Inheritance of a mutant histocompatibility gene and a new mammary tumor virus genome in the B6.KH-84 mouse strain

The potential association between integration or deletion of mouse mammary tumor virus (MMTV) retroviral sequences and the appearance of non-H-2 histocompatibility (H) antigen mutations was investigated. Genomic blots from inbred strains carrying 22 loss, gain-loss, and gain mutations on the BALB/c and C57BL/6 backgrounds were hybridized with probes homologous to the long terminal repeat (LTR) and envelope (env) regions of MMTV. Twenty-one mutants were identical in restriction patterns to the respective background strains with all tested restriction enzymes and both probes. However, genomic blots of one gain mutant, B6.C-KH-84, exhibited restriction fragments which were not exhibited by either of the parental strains, C57BL/6 or BALB/c. An additional 5.5 kb Eco RI fragment was observed with the env probe and additional 9.2 kb and 5.5 kb fragments were observed with the LTR probe. These observations were substantiated by hybridization of these two probes with genomic blots generated with additional restriction enzymes. Assuming that the new provirus contains a single, internal Eco RI site as has been observed for other MMTV proviral sequences, it is presumed that the new provirus includes both 5 and 3 LTRs in addition to the env region. Based on the unique sizes of the observed restriction fragments relative to other identified MMTV proviral sequences, this provirus has been designated Mtv-22. The potential role of Mtv-22 in the genesis of the gained histocompatibility antigen in B6.C-KH-84 is discussed.On leave of absence from Istituto Nazionale per to Studio e la Cura dei Tumori, Milano, Italy     

Gonadal steroid modulation of brain opioid systems

It is becoming increasingly clear that the effects of the opioids and their synthetic analogs on anterior pituitary function largely depend on the steroid milieu present in the animal at time of drug administration. However, it is still unclear whether gonadal steroids regulate the opioid-modulated mechanisms by affecting the number of opiate receptors in the brain. To further investigate these issues, the effects of opiate agonists and antagonists on LH, FSH and prolactin (Prl) secretion have been studied in: (a) normal and castrated male rats, and (b) normally cycling female rats. The binding characteristics of the brain subclass of mu opiate receptors have been analyzed in the same group of experimental animals; this type of receptors seems to be particularly involved in the control of gonadotropin and Prl release. When injected intraventricularly into normal male rats, morphine (200 micrograms/rat) induced in a significant elevation of serum LH levels at 10 and 20 min. In long-term castrated animals the administration of the drug significantly reduced LH secretion at 40 and 60 min after the injection, the inhibition lasted up to 180 min. Morphine, when given intraventricularly to normal males, induced a conspicuous and significant elevation of serum Prl levels at 10, 20, 40 and 60 min after treatment. However, when the drug was administered to castrated rats, it did not significantly affect Prl release at any time interval considered. Morphine intraventricular injections did not modify serum FSH levels either in normal or in castrated male rats. The concentration of mu opiate receptors was found to be similar when measured in the whole brain of normal and orchidectomized rats. In adult cycling female rats, s.c. injections of naloxone (2.5 mg/kg) stimulated LH release in every phase of the estrous cycle; the magnitude of the responses was highly variable, being particularly elevated at 16.00 h of the day of proestrous and at 10.00, 12.00 and 14.00 h of the day of estrous. Conversely, LH response to naloxone was totally obliterated at 18.00 and 20.00 h of the day of proestrous, when the preovulatory LH surge was found to occur. The concentration of brain opiate receptors of the mu type showed significant variations during the different phases of the estrous cycle, with higher levels at 12.00 h of the day of proestrous and at 18.00 h of the day of estrous.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cloning of histidine genes of Azospirillum brasilense: organization of the ABFH gene cluster and nucleotide sequence of the hisB gene

Summary A cluster of four Azospirillum brasilense histidine biosynthetic genes, hisA, hisB, hisF and hisH, was identified on a 4.5 kb DNA fragment and its organization studied by complementation analysis of Escherichia coli mutations and nucleotide sequence. The nucleotide sequence of a 1.3 kb fragment that complemented the E. coli hisB mutation was determined and an ORF of 624 nucleotides which can code for a protein of 207 amino acids was identified. A significant base sequence homology with the carboxyterminal moiety of the E. coli hisB gene (0.53) and the Saccharomyces cerevisiae HIS3 gene (0.44), coding for an imidazole glycerolphosphate dehydratase activity was found. The amino acid sequence and composition, the hydropathic profile and the predicted secondary structures of the yeast, E. coli and A. brasilense proteins were compared. The significance of the data presented is discussed.Abbreviations IGP imidazole glycerolphosphate - HP histidinolphosphate     

Tachykinins protect against ethanol-induced gastric lesions in rats

Subcutaneous pretreatment of rats with neurokinin (NK) A or the fragment NKA(4-10) reduced the degree of gastric lesions induced by oral administration of 96% ethanol. The protective effect of NKA(4-10) was dose-dependent. Arg-NKB, the water soluble derivative of NKB, was less effective than NKA or NKA(4-10) while [Me-Phe7]NKB, substance P (SP) and SP-methyl-ester were inactive. The NKA(4-10) antilesion effect was reversed by pretreatment with N-ethyl-maleimide, suggesting a possible involvement of sulphydryls in its action. Among the nonmammalian tachykinins, kassinin significantly reduced ethanol-induced lesions while eledoisin and physalaemin at equivalent molar doses were inactive. These results provide, for the first time, evidence that tachykinins and their derivatives exert gastroprotective activity toward ethanol-induced haemorrhagic lesions. Assuming a receptor-mediated mechanism, NK-2 sites could be involved.     

An in vitro demonstration of peroxisome proliferation and increase in peroxisomal β-oxidation system mRNAs in cultured rat hepatocytes treated with ciprofibrate

Using the normal adult rat hepatocytes, plated on rat tail collagen-coated dishes and fed a chemically defined medium, we demonstrate here that ciprofibrate at 0.1 mM concentration, increases significantly the mRNA levels of fatty acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein, and thiolase (the three enzymes of the β-oxidation system), and causes peroxisome proliferation. Increase in mRNA levels of these genes was evident within 1 h and was maximal 24 h after the addition of ciprofibrate. In hepatocytes cultured in the absence of ciprofibrate, the basal levels of these enzymes were low and further declined with time. Concomitant treatment of hepatocytes with cycloheximide did not inhibit or superinduce the mRNA levels, indicating that this induction may represent a primary (direct) effect of this compound on the expression of these genes and does not apparently involve short-lived repressor protein(s).     

Expression of HOX homeogenes in human neuroblastoma cell culture lines

Mammalian genes containing a class-I homeobox (HOX genes) are highly expressed in the embryonic nervous system. As a first step towards the molecular analysis of the role these genes play in neural cells, we studied the expression of four human HOX genes in five neuroblastoma (NB) cell lines - SK-N-BE, CHP-134, IMR-32, SK-N-SH and LAN-1 - during the process of differentiation induced by treatment with retinoic acid (RA). The four genes, HOX1D, 2F, 3E and 4B, located at corresponding positions in the four HOX loci, share a high degree of sequence similarity with the Drosophila Deformed homeotic gene and constitute a homology group, group 10. One of these genes, HOX1D, is not expressed in the cells used, whereas the other three are highly expressed in untreated and RA-induced NB cells, even though the expression pattern in the various lines is slightly different for the three genes. Our analysis reveals a complex and specific expression pattern in these lines, paving the way to an identification of different NB-cell populations by means of specific HOX gene expression schemes. On the other hand, in every line studied, morphological maturation toward a neuronal differentiated phenotype appears to be associated with increased HOX gene expression.     

Extracellular matrix influences hormone and protein production by human chorionic villi

Summary Increasing evidence confirms that the extracellular matrix greatly influences cell behaviour and function. Collagen and fibrin are in contact with trophoblast throughout pregnancy. To investigate whether these two matrices influence hormon production by the trophoblast, explants from first-trimester chorionic villi were cultured for up to 30 days either a) in medium with agitation, b) embedded in type-I collagen (three-dimensional gels), or c) embedded in fibrin (three-dimensional gels). The supernatant culture medium was changed every 48 h and tested by radioimmunoassay for hCG, progesterone and pregnancy-associated plasma protein A. In addition, after 3, 7, 15, and 30 days of culture villi were fixed and studied by light and electron microscopy. Embedding in the extracellular matrix showed higher and longer-lasting production rates of all measured products and superior structural preservation as compared to cultures with agitation. Collagen matrix proved to be superior to fibrin. As established by several tests, this difference was neither due to thrombin used to polymerize fibrinogen, nor to differences in the diffusion rates through the two different matrices used. We conclude that extracellular matrix, particularly collagen, influences the synthesis of trophoblastic products. Embedding of the villous explants in three-dimensional gels constitutes a new method for long-term cultures of chorionic villi.This study was presented at the workshop Placental-and decidual-specific protein synthesis and secretion: regulation, role and interaction, Zemun, Belgrade, Yugoslavia, 19–20 May, 1988 (Bischof and Castellucci 1988; see also J. Aplin 1989), and at the 11th Rochester Trophoblast Conference, Rochester, N.Y. USA, 9–12 October 1988 (Castellucci et al. 1988)     

Hydrolysis and protection from hydrolysis of enkephalins in human plasma

Seven groups of enkephalin-degrading enzymes and three groups of inhibitors active on these enzymes were separated from human plasma. The activity of the enzymes in hydrolyzing enkephalins and of the inhibitors in protecting enkephalins from proteolysis was measured. Results obtained with the endogenous inhibitors were compared to those relative to synthetic inhibitors. Data obtained indicate that all enkephalin-degrading enzymes found in plasma are significantly inhibited by the endogenous substances present in this tissue. The inhibition of the different classes of plasma enzymes by two of the three groups of endogenous substances is quite uniform, while one group of inhibitors appears specific to dipeptidylpeptidases. Results obtained are discussed in terms of the functional role of the inhibitory substances and of the possible pharmacological implication of their presence in human plasma.     

Structure and function of hemoglobin in antarctic fishes and evolutionary implications

Summary The hematological features of cold-adapted, red-blooded Antarctic teleosts has prompted this study on the relationship between hemoglobin molecular structure and oxygen-binding properties. The hemolysates from 21 species of 5 families contained one component (Hb 1), often accompanied by an additional, minor one (Hb 2, 5%–10% of total). On the other hand, 3 species of Zoarcidae, a non-endemic family, had 4–5 components. All purified hemoglobins from the former group, but only 1–2 of the 4–5 hemoglobins of Zoarcidae, showed a strong Root effect (pH regulation of oxygen binding). Globins from each hemoglobin have been purified and characterised with respect to molecular structure in several species. The similarity between the complete amino acid sequence of one -chain and those of non-Antarctic -chains is lower than that among the latter sequences, suggesting independent pathways of evolution.Presented at the 5th SCAR Symposium on Antarctic Biology, Hobart, Australia (August 29th-September 3rd, 1988)