Gas exchange and resource-use patterns along a Mediterranean successional gradient

Abstract. Gas exchange, leaf-nitrogen concentration and water potential were measured in early and late spring in early successional herbaceous plants occurring after cutting and after fire, and in mature woody species from the Mediterranean climax community Quercetum ilicis in central Italy. Net photosynthesis peaked in early spring in all species studied when values for temperature and light were lower but leaf-nitrogen content was higher as compared to late spring, suggesting that nitrogen more than energy input controlled photosynt-hetic rates. Herbaceous pioneer species occurring after cutting showed higher field photo synthetic capacity than evergreen climax trees and shrubs. By contrast, net photosynthesis of herbaceous species occurring in a persistent stage after fire, was in the same range as that of climax trees. This evidence suggests that carbon-gaining appears to be partly related to the dynamic stage of succession and not solely to the growth form.     

The application of linear irreversible thermodynamics to biological growth

We measured the rate of cell biomass growth, the consumption of organic substrate, and the heat developed during growth. The relationship between thermodynamic efficiency and the rate of microbial growth was considered.     

Growth and pubertal development during and after treatment with a slow-release gonadotropin-releasing hormone agonist in central precocious puberty.

The auxological data of 25 patients (21 girls, 4 boys) with central precocious puberty (CPP), treated for 4 years with a slow-release gonadotropin-releasing hormone agonist [Decapeptyl-controlled release (D-CR) 3.75] every 4 weeks intramuscularly, and of 6 patients (3 girls, 3 boys), treated for 5 years, are presented. After 3 years of D-CR a stabilization of height velocity (HV) at about 4 cm/year was observed. Bone maturation (ratio of change in bone age to change in chronological age; delta BA/delta CA) slowed down to a mean delta BA/delta CA ratio of 0.5 +/- 0.2 (mean +/- SD) measured over 48 months. As a result, predicted adult height (PAH) improved from 156.3 +/- 7.4 to 162.2 +/- 6.8 cm in girls (p less than 0.001) and from 174.4 +/- 18.6 to 184.3 +/- 17.1 cm in boys after 4 years. In the 5th year an ongoing improvement of PAH was observed. 20 additional girls discontinued D-CR for at least 12 months after treatment with D-CR for 2 years or more. In 11 girls menses started after 10.6 +/- 3.1 months; 9 girls had no menarche after 12-16 months. HV increased in the first and second 6 months to a level of about 6.0 cm/year, decreased in the third 6 months after cessation to the level before discontinuing D-CR and decreased further afterwards. Bone maturation (delta BA/delta CA) increased progressively in the first 18 months after discontinuation, with a stabilization at about 1.3. PAH did not change in the first 12 months after discontinuation of D-CR, but showed a decrease afterwards.(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency of abnormal human haemoglobins caused by C----T transitions in CpG dinucleotides

A large part of human genetic disease apparently arises from deamination of cytosines in methylated CpG dinucleotides. Their mutation rate is known to be high when C is present as 5-methylcytosine, but is believed to be normal when it is unmethylated. The beta-globin gene contains five, the gamma-globin gene two, and each of the alpha-globin genes contain 35 CpGs. The CpGs in the beta- and gamma-globin genes are methylated, while those in the alpha-globin genes are undermethylated. One would therefore have expected the CpGs to be a frequent source of mutations in the beta- and gamma-globin genes, but not in the alpha-globin genes. In fact, the evidence points to CpGs being a frequent source of mutations in both the alpha- and beta-globin genes. This suggests either that the mutation rates of both methylated and unmethylated CpGs are abnormally high, which conflicts with published evidence, or that there is a finite chance of some CpGs in the alpha-globin genes of certain individuals being methylated and therefore subject to mutation.     

Oogenesis in the Apogamous Fern Pteris cretica

The events that characterize egg formation and maturation inPteris cretica were investigated using transmission electronmicroscopy and electron microscope microprobe analysis. Theydid not differ significantly from those described for sexuallyreproducing ferns. The significance of these findings is discussedin relation to current theories concerning phase change in ferns. Pteris cretica, fern, apogamy, agamospory, transmission electron microscopy, oogenesis     

Purification and partial characterization of a bovine epidermal growth factor-like polypeptide

A heterologous radioreceptor assay was developed to follow the purification of an EGF-like polypeptide from bovine kidney. Purification of the growth factor was facilitated by the use of a novel affinity column using fixed A431 cells attached to sephadex beads. The mol. wt. of the purified EGF-LP was estimated to be 5480 from the amino acid composition. The purified EGF-like polypeptide stimulated the proliferation of bovine mammary epithelial cells and appeared to be equipotent to mouse EGF. Available evidence suggests that the purified molecule is distinct from bovine TGF-alpha.     

Biotransformation of 2,2-Dimethyl-1,3-Propanediol to 3-Hydroxypivalic Acid by Acetobacter Acetii DSMZ3508 and Related Bacteria

Acetobacter acetii DSMZ3508 and related bacteria converted 2,2-dimethyl-1,3-propanediol into 3-hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid; 3HP) during submerged cultivation in mineral salt medium. The maximum yield of 3-hydroxypivalic acid was 24.4% of the fed substrate after 18 days. Cultivation parameters, as pH, cell density, optimal substrate concentration, and oxygen supply for the bioconversion process were determined.     

Lactate from cultures of Lactobacillus casei recovered in a fluidized bed column using ion exchange resin

Summary Lactic acid produced by continuous culture of L.casei in an upflow packed bed reactor, was recovered with Amberlite IRA 400 in a fluidized bed column. Bed expansions of 1.25 and 2.25 were applied. Reutilization did not alter the capability of net recovery of 0.048 ± 0.01 g lactic acid/g resin. When 2200 cm/h of ascensional velocity was used, (bed expansion of 2.25), the resin adsorbed 39.3% of the initial lactic acid and 63.5% was eluted. This resin supported the highest exchange capacity of 0.126 g lactic acid/g resin. Applying high flow rates, the process has potential industrial applications due to the short time employed.