A new family of repetitive nucleotide sequences is restricted to the genus Zea

We have isolated a new family of moderately repetitive nucleotide sequences (about 2500 copies per haploid genome) specific to the genus Zea and absent in other graminaceous species. These sequences are interspersed in the genome and they show the same genomic organization pattern and similar copy number in all the Zea species examined. These two facts, consistency in the copy number and the same organization pattern, would indicate on the one hand that these sequences were amplified before the divergence of Zea species, and on the other hand that maize and all the teosintes could be considered as the same evolutionary population. Independent clones corresponding to the repetitive sequences have been isolated and sequenced from a genomic library of the teosinte, Zea diploperennis. The repeats, flanked by HaeIII sites, are more than 70% G + C-rich, on average 253 bp long and show 78% similarity to each other. These repetitive sequences are in a highly methylated-C context and they present some features resembling those of coding sequences, such as high CpG and low TpA content, and similar codon usage to maize genes in one of the reading frames. Moreover, the repetitive probe hybridizes with RNA extracted from different tissues of maize and from teosinte, indicating that these repeats or similar ones are present in transcribed sequences.     

Glandular trichomes and essential oil constituents ofCalamintha menthifolia (Lamiaceae)

Plant material ofCalamintha menthifolia was collected from two populations grown in the Vikos-Aoos area (NW. Greece). The structure and ontogeny of the glandular trichomes and the chemical composition of the secreted essential oil were studied. The leaves ofC. menthifolia have numerous glandular trichomes of three morphological distinct types: 1) glandular scales with a unicellular foot and stalk, and a 12-celled head, 2) glandular hairs with a unicellular foot and stalk, and a unicellular pear-shaped head and 3) glandular hairs with a unicellular foot, a bicellular stalk and a unicellular elongated head. Qualitative and quantitative GC-MS analyses of the essential oils revealed piperitone oxide as the main constituent in both populations. In the light of these results the relationships beweenC. menthifolia and other members of theSatureja group as well as its taxonomy are discussed.     

Ca2+ regulation of thyroid NADPH-dependent H2O2 generation

A thyroid particulate fraction contains an NADPH-dependent H2O2-generating enzyme which requires Ca2+ for activity. A Chaps solubilized extract of the thyroid particulate fraction partially purified by DEAE chromatography did not show a dependence on Ca2+ for activity. Preincubation of the particulate fraction with Ca2+ yielded a preparation insensitive to Ca2+. The non-particulate fraction obtained after incubation of the particles in the presence of Ca2+ was able to inhibit, in the presence of EGTA, the Ca2+-desensitized particulate fraction and the enzyme isolated on DEAE. It is concluded that the reversible Ca2+ activation of the NADPH-dependent H2O2 generation was modulated in porcine thyroid tissue by (a) calcium-releasable inhibitor protein(s).     

Immunological properties of O2.- generating oxidase from bovine neutrophils

Two antisera have been prepared against the O2.- generating oxidase purified from bovine polymorphonuclear neutrophils (PMNs). The first antiserum was directed against the enzymatically active fraction obtained after isoelectric focusing (pI oxidase), which consisted of a major protein of Mr 65,000 [(1985) Biochemistry 24, 7231-7239]. The second antiserum was directed against the 65 kDa band excised from an SDS-polyacrylamide gel after electrophoresis of the pI oxidase preparation. The pI oxidase antiserum inhibited O2.- generation by PMN cells, PMN membranes and detergent-solubilized membranes. The 65 kDa band antiserum was virtually non-inhibitory against PMN cells; in contrast, it was nearly as potent as the pI oxidase antiserum on PMN membranes and detergent-solubilized membranes. Inhibition of O2.- generation by the pI oxidase antiserum was correlated with the immunoreactivity of four membrane-bound proteins of 65, 54, 18 and 16 kDa; the 65 kDa band antiserum reacted only with the two proteins of 65 and 54 kDa. It is concluded that the 18 and 16 kDa proteins, present in trace amounts in the pI oxidase preparation, are probably potent catalysts of the respiratory burst.     

Salivary hormones: a new aspect of oral physiology

Aside from the digestive enzymes the submandibular salivary glands (SSG) synthetize other polypeptides, detected also in saliva, with varied biological activity; NGF and EGF are the knowest. However, over the last decade, steroids hormones have been also found out in the saliva at the same concentrations that the free plasma fraction. The origin of these hormones is largely discussed and certain authors have even proposed a local synthesis for them. This matter, is of clinical interest because gingiva and buccal tissues are knowingly sensitive to steroids. Besides, woman ovulation appears to be monitored through progesterone fluctuations in saliva. Another kind of salivary substances is formed by the neuropeptides of the gut-brain axis, mainly VIP and SRIF. The former likely of nervous origin seems to be involved in the atropine-resistant salivary secretion, whereas the latter-likely of SSG origin--appears as a factor associated with glycemia control.     

Thyroid function and trisomy 21. TSH increase and rT3 deficiency

An excess of thyrotropin (TSH) with normal levels of tetraiodothyronine (T4) and of 3,5,3'-triiodothyronine (T3) was confirmed in the serum of 78 trisomy 21 children. A severe deficiency of 3,3',5'-triiodo-thyronine (rT3 or reverse T3) was observed and the decrease of the rT3/TSH ratio was highly significant. These new facts suggest that the rT3 deficiency plays a peculiar role in trisomy 21 (maybe through the regulation of one or few steps of monocarbons' metabolism). A systematic control of thyroid function (including the patient's rT3 level) is mandatory for the follow-up of every trisomy 21 patient.     

Periodic cleavage of poly(dA) by oligothymidylates covalently linked to the 1,10-phenanthroline-copper complex

1,10-Phenanthroline (OP) was covalently attached to the 3'-terminus of two oligothymidylates via different linkers [abbreviated as T8-(OP) and T6-(OP)]. In the presence of Cu2+ and 3-mercaptopropionic acid (MPA), these reagents induce a hybridization-dependent cleavage of poly(dA) and of a 27 nucleotide long oligodeoxynucleotide containing an A8 sequence. The principal cleavage sites on the 27-mer span four residues located near the 3'-terminal phosphate group of T8-(OP). When poly(dA) was degraded by T6-(OP) and T8-(OP), a series of bands were obtained corresponding to a repeat unit of six and eight nucleotides, respectively. This periodicity reflects the cooperative binding of oligothymidylate-OP to the polynucleotide matrix and the localized nicking sites.     

Comparison of the amino acid sequences of human protamines HP2 and HP3 and of intermediate basic nuclear proteins HPS1 and HPS2. Structural evidence that HPS1 and HPS2 are pro-protamines

Two intermediate nuclear basic proteins HPS1 and HPS2 were isolated from human sperm. They were characterized by their electrophoretic mobility in acid-urea gels, their amino acid composition, and their peptide maps after digestion by endoproteinase Lys-C and by endoproteinase Glu-C. Their amino-terminal amino acid sequences have also been determined. The structural data thus obtained suggest that HPS1 and HPS2 are precursors of human protamines HP2 and HP3.