyseal-adrenal axis in the chick embryo.     

Localization of corticotropin-releasing factor-containing neurons in the brain of the domestic fowl

Summary The corticotropin-releasing factor (CRF)-containing neurons were investigated in the brain of the domestic fowl by means of the peroxidase-antiperoxidase technique at the light-microscopic level. The detection of CRF-immunoreactivity was facilitated by silver intensification. CRF-containing perikarya were found in the paraventricular, preoptic and mammillary nuclei of the hypothalamus and in some extrahypothalamic areas (nuclei dorsomedialis and dorsolateralis thalami, nucleus accumbens septi, lobus parolfactorius, periaqueductal gray of the mesencephalon, nucleus oculomotorius ventralis). Immunoreactive nerve fibers and terminals were demonstrated in the external zone of the median eminence and the organum vasculosum of the lamina terminalis. These results indicate that an immunologically demonstrable CRF-neurosecretory system also exists in the avian central nervous system.     

Effect of the fungal toxin (zearalenone) on the reproductive system and fertility of male and female rats.

The fertility-inhibiting effects of long-term (8 weeks) consumption of maize infected with a fungus producing F2 toxin (zearalenone) was studied in adult male and female albino rats. The fertility rate was further decreased by 25-30% if the animals were kept on contaminated diet up to 14 weeks. The gonadal weight was decreased, follicular maturation and spermatogenesis were disturbed. The toxic diet consumed by mothers during pregnancy and lactation induced permanent changes in reproductive organs, disorders in vaginal cyclicity and disturbed fertility in the offspring. Neonatal administration of purified F2 toxin provoked similar changes. It is suggested that this fungal toxin may cause sterility syndrome in the offspring, similar to that produced by androgen or estrogen administration.     

Intercellular communication in the rat anterior pituitary gland: an in vivo and in vitro study

The concept of "stimulus-secretion coupling" suggested by Douglas and co-workers to explain the events related to monamine discharge by the adrenal medulla (5, 7) may be applied to other endocrine tissues, such as adrenal cortex (36), pancreatic islets (4), and magnocellular hypothalamic neurons (6), which exhibit a similar ion-dependent process of hormone elaboration. In addition, they share another feature, that of joining neighbor cells via membrane junctions (12, 26, and Fletcher, unpublished observation). Given this, and the reports that hormone secretion by the pars distalis also involves a secretagogue-induced decrease in membrane bioelectric potential accompanied by a rise in cellular [Ca++] (27, 34, 41), it was appropriate to test the possibility that cells of the anterior pituitary gland are united by junctions.     

Role of the serotoninergic neuron system of the brain stem on the release of thyrotrophic and luteinizing hormone

1. Decrease of brain serotonin concentration, elicited by either parachlorophenylalanine treatment, surgical interruption of the ascending serotoninergic fibres, or by pinealectomy provokes an enhanced release both of TSH and LH. 2. Increased serotonin content of the brain, produced by intraventricular, intrahypothalamic or systemic administration of serotonin, results in a significant inhibition of the release of these two trophic hormones. 3. It is concluded that the serotoninergic neuron system of the brain stem represents an inhibitory mechanism in the neuroendocrine circuit regulating pituitary trophic hormone release.     

Conservation of placentation during the tertiary radiation of mammals in South America

The eutherian placenta is considered to possess great plasticity, but it is not clear how this variation reflects adaptation to different ecological niches. Because South America was isolated for most of the Tertiary, it represents a natural laboratory to examine this question. We here describe placentation in three South American groups: Xenarthra have been part of the fauna from at least the mid‐Paleocene whereas caviomorph rodents and Neotropical primates are each derived from a single founder that reached South America in the Eocene and Oligocene, respectively. The common ancestor of Xenarthra had a villous, haemochorial placenta, from which the labyrinthine, endotheliochorial placenta of sloths later evolved. Placentation in Caviomorpha follows an extraordinary stable pattern, characterized by a haemomonochorial, labyrinthine and highly lobed structure with specialized growing areas. This pattern was present before arrival of these rodents in South America and enabled a successful radiation especially during the spread of grasslands. Neotropical primates have haemochorial, trabecular placentas with a specialized maternal blood supply; a pattern that contrasts with that of Old World monkeys and may have been present in the founder generation on arrival in South America. In conclusion, there is a dichotomy within Xenarthra but otherwise the ancient South American mammals do not show much variation in principal placental characters. Thus, the successful radiation of these three groups, and their adaptation to diverse ecological niches, did not require substantial alterations in placentation. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Classification and nomenclature of all human homeobox genes

Background

The homeobox genes are a large and diverse group of genes, many of which play important roles in the embryonic development of animals. Increasingly, homeobox genes are being compared between genomes in an attempt to understand the evolution of animal development. Despite their importance, the full diversity of human homeobox genes has not previously been described.

Results

We have identified all homeobox genes and pseudogenes in the euchromatic regions of the human genome, finding many unannotated, incorrectly annotated, unnamed, misnamed or misclassified genes and pseudogenes. We describe 300 human homeobox loci, which we divide into 235 probable functional genes and 65 probable pseudogenes. These totals include 3 genes with partial homeoboxes and 13 pseudogenes that lack homeoboxes but are clearly derived from homeobox genes. These figures exclude the repetitive DUX1 to DUX5 homeobox sequences of which we identified 35 probable pseudogenes, with many more expected in heterochromatic regions. Nomenclature is established for approximately 40 formerly unnamed loci, reflecting their evolutionary relationships to other loci in human and other species, and nomenclature revisions are proposed for around 30 other loci. We use a classification that recognizes 11 homeobox gene 'classes' subdivided into 102 homeobox gene 'families'.

Conclusion

We have conducted a comprehensive survey of homeobox genes and pseudogenes in the human genome, described many new loci, and revised the classification and nomenclature of homeobox genes. The classification scheme may be widely applicable to homeobox genes in other animal genomes and will facilitate comparative genomics of this important gene superclass.     

Characterization of terminal NeuNAcalpha2-3Galbeta1-4GlcNAc sequence in lipooligosaccharides of Neisseria meningitidis

Group B and C Neisseria meningitidis are the major cause of meningococcal disease in the United States and in Europe. N . meningitidis lipooligosaccharide (LOS), a major surface antigen, can be divided into 12 immunotypes of which L1 through L8 were found among Group B and C organisms. Groups B and C but not Group A may sialylate their LOSs with N-acetylneuraminic acid (NeuNAc) at the nonreducing end because they synthesize CMP-NeuNAc. Using sialic acid-galactose binding lectins as probes in an ELISA format, six of the eight LOS immunotypes (L2, L3, L4, L5, L7, and L8) in Groups B and C bound specifically to Maackia amurensis leukoagglutinin (MAL), which recognizes NeuNAcalpha2- 3Galbeta1-4GlcNAc/Glc sequence, but not to Sambucus nigra agglutinin, which binds NeuNAcalpha2-6Gal sequence. The combination of SDS-PAGE and MAL-blot analyses revealed that these six LOSs contained only the NeuNAcalpha2-3Galbeta1-4GlcNAc trisaccharide sequence in their 4.1 kDa LOS components, which have a common terminal lacto-N-neotetraose (LNnT, Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) structure when nonsialylated as shown by previous studies. The LOS-lectin binding was abolished when the LOSs were treated with Newcastle disease viral neuraminidase which cleaves alpha2-->3 linked sialic acid. Methylation analysis of a representative LOS (L2) confirmed that NeuNAc is 2-->3 linked to Gal. Thus, these LOSs structurally mimic certain glycolipids, i.e., paragloboside (LNnT-ceramide) and sialylparagloboside and some glycoproteins in having LNnT and N-acetyllactosamine sequences, respectively, with or without alpha2-->3 linked NeuNAc. The molecular mimicry of the LOSs may play a role in the pathogenesis of N.meningitidis by assisting the organism to evade host immune defenses in man.      

Protocol of a prospective study on the diagnostic value of transcranial duplex scanning of the substantia nigra in patients with parkinsonian symptoms

Background  

Parkinson's disease (PD) is the second most common neurodegenerative disorder. As there is no definitive diagnostic test, its diagnosis is based on clinical criteria. Recently transcranial duplex scanning (TCD) of the substantia nigra in the brainstem has been proposed as an instrument to diagnose PD. We and others have found that TCD scanning of substantia nigra duplex is a relatively accurate diagnostic instrument in patients with parkinsonian symptoms. However, all studies on TCD so far have involved well-defined, later-stage PD patients, which will obviously lead to an overestimate of the diagnostic accuracy of TCD.