Heterogeneity of neural crest-derived melanocytes

The majority of melanocytes originate from the neural crest cells (NCC) that migrate, spread on the whole embryo’s body to form elements of the nervous system and skeleton, endocrinal glands, muscles and melanocytes. Human melanocytes differentiate mainly from the cranial and trunk NCC. Although melanocyte development has traditionally been associated with the dorsally migrating trunk NCC, there is evidence that a part of melanocytes arise from cells migrating ventrally. The ventral NCC differentiate into neurons and glia of the ganglia or Schwann cells. It has been suggested that the precursors for Schwann cells differentiate into melanocytes. As melanoblasts travel through the dermis, they multiply, follow the process of differentiation and invade the forming human fetal epidermis up to third month. After birth, melanocytes lose the ability to proliferate, except the hair melanocytes that renew during the hair cycle. The localization of neural crest-derived melanocytes in non-cutaneous places e.g. eye (the choroid and stroma of the iris and the ciliary body), ear (cells of the vestibular organ, cochlear stria vascularis), meninges of the brain, heart seems to indicate that repertoire of melanocyte functions is much wider than we expected e.g. the protection of tissues from potentially harmful factors (e.g. free radicals, binding toxins), storage ions, and anti-inflammatory action.     

Analysis of 5-methylcytosine in DNA of breast and colon cancer tissues

5-methylcytosine (m(5)C) can be used as a sensitive marker of progress of the tumor formation induced by the oxidative damage reactions. We have analyzed the amount of m(5)C in DNA of patients with breast and colon cancers. Two dimensional thin layer chromatography (TLC) has been used to monitor 5-methylcytosine level in DNA extracted from cancer tissues. The level of methylation of cytosine at C-5 position in DNA from breast cancer patients correlates well with the malignancy of tumors. Interestingly higher amount of m(5)C in DNA for the breast cancer patients treated with different chemotherapeutics was observed. It suggests an activation of DNA methyltransferase as well as a genomic suppression of the DNA repair genes expression. These differences clearly reflect the health condition of patients and support the global analysis of m(5)C in DNA as a good marker for diagnosis of neoplasia in clinical practice.     

Cannabinoid Receptor 1 Signaling in Embryo Neurodevelopment

In utero exposure to tetrahydrocannabinol, the psychoactive component of marijuana, is associated with an increased risk for neurodevelopmental defects in the offspring by interfering with the functioning of the endocannabinoid (eCB) system. At the present time, it is not clearly known whether the eCB system is present before neurogenesis. Using an array of biochemical techniques, we analyzed the levels of CB1 receptors, eCBs (AEA and 2‐AG), and the enzymes (NAPE‐PLD, DAGLα, DAGLβ, MAGL, and FAAH) involved in the metabolism of the eCBs in chick and mouse models during development. The findings demonstrate the presence of eCB system in early embryo before neurogenesis. The eCB system might play a critical role in early embryogenesis and there might be adverse developmental consequences of in utero exposure to marijuana and other drugs of abuse during this period.     

Construction and preliminary characterisation of mini-derivatives of a large (107-kb) cryptic plasmid of the sulfur bacterium Thiobacillus versutus

Abstract Several mini-replicons, derivatives of a large (107-kb) cryptic Thiobacillus versutus pTAV1 plasmid, were obtained. The pTAV1 derivatives confer all functions sufficient for autonomous replication in T. versutus but they cannot be maintained in Escherichia coli . The fragment of pTAV1 (4-kb) included in the smallest mini-replicon, pTAV202, encodes for two proteins of approximately 26 and 45 kDa. The region responsible for stable maintenance of pTAV1 derivatives (and presumably entire pTAV1) was located in defined 14-kb fragment of pTAV1 genome. Hybrid plasmids composed of E. coli vectors (pBGS18 or pWSK29) and pTAV202 replicon were constructed and their activity in both hosts tested.     

Differentially expressed genes in embryonic cardiac tissues of mice lacking <Emphasis Type="Italic">Folr1</Emphasis>gene activity

Background  

Heart anomalies are the most frequently observed among all human congenital defects. As with the situation for neural tube defects (NTDs), it has been demonstrated that women who use multivitamins containing folic acid peri-conceptionally have a reduced risk for delivering offspring with conotruncal heart defects [1–3]. Cellular folate transport is mediated by a receptor or binding protein and by an anionic transporter protein system. Defective function of the Folr1 (also known as Folbp1; homologue of human FRα) gene in mice results in inadequate transport, accumulation, or metabolism of folate during cardiovascular morphogenesis.     

Design and Comparative Evaluation of the Anticonvulsant Profile,Carbonic-Anhydrate Inhibition and Teratogenicity of Novel Carbamate Derivatives of Branched Aliphatic Carboxylic Acids with 4-Aminobenzensulfonamide

Epilepsy is one of the most common neurological diseases, with between 34 and 76 per 100,000 people developing epilepsy annually. Epilepsy therapy for the past 100⁺ years is based on the use of antiepileptic drugs (AEDs). Despite the availability of more than twenty old and new AEDs, approximately 30% of patients with epilepsy are not seizure-free with the existing medications. In addition, the clinical use of the existing AEDs is restricted by their side-effects, including the teratogenicity associated with valproic acid that restricts its use in women of child-bearing age. Thus, there is an unmet clinical need to develop new, effective AEDs. In the present study, a novel class of carbamates incorporating phenethyl or branched aliphatic chains with 6–9 carbons in their side-chain, and 4-benzenesulfonamide-carbamate moieties were synthesized and evaluated for their anticonvulsant activity, teratogenicity and carbonic anhydrase (CA) inhibition. Three of the ten newly synthesized carbamates showed anticonvulsant activity in the maximal-electroshock (MES) and 6 Hz tests in rodents. In mice, 3-methyl-2-propylpentyl(4-sulfamoylphenyl)carbamate(1), 3-methyl-pentan-2-yl-(4-sulfamoylphenyl)carbamate (9) and 3-methylpentyl, (4-sulfamoylphenyl)carbamate (10) had ED₅₀ values of 136, 31 and 14 mg/kg (MES) and 74, 53, and 80 mg/kg (6 Hz), respectively. Compound (10) had rat-MES-ED₅₀?=?13 mg/kg and ED₅₀ of 59 mg/kg at the mouse-corneal-kindling test. These potent carbamates (1,9,10) induced neural tube defects only at doses markedly exceeding their anticonvuslnat-ED₅₀ values. None of these compounds were potent inhibitors of CA IV, but inhibited CA isoforms I, II and VII. The anticonvulsant properties of these compounds and particularly compound 10 make them potential candidates for further evaluation and development as new AEDs.     

Association of R6K plasmid replicative intermediates with the folded chromosome of Escherichiacoli

When $\text{Escherichia}\text{coli}$ strain CSH50(R6K) is lysed so as to preserve the folded chromosome structure approximately 9 of the 11 R6K molecules maintained per chromosomal equivalent cosediment with the host nucleoid on a neutral sucrose gradient; the remaining 2 plasmids sediment at their normal rate. When cells are briefly labeled with [³H]thymidine, the majority of plasmid replicative intermediates and nascent mature plasmids are found in the plasmid subpopulation that cosediments with host folded chromosomes. This finding suggests that plasmid replication occurs in a restricted cellular locus, perhaps even while in association with its host's folded chromosome.     

Sampling issues in quantitative analysis of dendritic spines morphology

ABSTRACT: BACKGROUND: Quantitative analysis of changes in dendritic spine morphology has become an interesting issue in contemporary neuroscience. However, the diversity in dendritic spines population might seriously influence the results of measurements in which their morphology is studied, the detection of differences in spine morphology between control and test group is often compromised by the number of dendritic spines taken for analysis. In order to estimate how severe is such an impact we have performed Monte Carlo simulations examining various experimental setups and statistical approaches. The confocal images of dendritic spines from hippocampal dissociated cultures have been used to create a set of variables exploited as the simulation resources. RESULTS: The tabulated results of simulations are given, providing the number of dendritic spines required for the detection of hidden morphological differences between control and test group, in spine head-width, length and area. It turns out that this is the head-width among these three variables, where the changes are most easily detected. Simulation of changes occurring in a subpopulation of spines reveal the strong dependence of detectability on the statistical approach applied. The analysis based on comparison of percentage of spines in subclasses is less sensitive than the direct comparison of relevant variables describing spines morphology. CONCLUSIONS: We evaluated the sampling aspect and effect of systematic morphological variation on detecting the differences in spine morphology. Provided results may serve as a guideline in selecting the number of samples to be studied in a planned experiment. Our simulations might be a step towards the development of a standardized method of quantitative comparison of dendritic spines morphology, in which different sources of errors are considered.     

Independence with respect to Ca2+ changes of the neutrophil respiratory and secretory response to exogenous phospholipase C and possible involvement of diacylglycerol and protein kinase C

Exogenous phospholipase C induces in human neutrophils the activation of a respiratory burst, measured as O₂ consumption and O₂^? production and of secretion of specific granules, measured as release of vitamin B-12 binding protein. The secretory response is minimal and follows the onset of the respiratory response. Studies carried out using cells prelabeled with |³H|glycerol and³²P on the molecular mechanism of the stimulations demonstrate that the effects are dependent on the formation of diacylglycerol by hydrolysis of different classes of glycerophospholipids. They are, however, independent of the activation of a ‘phosphoinositide turnover’ as occurs in cells stimulated with fMet-Leu-Phe. Furthermore, the respiratory and secretory responses to exogenous phospholipase C are not associated with moditications of cytosolic Ca²⁺ concentration measured with the Quin-2 method, and the release of bound Ca²⁺, measured with the membrane probe, chlorotetracycline. Apart from a quantitative difference, mostly regarding the ratio of the intensity of the respiratory and secretory responses, the effects caused by exogenous phospholipase C are qualitative;y similar to those induced by phorbol myristate acetate and are probably linked to an involvement of protein kinase C, activated by diacylglycerol liberated in the plasma membrane.