Changes in heated and autoclaved forest soils of S.E. Australia. I. Carbon and nitrogen

The effect of heating and autoclaving on extractable nitrogen, N mineralisation and C metabolism was studied by heating five forest soils in the laboratory, simulating the range of effects of heat due to bushfire. Top soil (0–5 cm) was heated to 60 °C, 120 °C and 250 °C for 30 minutes; unheated soil was taken as a control. Samples of the soil heated to 250 °C were also inoculated with fresh soil to accelerate the recovery of the microbial population. Soil autoclaving was carried out as another heat treatment (moist heat). Soils were analysed immediately after heating and 3 times during seven months of incubation to assess immediate and longer-term effects of heating.Extractable N (organic and mineral forms) increased after heating to 120 °C, but decreased with further heating to 250 °C suggesting the volatilisation of N. N associated with microbial biomass diminished with heating and was barely detectable after the 250 °C treatment. Microbial biomass was an important source of soluble N in heated soils, and only partly recovered during subsequent long incubation. The amount of N mineralised during incubation depended on both soil and temperature. Nitrification did not occur when soils were heated to 250 °C (with or without inoculum), or after autoclaving, demonstrating the high sensitivity of nitrifiers to heat. At the beginning of soil incubation, respiration was enhanced in heated soils (250 °C, 250 °C inoculated) and autoclaved soils, but after 30 days of incubation respiration decreased to values either similar to or lower than those in control. This respiration pattern indicated that a fraction of labile C was released by heating, which was quickly mineralised within 30 days of incubation. These results demonstrate some effects of soil heating on C and N dynamics in forest soils.     

Actions and interactions of growth hormone and insulin-like growth factor-II: body and organ growth of transgenic mice

To characterize long-term actions and interactions of growth hormone (GH) and insulin-like growth factor-II (IGF-II) on postnatal body and organ growth, hemizygous phosphoenolpyruvate carboxykinase (PEPCK)-human IGF-II transgenic mice were crossed with hemizygous PEPCK-bovine GH transgenic mice. The latter are characterized by two-fold increased serum levels of IGF-I and exhibit markedly increased body, skeletal and organ growth. Four different genetic groups were obtained: mice harbouring the IGF-II transgene (I), the bGH transgene (B), or both transgenes (IB), and non- transgenic controls (C). These groups of mice have previously been studied for circulating IGF-I levels (Wolf et al., 1995a), whereas the present study deals with body and organ growth. Growth curves (week 3 to 12) were estimated by regression with linear and quadratic components of age on body weight and exhibited significantly (p < 0.001) greater linear coefficients in B and IB than in I and C mice. The linear coefficients of male I and C mice were significantly (p < 0.001) greater than those of their female counterparts, whereas this sex-related difference was absent in the bGH transgenic groups. The weights of internal organs as well as the weights of abdominal fat, skin and carcass were recorded from 3.5- to 8- month-old mice. In addition, organ weight-to-body weight-ratios (relative organ weights) were calculated. Except for the weight of abdominal fat, absolute organ weights were as a rule significantly greater in B and IB than in I and C mice. IGF-II overproduction as a tendency increased the weights of kidneys, adrenal glands, pancreas and uterus both in the absence and presence of the bGH transgene. Analysis of relative organ weights demonstrated significant (p < 0.05) effects of elevated IGF- II on the relative growth of kidneys (males and females) and adrenal glands (females), confirming our previous report on organ growth of PEPCK-IGF-II transgenic mice. In females, IGF-II and GH overproduction were additive in stimulating the growth of spleen and uterus, providing evidence for tissue-specific postnatal growth promoting effects by IGF-II in the presence of elevated IGF-I     

Experimental Indication in Favor of the Introns-Late Theory: The Receptor Tyrosine Kinase Gene from the Sponge Geodia cydonium

We have analyzed the gene that encodes receptor tyrosine kinase (RTK) from the marine sponge Geodia cydonium, which belongs to the most ancient and simple metazoan groups, the Porifera. RTKs are enzymes found only in metazoa. The sponge gene contains two introns in the extracellular part of the protein. However, the rest of the protein (transmembrane and intracellular part), including the tyrosine kinase (TK)-domain, is encoded by a single exon. In contrast, all TK genes, so far known only from higher animals (vertebrates), contain several introns especially in the TK-domain. The TK-domain of G. cydonium shows similarity with numerous members of receptor as well as nonreceptor TKs. Phylogenetic analysis of the sponge TK-domain indicates that this enzyme branched off first from the common tree of metazoan TK proteins. Consequently, we assume that introns, found in the TK-domains of genes from higher animals, were inserted into these genes after splitting off the sponge taxa from other metazoan organisms (over 600 million years ago). Our results support the view that ancient genes were not ``in pieces.' Received: 8 August 1996 / Accepted: 4 November 1996     

Anti-Hepatitis A Virus Antibody Response Elicited in Mice by Different Forms of a Synthetic VP1 Peptide

Peptide VP1 (11-25) of the capsid of hepatitis A virus was synthesized by the Fmoc-polyamide solid phase method, and administered to mice in different forms: (1) free, (2) encapsulated in multilamellar liposomes, (3) coupled to keyhole limpet hemocyanin (KHL), and (4) incorporated into a tetrameric branched lysine core. The highest anti-VP1 peptide responses were generated by synthetic peptides entrapped into liposomes and coupled to KLH. No anti-HAV response was generated with the free peptide, while all the other forms induced both anti-HAV and HAV-neutralizing antibodies. Maximum neutralization indices were observed in ascites from mice treated with liposome-entrapped and KLH peptides.     

Evidence from charcoal analysis for environmental change during the interval late Bronze Age to Roman,at the archaeological site of Castro de Penices,N.W. Portugal

Vegetation and environmental change from late Bronze Age to the Roman period in north-west Portugal is reconstructed on the basis of charcoal analyses. The site was occupied by people of the Castrejo culture, i.e. an Iron Age culture that developed in the north-west Iberian peninsula. The pattern of exploitation of natural wood resources by local populations during this period appears to be similar during the three phases of occupation. The frequencies of light-demanding plant species, mostly Leguminosae, testify to considerable destruction and degeneration of the climax woodlands. The preference of particular wood for specific uses, such as roofing, is discussed and the Holocene history of selected trees within the wider region is considered.     

Fluorescence of eosinophil leucocyte granules induced by 1-hydroxy-3,6,8-pyrenetrisulfonate. Visualization of differences in protein isoelectric points

After treatment of horse, rat and human blood smears with alkaline solutions of 1-hydroxy-3,6,8-pyrenetrisulfonate (HPTS), eosinophil leucocyte granules were the unique cell components which showed a bright green fluorescence. When stained with HPTS at pH 10, the whole granule of horse eosinophils showed high emission which strongly diminished after washing or staining in salt solutions or by using blocking methods for amino groups. Using HPTS at pH 12, the fluorescence reaction of house granules was specifically located in the peripheral region, appearing as fluorescent rings. These microscopic observations, which indicate differences in the isoelectric point of proteins within the eosinophil granule, were also confirmed by HPTS staining of protein blots as model substrates. Spectral analysis of HPTS at pH 10 and 12 showed practically identical absorption and emission spectra with peaks at 450 nm and 510 nm, respectively. Our results indicate that mainly ionic binding occurs between cationic proteins and HPTS in alkaline solution, and that the most cationic proteins (with isoelectric points at pH higher than 12) are located in the peripheral annular region of horse eosinophil granules.