Novel prolactin related mRNAs in rat pituitary cells

From cytoplasm of rat pituitary GH4C1 tumour cells, anti prolactin anti-serum precipitates a polypeptide with apparent molecular weight of 75.000 in addition to prolactin. In vitro translation of size fractionated RNA shows that a 82.000 molecular weight PRL-like polypeptide is encoded by a mRNA larger than the 1 kb prolactin mRNA. Northern blot analysis shows that a rat prolactin cDNA probe hybridize to a 3.2 kb RNA and a 1.5 kb RNA in addition to the 1 kb PRL mRNA. The 82.000 molecular weight translation product and the 3.2 kb mRNA is also detected in rat anterior pituitary cytoplasm. We conclude that at least one high molecular weight mRNA which code for a prolactin-like polypeptide, is present in normal rat anterior pituitary gland and in GH4C1 cells.     

High expression of functional adenovirus DNA polymerase and precursor terminal protein using recombinant vaccinia virus.

Initiation of Adenovirus (Ad) DNA replication occurs by a protein-priming mechanism in which the viral precursor terminal protein (pTP) and DNA polymerase (pol) as well as two nuclear DNA-binding proteins from uninfected HeLa cells are required. Biochemical studies on the pTP and DNA polymerase proteins separately have been hampered due to their low abundance and their presence as a pTP-pol complex in Ad infected cells. We have constructed a genomic sequence containing the large open reading frame from the Ad5 pol gene to which 9 basepairs from a putative exon were ligated. When inserted behind a modified late promoter of vaccinia virus the resulting recombinant virus produced enzymatically active 140 kDa Ad DNA polymerase. The same strategy was applied to express the 80 kDa pTP gene in a functional form. Both proteins were overexpressed at least 30-fold compared to extracts from Adenovirus infected cells and, when combined, were fully active for initiation in an in vitro Adenovirus DNA replication system.     

Ethylene as a possible mediator of light-induced inhibition of root growth

Eliasson, L. and Bollmark, M. 1988. Ethylene as a possible mediator of light-induced inhibition of root growth. - Physiol. Plant. 72: 605–609.
Pea seedlings ( Pisum sativum L. cv. Weibull's Marma) were used to investigate the possible role of ethylene in light-induced inhibition of root elongation. Illumination of the roots with white light inhibited root elongation by 40–50% and increased ethylene production by the roots about 4-fold. Our main approach was to use exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), supplied in the growth solution, to monitor ethylene production of the roots independent of light treatment. Ethylene production of excised root tips increased with increasing ACC concentrations. The rate of ethylene production in dark-grown roots treated with 0.1 μ M ACC was similar to that caused by illumination. Low ACC concentrations (0.01–0.1 μ M ) decreased the rate of root elongation, especially in seedlings grown in the dark, and 0.1 μ M ACC inhibited elongation to about the same extent as light. In light the roots curved and grew partly plagiogravitropically. This effect was also simulated by the 0.1 μ M ACC treatment. At 1 μ M and higher concentrations, ACC inhibited root growth almost completely and caused conspicuous curvatures of the root tips both in light and darkness. Inhibitors of ethylene synthesis and action partially counteracted the inhibition of root elongation caused by light. These observations suggest that the increase in ethylene production caused by light is at least partly responsible for the decreased growth of light-exposed roots.     

A classification of the Monimiaceae

Thirty-two genera of the Monimiaceae are assigned to six subfamilies and eight tribes. Two further genera are insufficiently known to be placed. One subfamily (Glossocalycoideae Thorne, two tribes (Hennecartieae Philipson, Palmerieae Philipson) and one genus ( Laureliopsis Schodde) are described as new.     

Pyrimidine,purine and nitrogen control of cytosine deaminase synthesis in Escherichia coli K12. Involvement of the glnLG and purR genes in the regulation of codA expression

Cytosine deaminase, encoded by the codA gene in Escherichia coli catalyzes the deamination of cytosine to uracil and ammonia. Regulation of codA expression was studied by determining the level of cytosine deaminase in E. coli K12 grown in various defined media. Addition of either pyrimidine or purine nucleobases to the growth medium caused repressed enzyme levels, whereas growth on a poor nitrogen source such as proline resulted in derepression of cytosine deaminase synthesis. Derepression of codA expression was induced by starvation for either uracil or cytosine nucleotides. Nitrogen control was found to be mediated by the glnLG gene products, and purine repression required a functional purR gene product. Studies with strains harbouring multiple mutations affecting both pyrimidine, purine and nitrogen control revealed that the overall regulation of cytosine deaminase synthesis by the different metabolites is cumulative.This paper is dedicated to Professor John Ingraham, Department of Bacteriology, University of California, Davis, on the occasion of his retirement, in recognition of his many contributions in the field of bacterial growth and metabolism     

High quality cord blood banking is feasible with delayed clamping practices. The eight-year experience and current status of the national Swedish Cord Blood Bank

The National Swedish Cord Blood Bank (NS-CBB) is altruistic and publicly funded. Herein we describe the status of the bank and the impact of delayed versus early clamping on cell number and volume. Cord Blood Units (CBUs) were collected at two University Hospitals in Sweden. Collected volume and nucleated cell content (TNC) were investigated in 146 consecutive Cord Blood (CB) collections sampled during the first quarter of 2012 and in 162 consecutive CB collections done in the first quarter of 2013, before and after clamping practices were changed from immediate to late (60 s) clamping. NS-CBB now holds close to 5000 units whereof 30 % are from non-Caucasian or mixed origins. Delayed clamping had no major effect on collection efficiency. The volume collected was slightly reduced (mean difference, 8.1 ml; 95 % CI, 1.3–15.0 ml; p = 0.02), while cell recovery was not (p = 0.1). The proportion of CBUs that met initial total TNC banking criteria was 60 % using a TNC threshold of 12.5 × 10⁸, and 47 % using a threshold of 15 × 10⁸ for the early clamping group and 52 and 37 % in the late clamping group. Following implementation of delayed clamping practices at NS-CBB; close to 40 % of the collections in the late clamping group still met the high TNC banking threshold and were eligible for banking, implicating that that cord blood banking is feasible with delayed clamping practices.     

Functional comparison of the three isoforms of the Na+/Ca2+ exchanger (NCX1, NCX2, NCX3)

Three distinctmammalianNa⁺/Ca²⁺exchangers have been cloned: NCX1, NCX2, and NCX3. We have undertaken adetailed functional comparison of these three exchangers. Eachexchanger was stably expressed at high levels in the plasma membranesof BHK cells. Na⁺/Ca²⁺exchange activity was assessed using three different complementary techniques: Na⁺ gradient-dependent⁴⁵Ca²⁺uptake into intact cells, Na⁺gradient-dependent⁴⁵Ca²⁺uptake into membrane vesicles isolated from the transfected cells, andexchange currents measured using giant patches of excised cellmembrane. Apparent affinities for the transported ionsNa⁺ andCa²⁺ were markedly similar for thethree exchangers at both membrane surfaces. Likewise, generally similarresponses to changes in pH, chymotrypsin treatment, and application ofvarious inhibitors were obtained. Depletion of cellular ATP inhibitedNCX1 and NCX2 but did not affect the activity of NCX3. Exchangeactivities of NCX1 and NCX3 were modestly increased by agents thatactivate protein kinases A and C. All exchangers were regulated byintracellular Ca²⁺. NCX1-inducedexchange currents were especially large in excised patches and, likethe native myocardial exchanger, were stimulated by ATP. Results may beinfluenced by our choice of expression system and specific splicevariants, but, overall, the three exchangers appear to have verysimilar properties.

     

Ontogenetic Scaling of Foraging Rates and the Dynamics of a Size-Structured Consumer-Resource Model

The ontogenetic scaling of foraging capacity strongly influences the competitive ability of differently sized individuals within a species. We develop a physiologically structured model to investigate the effect of different ontogenetic size scalings of the attack rate on the population dynamics of a consumer-resource system. The resource is assumed to reproduce continuously whereas the consumer only reproduces at discrete time instants. Depending on the ontogenetic size scaling, the model exhibited recruit-driven cycles, stable fixed point dynamics, non-recruit juvenile-driven cycles, quasiperiodic orbits, or chaotic dynamics. The kind of dynamics observed was related to the maintenance resource levels required of differently sized individuals. Stable fixed point dynamics was, besides at the persistence boundary, only observed when the minimum resource levels were similar for newborns and mature individuals. The tendency for large population fluctuations over a wide range of the parameter space was due to the consumer's pulsed reproduction. Background mortality and length of season were major determinants of cycle length. Model dynamics strongly resembled empirically observed dynamics from fish and Daphnia populations with respect to both patterns and mechanisms. The non-recruit juvenile-driven dynamics is suggested to occur in populations with size-dependent interference or preemptive competition like cicada populations.