Morphogenetic and cellular movements that shape the mouse cerebellum; insights from genetic fate mapping

We used the cerebellum as a model to study the morphogenetic and cellular processes underlying the formation of elaborate brain structures from a simple neural tube, using an inducible genetic fate mapping approach in mouse. We demonstrate how a 90 degrees rotation between embryonic days 9 and 12 converts the rostral-caudal axis of dorsal rhombomere 1 into the medial-lateral axis of the wing-like bilateral cerebellar primordium. With the appropriate use of promoters, we marked specific medial-lateral domains of the cerebellar primordium and derived a positional fate map of the murine cerebellum. We show that the adult medial cerebellum is produced by expansion, rather than fusion, of the thin medial primordium. Furthermore, ventricular-derived cells maintain their original medial-lateral coordinates into the adult, whereas rhombic lip-derived granule cells undergo lateral to medial posterior transverse migrations during foliation. Thus, we show that progressive changes in the axes of the cerebellum underlie its genesis.     

Chromosome numbers of some species of the genus<Emphasis Type="Italic">Hieracium</Emphasis> s.str. (<Emphasis Type="Italic">Asteraceae</Emphasis>) from Turkey

Results of a karyological analysis of eight species collected from northeast Anatolia, Turkey are presented. The following chromosome numbers were determined:H. medianiforme (Litv. etZahn)Juxip 2n=36,H. karagollense (Zahn)P.D. Sell etC. West 2n=36,H. argillaceoides (Litv. etZahn)Juxip 2n=36,H. amblylepis Boiss. 2n=27,H. lanceolatum Vill. 2n=27,H. asterodermum (Woronow etZahn)Juxip 2n=27,H. umbellatum L. 2n=18,H. laevigatum Willd. 2n=27. The chromosome numbers of five of these seven species are presented for the first time. The results show a high proportion of triploids and tetraploids within the taxa studied.     

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35–65% cobalt, 20–30% chromium, 0–30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (±S.D.) CB-MN frequencies (‰) in peripheral lymphocytes were 4.00 (±2.98) among the dental technicians and 1.40 (±1.30) among the controls, a statistically significant difference (P<0.005). The mean (±S.D.) MN frequencies (‰) in nasal cells were 3.50 (±1.80) among the dental technicians and 1.19 (±0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.     

Trace Elements and Heavy Metals in Hair of Stage III Breast Cancer Patients

This prospective study was designed to compare the hair levels of 36 elements in 52 patients with stage III breast cancer to those of an equal number of healthy individuals. Principal component and cluster analysis were used for source of identification and apportionment of heavy metals and trace elements in these two groups. A higher average level of iron was found in samples from patients while controls had higher levels of calcium. Both patients and controls had elevated levels of tin, magnesium, zinc, and sodium. Almost all element values in cancer patients showed higher dispersion and asymmetry than in healthy controls. Between the two groups, there were statistically significant differences in the concentrations of silver, arsenic, gold, boron, barium, beryllium, calcium, cadmium, cerium, cobalt, cesium, gadolinium, manganese, nickel, lead, antimony, scandium, selenium, and zinc (p?相似文献   

Distribution of matrix metalloproteinases MMP-1, MMP-2, MMP-8 and tissue inhibitor of matrix metalloproteinases-2 in nasal polyposis and chronic rhinosinusitis

Nasal polyposis (NP), a chronic inflammatory disease of the upper airway, is a subgroup of chronic rhinosinusitis (CRS). Matrix metallo-proteinases (MMPs) and their tissue inhibitors (TIMPs) are considered to play important roles in the pathogenesis of nasal polyposis. The aim of the current study was to evaluate and compare the levels of MMP-1, MMP-2, MMP-8 and TIMP-2 in NP and CRS with normal nasal mucosa by using immunohistochemistry. Twenty-five patients with NP and fifteen patients with CRS underwent endoscopic sinus surgery. Diseased mucosal samples were obtained from ethmoidal sinuses. Control nasal mucosa (n=10) was obtained from inferior nasal turbinate. Immunohistochemistry for MMP-1, MMP-2, MMP-8 and TIMP-2 was performed. The expression of MMP-1, MMP-2 and MMP-8 significantly increased in NP and CRS compared with control (p<0.05). The distribution of TIMP-2 was higher in CRS than control and NP respectively (p<0.05). MMP-1 immunoreactivity was distributed in the extracellular matrix whereas MMP-2, MMP-8 and TIMP-2 immunostaining was present in the epithelium, submucosal glands, vascular endothelium and inflammatory cells in CRS and NP. We suggest that differences in histological features between CRS and NP might be related to the expression of MMP-1, MMP-2, MMP-8 and their tissue inhibitor-2.     

Phosphinothricin-tripeptide biosynthesis: An original version of bacterial secondary metabolism?

Streptomyces viridochromogenes Tü494 produces the herbicide phosphinothricyl-alanyl-alanine (phosphinothricin-tripeptide = PTT; bialaphos). Its bioactive moiety phosphinothricin competitively inhibits bacterial and plant glutamine synthetases. The biosynthesis of PTT includes the synthesis of the unusual amino acid N-acetyl-demethyl-phosphinothricin and a three step condensation via non-ribosomal peptide synthetases. Two characteristics within the PTT biosynthesis make it suitable to study the evolution of secondary metabolism biosynthesis. First, PTT biosynthesis represents the only known system where all peptide synthetase modules are located on separate proteins. This ‘single enzyme system’ might be an archetype of the multimodular and multienzymatic non-ribosomal peptide synthetases in evolutionary terms. The second interesting feature of PTT biosynthesis is the pathway-specific aconitase Pmi that is involved in the supply of N-acetyl-demethyl-phosphinothricin. Pmi is highly similar to the tricarboxylic acid aconitase AcnA. They share 64% identity at the DNA level and both belong to the Iron-Regulatory-Protein/AcnA family. Despite their high sequence similarity, AcnA and Pmi catalyze different reactions and are not able to substitute for each other. Thus, the enzyme pair AcnA/Pmi presents an example of the evolution of a secondary metabolite-specific enzyme from a primary metabolism enzyme.     

Investigation of some yield and fibre quality characteristics of interspecific hybrid (Gossypium hirsutum L. x G. barbadense L.) cotton varieties

Interspecific hybrid cottons (Gossypium hirsutum L. x G. barbadense L.) have great both yield and quality potential. This study was conducted to determine potential yields and quality characteristics of hybrid cotton varieties in southeastern Anatolia region of Turkey. The experiment was set out a completely randomized block design with four replications during 2003 and 2004 at University of Dicle, Faculty of Agriculture Experimental Field. Seven interspecific hybrid cotton varieties (48-08, Sevilla, Europe, Ica, Etna, 14-08 and Acalpi) which were obtained from Israel, and commonly grown varieties in this region, non-hybrid cotton varieties, GW Teks and DP-Opal were used as the materials of the study. Difference among the cultivars was significant for all traits except sympodial branch. Maximum number of boll and lint yield was 20.18 n plant(-1) and 1685.8 kg ha(-1) from interspecific hybrid cotton Ica, while interspecific hybrid cotton Europe recorded the lowest number of boll and lint yield. Interspecific hybrid cotton varieties showed higher value for fibre length, fibre fineness and fibre strength than non-hybrid cotton varieties. The longest fibres were obtained from Acalpi and Etna (34.08 and 33.88 mm), while non-hybrid varieties, DP-Opal and GW-Teks, had the lowest fibre length, 28.50 and 30.03 mm, respectively. The finest fibres obtained from Ica and 48-08 (3.42 and 3.45 mic.), the strongest fibres from Etna and Acalpi (40.07 and 40.23 g tex(-1)), and most elongation fibres from Acalpi (8.00%) and Sevilla (7.45%). Lint yield correlated positive and significant with fiber length.