The "2 + 1" mechanism as the basis for synergism in the neutron-photon irradiation of the spermatozoal genome in Drosophila melanogaster

Cytogenetic analysis of polytene chromosomes of Drosophila melanogaster locus-specific mutants induced by consecutive neutron-photon irradiation has shown that their genome contains multiple intra- and inter-chromosome exchanges, including triradials, evidencing the synergistic action of such combined exposure. The appearance of the triradials may be only possible on the base of an interaction between a double and a single DNA strand breaks. The important significance of such interaction as the general mechanism for production of chromosome aberrations in irradiated cells of higher eucaryotes had been postulated by N. V. Luchnik as early as 10 years ago, but only nowadays it has been confirmed experimentally.     

HPLC detection of serotonin within the rat cochlea

This study was performed to analyse the cochlear concentrations of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA), their sources and modifications induced by noise exposure. Superior cervical ganglionectomy did not modify these concentrations. However, removal of the blood by aortic perfusion reduced significantly (about 76%) the cochlear concentration of 5-HT without affecting the 5-HIAA concentration. These results indicate that blood constitutes an important source of 5-HT to the cochlea, opposite to the superior cervical ganglion. Exposure to noise at 90 dB SPL did not modify the total cochlear concentrations of 5-HT and 5-HIAA, or the concentrations remaining after removal of the blood, suggesting that 5-HT could have a modulatory role in the cochlea distinct from that of olivocochlear neurotransmitters.     

Polymorphism of noncoding regions of the mitochondrial genome in the indigenous population of Southeastern Tuva Republic

Deletion-insertion polymorphism of the V region and restriction polymorphism of D-loop for seven restriction enzymes--AspS9I (Cfr3I isoschizomere), BamHI, Bme18I (AvaII), EcoRV, HaeIII, KpnI, and Kzo9I (Sau3AI)--in mitochondrial DNA (mt DNA) were studied in the indigenous population of southeastern Tuva Republic. The results were compared with the data on Russians, Mongols, Buryats, and Altaians. Tuvinians significantly differed from Mongols in the frequency of the 9-bp deletion of the V region (1.89 and 8.07%, respectively). Additionally, significant differences between Tuvinians and samples of Mongols and Russians were obtained for frequencies of the AspS9I, HaeIII, and KpnI restriction sites. A comparison of the polymorphism of mitochondrial genome in individuals of different sexes and ages was performed in the studied sample.     

Delayed effects of organochlorine pesticides in man

Available information on organochlorines and the chronic effects of exposure to them are set out. Organochlorinated compounds are the most persistent pesticides and can be found in all ecosystems. Although they are generally efficient in pest control, they are also a potent environment pollutant and can provoke health problems in man. The evidences of the carcinogenic potential of organochlorines are controversial and insufficient, but they have been related to an increase in the incidence of some kinds of tumors, such as leukemia and solid tumors. Reproductive effects, due to anti-androgenic and estrogenic action, on embryonic virilization, the incidence of abortion and the frequency of prematurity, have also been observed. The accumulation of the organochlorines in the adipous tissue is positively correlated to the increase in aging and could be implicated in the development of aging diseases, such as Parkinson's disease. The effects of pesticides on human health have not yet been completely elucidated. Genotoxicity is one of the most serious of the possible harmful effects caused by these compounds and calls for special attention in view of the irreversible nature of the process and to the long latency associated with its manifestation.     

Carrier screening for cystic fibrosis: costs and clinical outcomes

Generally, interferon-gamma (IFN-gamma) is considered a critical regulator of T cell mediated inflammation. For this reason, we investigated the pathogenesis of lymphocytic choriomeningitis in mice with a targeted defect of the gene encoding this cytokine. Our results revealed that IFN-gamma is redundant in the afferent phase of the antiviral T cell response as well as a local mediator of this T cell mediated inflammatory disease. However, IFN-gamma may play an indirect role as it is involved in reducing extraneural infection that may compete with CNS for available effector cells. Analysis of the inflammatory exudate disclosed that leucocyte recruitment was unimpaired in the absence of IFN-gamma as was the upregulation of ICAM-1 and VCAM-1 on endothelium at the inflammatory site. However, local macrophage activation (production of tumor necrosis-alpha and NO) was significantly impaired. Notably, a viral peptide could also elicit a T cell mediated inflammatory response in virus-primed IFN-gamma knock-out mice, indicating that redundancy of this cytokine as a proinflammatory mediator is not restricted to inflammatory reactions triggered by an active infection. Thus, T cell mediated inflammation may be induced in the absence of IFN-gamma and local macrophage activation.     

The delayed entry of thoracic neural crest cells into the dorsolateral path is a consequence of the late emigration of melanogenic neural crest cells from the neural tube

Recent studies have shown that changes in dendritic architecture are an important component of functional plasticity in the adult central nervous system. In the present study, we determined whether gonadectomy induces changes in dendritic architecture in the arcuate nucleus, a target tissue for gonadal hormones. A combination of retrograde labeling with systemically injected Fluoro-Gold and intracellular injection of neurons in a fixed-slice preparation was used to examine the morphology of neuroendocrine neurons in the rat arcuate nucleus. Intracellullary filled arcuate neuroendocrine neurons (8-21 neurons per brain) from intact (n = 5) and orchidectomized (n = 5) animals were reconstructed with the aid of a computer microscope. A quantitative analysis revealed that orchidectomy had no effect on the number and distribution of Fluoro-Gold-labeled neuroendocrine neurons in the rat arcuate nucleus. The morphology of arcuate neuroendocrine neurons in intact animals was relatively simple, with the majority of neurons (79%) having only two primary dendrites and few dendritic spines. Compared with intact controls, arcuate neuroendocrine neurons in the orchidectomized group had significantly larger somatic profile areas and exhibited significant increases in dendrite length, dendrite volume, terminal branch number, and spines per unit length of dendrite. The increase in terminal branch number in orchidectomized animals was due primarily to the appearance of short branches that gave a striking, claw-like appearance to many of the distal dendrites. These results provide evidence for hormonal regulation of dendritic morphology of arcuate neuroendocrine neurons in adult mammals.     

Release and analysis of polypeptides and glycopolypeptides from formalin-fixed, paraffin wax-embedded tissue

Archival tissue specimens are commonly stored as formalin-fixed, paraffin wax-embedded blocks. Formalin fixation facilitates excellent morphological preservation, and the immunoreactivity of many antigens is preserved, but formalin-induced chemical cross-linking of proteins renders them insoluble and inaccessible to standard biochemical extraction and analytical methods. Thus, biochemical analysis of tissue components identified by histochemistry, with the advantage of long-term clinical follow-up, is precluded. We have applied cyanogen bromide cleavage, a technique used routinely for fragmenting proteins for sequencing experiments, to solubilize transferrin polypeptides and glycopolypeptides from formalin-fixed, paraffin wax-embedded rat liver. Cyanogen bromide cleaves protein specifically at methionine residues, yielding a predictable array of polypeptide fragments. Subsequent oligosaccharide analysis of the transferrin glycopolypeptides by anion exchange chromatography confirmed that, in addition to successful release of polypeptide chains, sialylated oligosaccharide structures remained intact after cyanogen bromide cleavage. This approach may have wide applicability to a range of research interests in which correlation of tissue biochemistry with long-term follow-up is advantageous.