Importance of disturbance history on net primary productivity in the world's most productive forests and implications for the global carbon cycle

Analysis of growth and biomass turnover in natural forests of Eucalyptus regnans, the world's tallest angiosperm, reveals it is also the world's most productive forest type, with fire disturbance an important mediator of net primary productivity (NPP). A comprehensive empirical database was used to calculate the averaged temporal pattern of NPP from regeneration to 250 years age. NPP peaks at 23.1 ± 3.8 (95% interquantile range) Mg C ha^?1 year^?1 at age 14 years, and declines gradually to about 9.2 ± 0.8 Mg C ha^?1 year^?1 at 130 years, with an average NPP over 250 years of 11.4 ± 1.1 Mg C ha^?1 year^?1, a value similar to the most productive temperate and tropical forests around the world. We then applied the age‐class distribution of E. regnans resulting from relatively recent historical fires to estimate current NPP for the forest estate. Values of NPP were 40% higher (13 Mg C ha^?1 year^?1) than if forests were assumed to be at maturity (9.2 Mg C ha^?1 year^?1). The empirically derived NPP time series for the E. regnans estate was then compared against predictions from 21 global circulation models, showing that none of them had the capacity to simulate a post‐disturbance peak in NPP, as found in E. regnans. The potential importance of disturbance impacts on NPP was further tested by applying a similar approach to the temperate forests of conterminous United States and of China. Allowing for the effects of disturbance, NPP summed across both regions was on average 11% (or 194 Tg C/year) greater than if all forests were assumed to be in a mature state. The results illustrate the importance of accounting for past disturbance history and growth stage when estimating forest primary productivity, with implications for carbon balance modelling at local to global scales.     

Characteristics of Eliciting Effects of Furostanol Glycosides on Cultured Yam Cells

To unravel mechanisms of elicitor action of furostanol glycosides (FGs), the formation of superoxide anion after the addition of FGs to a suspension culture of yam (Dioscorea deltoidea Wall. ex Griseb) cells was studied. The substantial increase in superoxide level, evaluated by nitroblue tetrazolium (NBT) reduction to formazan, was found at the exponential phase of cell growth. The involvement of NADPH oxidase in the superoxide generation was revealed by means of inhibitory analysis. Diphenyliodonium chloride (DPI), the inhibitor of NADPH oxidase, compromised the action of FGs. Meanwhile, the elimination of apoplastic peroxidase did not affect the accumulation of formazan, which suggests the involvement of NADPH oxidase but not peroxidase in the superoxide generation. In addition to NBT-test, the superoxide formation was judged by changes in activity of superoxide dismutase (SOD). Exogenous FGs activated the enzyme due to the increased production of superoxide anion. In this case, DPI decreased SOD activity that conforms to the NADPH oxidase involvement in the superoxide generation. The analysis of antioxidant activity of FGs by inhibition of radicals of 2,2-diphenyl-1-picrylhydrazyl showed that FGs are weak reductants in comparison with ascorbic acid. The results of the work allow for the suggestion that, supposing a weak reducing capacity of FGs, the special feature of their exogenous action on cultured yam cells is the increase in the level of superoxide anion radical mainly produced by NADPH oxidase.     

Chromosomal rearrangements with a common breakpoint at 6p23 in five cases of myeloid leukemia

Rearrangement of the short arm of chromosome 6 with a breakpoint at 6p23 was found in five patients with myeloid leukemia. Three of them had different morphological variants of AML (M2, M3, M4) and two blastic crisis of Ph1 negative and Ph1 positive CML. Identical translocation, t(6;9)(p23;q34), was revealed in two patients. One of them had AML (M2), the other blastic crisis of Ph1 negative CML. The blast cells of the last patient were morphologically similar to those in the M2 variant of AML. Translocation (6;9)(p23;q34) was also detected in two AML patients of Rowley and Potter (1976). The role of the breakpoint at 6p23 in myeloid malignancies needs further investigation.     

Study of intervesicular phospholipid exchange by NMR

NMR spectroscopy with the use of non-penetrating paramagnetic probes permits in situ determination of the composition of the outer surface of phospholipid vesicles. The method was employed to follow the phospholipid exchange between phosphatidylinositol and phosphatidylcholine vesicles induced by a postmicrosomal protein fraction from rat liver. The effects of these proteins on the lipid bilayer and the structure of the vesicles produced by exchange were studied.     

Chromosomes in acute nonlymphocytic leukemia

Summary The karyotype of leukemic cells was studied in 88 acute nonlymphocytic leukemia (ANLL) patients. Chromosome abnormalities were discovered in 78.4% of all patients and in 72.5% of the 69 patients studied before treatment. Characteristic abnormalities: translocations 8;21, 15;17, 9;22 or 6;9, rearrangements of 11q, gain of chromosomes 8 or 21, and loss or deletion of chromosomes 5 or 7 were detected in 56 of 69 patients with abnormal karyotypes. Translocation 8;21 was revealed in 27 patients; 20 of them had M2 FAB-form, four had M1, and three had M4. In patients with t(8;21) the incidence of complete remission was higher and the duration of first remission and survival longer than in patients with other abnormalities or with a normal karyotype.     

Structure of tryptic fragments of a neurotoxin from black widow spider venom

The N-terminal amino acid sequence of a neurotoxin from the venom of Latrodectus mactans tredecimguttatus (alpha-latrotoxin) was determined. Latrotoxin was subjected to the tryptic cleavage and total or partial amino acid sequences of 25 peptides were established. In total the tryptic fragments contained 252 amino acid residues. Essential structural information on cloning of the latrotoxin structural gene was obtained.     

Combined action of nicotinamide and adenine in preservation of packed red cells

An alkaline resuspension solution "Erythronaph" with adenine and nicotinamide has been developed. It allows to preserve red blood cells for 35 days. Removing leukocytes and platelets up to 90% by brief warning of 24-hour blood prior to centrifugation combined with return of 10% of plasma provide further prolongation of storage of red blood cells in "Erythronaph".     

Bis(adenosyl-5′)tetraphosphate as a partial agonist of ATP receptors in rat sensory neurons

The effects of bis(adenosyl-5)oligophosphates on cation conductance-promoting ATP receptors at the somatic membrane of rat sensory ganglia neurons were investigated. Both bis(adenosyl-5)tetraphosphate and bis(adenosyl-5)pentaphosphate act as partial agonists of ATP receptors at saturating concentration and activate ionic currents of almost one order of magnitude below the amplitude of peak ATP-activated currents. Combined application of these two substances to the neuron produces a considerable decline in the amplitude of ATP-activated ionic currents, competing with ATP for common binding sites.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 4, pp. 427–431, July–August, 1988.     

Chinese hamster cells mutant at the hypoxanthine-guanine phosphoribosyltransferase (GPRT) locus. V. Complementation analysis of ts mutants

Four temperature-sensitive HPRT clones were used for hybridological analysis, which led to increase in complementation rate about 5 times. The probability of complementation, in respect of the HPRT locus proved to be rather high: 14 of 45 hybridization-tested mutants had complementation ability (including 3 ts mutants). Analysis of the complementation rate among mutants revealed clear-cut dependence on the selection conditions: clones grown in a medium with 8-azaguanine showed most frequent complementation. The use of mutants with a new phenotype in hybridization analysis revealed four additional complementation groups, three of which are made of temperature-sensitive clones. Biochemical analysis revealed the presence of hybrid forms of the HPRT enzyme in all hybrids tested. This confirms the intragenic character of complementation. At present, the functional map of the HPRT locus is represented by 9 groups, including a group of mutants with no complementation ability.     

Changes in the activity of antioxidizing enzymes during spermatogenesis

A study was made of variation in the activity of the antioxidant defense system enzymes superoxide dismitase (SOD), glutathione peroxidase, (GP) and glutathione-S-transferase (GT) in the cells of mouse spermatogenic epithelium. The cells were fractionated in the gradient of human serum albumin using the STAPUT system. SOD activity was comparable to that in liver cells, that of GP was one order to magnitude lower, and that of GT one order of magnitude higher than in the liver. Differentiation of spermatogenic cells demonstrated phase variations in the activity of these enzymes, with a maximum seen at the stage of late pachytene spermatocytes. SOD, GP and GT activities were discovered to be reduced in postmeiotic cells (early spermatid fractions) by 2.8-3.5; 1.9-2.3 and 4.2-5.6 times, respectively. That reduction was followed by activation of the enzymes at the late stages of spermiogenesis.