The beta chorionic gonadotropin-beta luteinizing gene cluster maps to human chromosome 19

Summary We used a cloned human cDNA probe homologous to the placenta chorionic gonadotropin subunit (CGB) and to the pituitary luteinizing hormone subunit (LHB) and Southern blotting techniques to analyse DNA from a series of rodent x human somatic cell hybrids for the presence of specific gonadotropin subunit related sequences. Our results provide evidence for the assignment and linkage of the eight genes (or pseudogenes) coding for the subunit of these glycoprotein hormones to chromosome 19. Moreover, we observed a strict concordance between the permissivity of mouse x man hybrid cells to enteroviruses (which is linked to the presence of specific cell receptors encoded by human chromosome 19) and the presence of CGB and LHB related sequences, thus confirming the localization of the structural genes for the subunits on chromosome 19.This work was supported in part by INSERM grants CRL 81 1041 and by MRC grant MT 4860     

Some characteristics of mitochondrial multienzyme systems from rat liver mitochondria after heating of rats]

A character of rat liver mitochondria degradation after the heat treatment of animals is studied. It is found that mitochondria under the effect of elevated temperature do not considerably change their functional characteristics and thus they are capable to provide the normal rate of ATP synthesis, the rate of succinate oxidation being slightly increased. At the same time the heating caused the degradation of mitochondria which results in the decrease of their thermostability, in the increased susceptibility to lytic effect of trypsin and phospholipase D, and in the activation of succinate dehydrogenase and cytochrome c oxidase. The mitochondria degradation is due to the formation of "latent impairments" in the structure of mitochondria.     

The effect of perinatal oestrogen treatment on the troph-hormone secreting cells of the anterior pituitary of the rat

Late effect of the perinatal administration of oestradiol dipropionate on pituitary gonadotrophs and the morphology of the LH-RH neuronal system was tested both in male and female rats. Oestrogen caused a severe reduction in the number and size of immunodetectable gonadotrophs in both sexes. By the 90th day of life, however, immunomorphology and distribution of the gonadotroph cells had became normal, and also the LH-RH system of the animals was similar to that of the intact controls. The lack of vaginal cycles indicated, however, that oestrogen might have permanently impaired higher brain centers regulating cyclic gonadotroph hormone release.     

The importance of FeEDTA for reversibility of phosphate-induced chlorosis in maize (Zea mays L.)

Chlorosis induced with a supraoptimum dose of phosphorus in nutrient solution (69 mg P l^-1) was reverted by spraying of leaves of chlorotio maize plants (Zea mays L.) with FeEDTA. Biomass formation, chlorophyll and iron content were decreased in the above-ground parts of plants grown under chlorosis-inducing conditions. Spraying always decreased content of inorganic phosphorus (P_i/Fe ratio was significantly changed), increased chlorophyll content in old plants and stimulated dry mass formation at supraoptimum phosphorus doses. FeEDTA application improved phosphate utilization (portion of phosphate in organic bonds was increased). This may be the basis of chlorosis-reverting effect of FeEDTA.     

Stoicheiometry of dicyclohexylcarbodiimide-ATPase interaction in mitochondria

1. The oligomeric dicyclohexylcarbodiimide (DCCD)-binding protein of mitochondrial ATPase was studied using (a) the relationship between [¹⁴C]DCCD binding and inhibition of ATPase activities and (b) the analysis of the kinetics of inhibition. 2. The [¹⁴C]DCCD binding to bovine heart mitochondria is linearly proportional to the inhibition of ATP hydrolysis up to a 50% decrease of the original activity resulting in 0.6 mol DCCD bound covalently to the specific inhibitory site (Hous?t?k, J., Svoboda, P., Kopecký, J., Kuz?ela, S?. and Drahota, Z. (1981) Biochim. Biophys. Acta 634, 331–339) per mol of the fully inhibited enzyme. 3. Kinetics of the inhibition of both the ATPase activity (heart and liver mitochondria) and ADP-stimulated respiration (liver) reveal that 1 mol DCCD per mol ATPase eliminates both the synthetic and the hydrolytic activities. It is inferred that the activity-binding correlation underestimates the number of DCCD-reactive sites. 4. The second-order rate constant of the DCCD-ATPase interaction (k) is inversely related to the concentration of membranes, indicating that DCCD reaches the inhibitory site by concentrating in the hydrophobic (phospholipid) environment. 5. At a given concentration of liver mitochondria, comparable k values are obtained both for the inhibition of ATP hydrolysis (k=5.35·10²M^?1·min^?1) and ADP-stimulated respiration (k=5.67·10²M^?1·min^?1). 6. It is concluded that both the synthetic and the hydrolytic functions of ATPase are inhibited via a common single DCCD-reactive site. This site is represented by one of the several polypeptide chains forming the oligomer of the DCCD-binding protein. The inhibitor-ATPase interaction does not exhibit cooperativity, indicating that the preferential reactivity towards DCCD is an inherent property of the inhibitory site.     

Neurons containing luteinizing hormone-releasing hormone in the indusium griseum of the rat

The authors detected LH--RH-containing neurons in the dorsal part of the hippocampus and in the indusium griseum of the rat. LH--RH-containing nerve fibres interconnect the organum subfornicale (OSF) and the dorsal hippocampus. Axons leaving the OSF can be traced backwards, then around the splenium of the corpus callosum, from where they run forwards in the stria longitudinalis medialis (SLM). LH--RH fibres of the SLM give axon collaterals to the cingulate cortex, then intermingle with the LH--RH system of the septum pellucidum. Following coronal transection of the SLM, it could be determined that LH--RH fibres form bidirectional connection between the septum and different regions of the hippocampus.     

Dictyostelium myosin II heavy-chain kinase A is activated by heparin, DNA and acidic phospholipids and inhibited by polylysine, polyarginine and histones.

Dictyostelium myosin II heavy-chain kinase A (MHCK A) is activated by autophosphorylation. Heparin and DNA, as well as vesicles composed of phosphatidylserine or phosphatidylinositol, were found to increase the initial rate of MHCK A autophosphorylation 5-10-fold in a Ca(2+)-independent manner. The negatively charged molecules also increased the activity of the autophosphorylated MHCK A by about 2-fold. In contrast, positively charged polypeptides such as poly(D-lysine), poly(L-lysine), poly(L-arginine) and histones strongly inhibited (IC50 of 0.5 micrograms/ml) the activity of the active, autophosphorylated MHCK A. Similar levels of inhibition, on a weight basis, were observed for poly(L-lysine) fractions with molecular weights from 3800 to 150,000-300,000. The inhibition was competitive with respect to peptide substrate and mixed with respect to ATP. At much higher concentrations poly(L-lysine) also inhibited the ability of MHCK A to autophosphorylate. It is proposed that negatively charged compounds and autophosphorylation increase the activity of MHCK A by weakening the interaction between the catalytic domain and a positively charged autoinhibitory domain.     

Surface immobilization of anchorage-dependent mammalian cells

Anchorage-dependent HeLa cells were successfully cultured on two fibrous materials (A07 and R100) with porosities of 75-125 and 40 mum, void fractions of 92% and 81%, and fiber diameters of 7.6 and 10.2 mum, respectively, in 100-mL spinner flasks and 2-L stirred tank bioreactors. The matrix was formed into a fixed vertical spiral configuration. All cultures displayed rapid (/=95%) to the matrix, uniform coverage of the immobilizing area with viable cells, and no significant amount of cell debris in the medium. Spinner flask cultures indicated that the denser material R100 showed better results in terms of final cell density. The growth of HeLa cells on material R100 in both culture systems was similar to that observed in tissue culture dishes (specific growth rate approximately 0.03-0.04 h(-1), maximum cell density of 8 x 10(6)-9 x 10(6) cells . mL(-1), and yields of 0.4 x 10(8) cells . mM(-1) on glucose and 2 x 10(8)-3 x 10(8) cells . mM(-1) on glutamine). Scale-up of this culture technique in a 2-L bioreactor under perfusion with pH and dissolved oxygen (DO) control yielded cell densities of up to 1.6 x 10(6) cells . mL(-1). Two other anchorage-dependent mammalian cells (ADC) known to be cultured with difficulty in roller bottles or with micro carriers were easily grown on material R100 in spinner flasks. The performance of this culture technique was compared to other ADC culture systems.