Changes with starvation in the rat of the lipoprotein lipase activity and hydrolysis of triacylglycerols from triacylglycerol-rich lipoproteins in adipose tissue preparations.

Lipoprotein lipase activity was higher in fat-pad pieces than in isolated adipocytes from the same fed rats, whereas hydrolysis of triacylglycerols from triacylglycerol-rich lipoproteins was similar in the two preparations when incubated either in basal conditions or in the presence of heparin. In both preparations there was a similar release of lipoprotein lipase activity into the medium during basal incubation, enhanced by the presence of heparin. In fat-pad pieces, but not in isolated adipocytes, incubation with heparin produced a decrease in the lipoprotein lipase activity measured in the tissue preparation. In fat-pad pieces from 24 h-starved rats, lipoprotein lipase activity was the same as in isolated adipocytes from the same animals and incubation with heparin did not affect the appearance of lipoprotein lipase in the medium or the utilization of triacylglycerols from triacylglycerol-rich lipoproteins. These results support the following conclusions. (1) The effectiveness of lipoprotein lipase in adipose tissue preparations in vitro depends more on its availability to the substrate than on its total activity. (2) Heparin acts on adipose tissue preparations from fed animals both by enhancing the release of pre-existing extracellular enzyme (which is absent in isolated adipocytes) and by enhancing the transfer outside the cells of the intracellular (and mainly undetectable) enzyme that is activated in the secretion process. (3) In adipose tissue from starved animals there is not only a decrease in the active extracellular form of lipoprotein lipase activity but also a reduction in the intracellular (and mainly undetectable) pool of the enzyme.     

Role of molybdenum in nitrate reduction by chlorella

Molybdenum is absolutely required for the nitrate-reducing activity of the nicotinamide adenine dinucleotide nitrate reductase complex isolated from Chlorella fusca. The whole enzyme nicotinamide adenine dinucleotide nitrate reductase is formed by cells grown in the absence of added molybdate, but only its first activity (nicotinamide adenine dinucleotide diaphorase) is functional. The second activity of the complex, which subsequently participates also in the enzymatic transfer of electrons from nicotinamide adenine dinucleotide to nitrate (FNH₂-nitrate reductase), depends on the presence of molybdenum. Neither molybdate nor nitrate is required for nitrate reductase synthesis de novo, but ammonia acts as a nutritional repressor of the complete enzyme complex. Under conditions which exclude de novo synthesis of nitrate reductase, the addition of molybdate to molybdenum-deficient cells clearly increases the activity level of this enzyme, thus suggesting in vivo incorporation of the trace metal into the pre-existing inactive apoenzyme.     

Age and growth of yellow eels, Anguilla anguilla, in the estuary of the Guadalquivir river (south-west Spain)

A total of 1068 eels were examined from a population located in the Guadalquivir river estuary (37°N, 6°25'W). Maximum ages recorded were 4 + (males) and 7+ (females), and maximum lengths were 39-1 cm (males) and 54.1 cm (females). No growth was recorded between November and April, most occurring in May and, to a lesser extent, in June-October. Females grew to be larger than males. A classification analysis, based on 17 different European eel populations revealed that populations in brackish waters grew faster than those in fresh waters, but latitude also had an influence. Length-weight relationships obtained for three eel categories (males, females and undifferentiated) were used to estimate relative condition: condition cycles were similar between sexes, with increases in autumn and decreases in winter. There were monthly fluctuations in the sex ratio, and females dominated significantly in the combined catch (234 males/276 females).     

One step shoot tip multiplication and rooting of Digitalis thapsi L.

Shoot tips from seedlings of Digitalis thapsi L. were cultured on Murashige and Skoog's medium and the effect of various auxins (2,4-D, NAA and IAA) were analyzed alone or in combination with cytokinis (BA and kinetin). Shoot multiplication and direct rooting of the new shoots were obtained after four weeks of culture in MS medium without hormones, but callus formation and the appearance of abnormal phenotypes were frequent. The addition of auxins to the cultures prevented the formation of callus but not the appearance of variant phenotypes. Both drawbacks could be avoided by combination of NAA or IAA with BA or kinetin. The best results for shoot multiplication and direct rooting were obtained with 0.5 mg l^-1 NAA and 0.1 or 0.5 mg l^-1 kinetin.Abbreviations BA 6-benciladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - Kin kinetin - NAA naphtalene acetic acid - MS Murashige and Skoog     

Genetic variation of recent Alu insertions in human populations

The Alu family of intersperesed repeats is comprised of ovr 500,000 members which may be divided into discrete subfamilies based upon mutations held in common between members. Distinct subfamilies of Alu sequences have amplified within the human genome in recent evolutionary history. Several individual Alu family members have amplified so recently in human evolution that they are variable as to presence and absence at specific loci within different human populations. Here, we report on the distribution of six polymorphic Alu insetions in a survey of 563 individuals from 14 human population groups across several continents. Our results indicate that these polymorphic Alu insertions probably have an African origin and that there is a much smaller amount of genetic variation between European populations than that found between other populations groups. Present address: Department of Pathology, Stanley S. Scott Cancer Center, Louisiana State University Medical Center, 1901 Perdido St., New Orleans, LA 70112 Correspondence to: M.A. Batzer     

Cloning and expression of the Neisseria meningitidis 5C outer membrane protein

The 5C outer membrane protein, one of the N. meningitidis class 5 proteins, was preferably expressed in bacteria isolated from the nasopharynx and its role in adhering to the mucosal cells and invading them as well as the development of anti-5C antibodies in healthy carriers was demonstrated. Anti-5C monoclonal antibodies are bactericidal in the presence of the human complement. The immunodominant region of the 5C protein is highly conserved among the different strains of N. meningitidis, and the opc gene, which encodes the protein, does not seem to show antigenic variations. Here the isolation of the opc gene from the Cuban strain B:4:P1.15 by PCR (Polymerase Chain Reaction) is presented. Under the regulation of the tryptophan promoter, the gene was cloned and sequenced in E. coli with a high level of expression and fused to the amino-terminal end of the interleukin-2 gene. In the dot-blot experiments, the presence of the gene in those strains which did not express the protein in the whole cell ELISA was also detectable.     

The age, growth and reproduction of Chondrostoma polylepis willkommi in a seasonal stream in the Guadalquivir River basin (southern Spain)

The age, growth and reproduction of Chondrostoma polylepis willkommi , an endemic cyprinid from the Iberian Peninsula, was studied for 2 years in a seasonal stream in the Guadalquivir River basin. Annual growth was low. Maximum ages observed were 5+ in males and 7+ in females. There was no significant difference in growth between sexes. Seasonal growth period started in May and continued for 2 to 6 months depending on age. The mean lengths of 1 + and 2+ age-groups decreased once the growth period had finished, probably related to reproductive stress and adverse ecological conditions, and this could explain the occurrence of Rosa Lee's phenomenon. Both sexes matured at the end of their second year of life (1+). There was a significant difference from 1: 1 in the overall sex ratio of 334 males to 464 females. Reproductive period started in March and lasted until May. Ch. p. willkommi was a multiple spawner that released two batches of eggs per female each year. The regression between fecundity ( F ) and fork length (l., mm) was: F =6.20 10³ L.^2.78. In females from age 2 + onwards, relative annual investment in somatic growth and reproduction was equivalent, implying that the same energy was allocated to reproduction as to maintenance/growth. Compared with other Ch. polylepis populations, the life-history patterns of this population, located in a small and seasonal stream in a southern latitude, were characterized by a low annual growth, a trade-off between reproduction and growth/maintenance, early maturity, low number of age-groups and high fecundity from multiple spawnings.