Altered light conditions following thinning affect xylem structure and potential hydraulic conductivity of Norway spruce shoots

Trees must respond to many environmental factors during their development, and light is one of the main stimuli regulating tree growth. Thinning of forest stands by selective tree removal is a common tool in forest management that increases light intensity. However, morphological and anatomical adaptations of individual shoots to the new environmental conditions created by thinning are still poorly understood. In this study, we evaluated shoot morphology (shoot length, needle number, projected leaf area) and anatomy (tracheid lumen area, tracheid number, tracheid dimensions, xylem area, potential hydraulic conductivity) in three Norway spruce (Picea abies/L./Karst.) families exposed to different thinning regimes. We compared shoot characteristics of upper-canopy (i.e. sun-exposed) and lower-canopy (i.e. shaded) current-year shoots in a control plot and a plot thinned to 50 % stand density the previous year. One tree per family was chosen in each treatment, and five shoots were taken per canopy position. We found that upper-canopy shoots in both plots had higher values than lower-canopy shoots for all studied parameters, except lumen roundness and tracheid frequency (i.e. tracheid number per xylem area). Thinning had little effect on shoot morphology and anatomy 1 year after thinning, except for small but significant changes in tracheid dimensions. Needles were more sensitive to altered light conditions, as projected leaf area of shoot, needle number and leaf hydraulic conductivity changed after thinning. Differences between upper- and lower-canopy shoots did not seem to be influenced by thinning and were almost the same in both plots. Our results suggest that lower-canopy shoots require several years to modify their morphology and anatomy to new light conditions following thinning. The slow light adaptation of the lower canopy may be of practical importance in forest management: thinned stands may be predisposed to drought stress because newly exposed shoots experience increased illumination and transpiration after thinning.     

Molecular weight of human gamma interferon is similar to that of other human interferons

The molecular weight (as determined by molecular sieve chromatography) of human gamma interferon, formerly referred to as immune or type II interferon, is between 40,000 and 70,000. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gamma interferon activity was recovered mainly from two regions of the gels corresponding to molecular weights of 20,000 and 25,000. The results suggest that in native form human gamma interferon may be aggregated.     

Small mammal responses to forest management for oak regeneration in southern Indiana

We used a 5-decade chronosequence of harvest openings to characterize population and community-level responses of small mammals to forest management targeting oak regeneration in southern Indiana. Live-trapping at 42 different sites allowed modeling of occupancy and relative abundance using environmental covariates while incorporating imperfect detection. Species richness was higher in smaller openings on southwest-facing aspects. Similarity between species richness of different age classes decreased with increasing site age. Eastern chipmunk (Tamias striatus) relative abundance was greater in early seral stages, i.e., at young sites with low basal areas. Relative abundance of white-footed mice (Peromyscus leucopus) exhibited different responses to coarse woody debris on sites versus microsites. Pine voles (Microtus pinetorum) and short-tailed shrews (Blarina brevicauda) were more likely to occupy older sites. We observed a greater relative abundance of short-tailed shrews at sites with steep and northeast-facing slopes. Northeast-facing slopes also resulted in higher short-tailed shrew occupancy rates. Incorporating detection probability enabled us to derive more accurate estimates of relative abundance and, when coupled with a Bayesian framework, permitted the estimation of occupancy for uncommon species. Our estimated responses can be used by forest managers to determine the potential impacts of even-aged and uneven-aged oak management on small mammals, and the statistical methodology we used can be applied even more broadly to improve understanding of wildlife responses to forest management.     

AIDS, drought, and child malnutrition in southern Africa

OBJECTIVE: To investigate trends in child malnutrition in six countries in southern Africa, in relation to the HIV epidemic and drought in crop years 2001/2 and 2002/3. DESIGN: Epidemiological analysis of sub-national and national surveys with related data.Setting: Data from Lesotho, Malawi, Mozambique, Swaziland, Zambia and Zimbabwe, compiled and analysed under UNICEF auspices. SUBJECTS: Secondary data: children 0-5 years for weight-for-age; HIV prevalence data from various sources especially antenatal clinic surveillance. RESULTS: Child nutritional status as measured by prevalence of underweight deteriorated from 2001 onwards in all countries except Lesotho, with very substantial increases in some provinces/districts (e.g. from 5 to 20% in Maputo (Mozambique, 1997-2002), 17 to 32% in Copperbelt (Zambia, 1999-2001/2) and 11 to 26% in Midlands province (Zimbabwe, 1999-2002)). Greater deterioration in underweight occurred in better-off areas. Areas with higher HIV/AIDS prevalences had (so far) lower malnutrition rates (and infant mortality rates), presumably because more modern areas--with greater reliance on trade and wage employment--have more HIV/AIDS. Areas with higher HIV/AIDS showed more deterioration in child nutrition. A significant area-level interaction was found of HIV/AIDS with the drought period, associated with particularly rapid deterioration in nutritional status. CONCLUSIONS: First, the most vulnerable may be households in more modern areas, nearer towns, to whom resources need to be directed. Second, the causes of this vulnerability need to be investigated. Third, HIV/AIDS amplifies the effect of drought on nutrition, so rapid and effective response will be crucial if drought strikes again. Fourth, expanded nutritional surveillance is now needed to monitor and respond to deteriorating trends. Finally, with or without drought, new means are needed of bringing help, comfort and assistance to the child population.     

Effect of Cobalt-Doped Framework on Formation of Todorokite from Layered Manganese Oxides with Mg~(2+)/Co~(2+) Ions as Template

Cobalt(Co)exists in significant quantities in naturally occurring manganese(Mn)oxides and alters the growth of Mn oxide crystals.Four-layered Mn oxides,Na-buserite(Na-bus)and three Co-doped Na-buserite samples prepared from oxidation of Mn(OH)2 with 5%,10%,and 20% Co/(Mn+Co)molar ratios(5Co-Na-bus,10Co-Na-bus,and 20Co-Na-bus),were used to prepare todorokite,a common Mn oxide on the Earth's surface,using Mg2+/Co2+ ions as a template.The results showed that todorokites could be obtained by reflux treatment of...     

Screen for anthelmintics, using larvae of Ascaris suum

A multiwell culture system was used to assay the effects of 12 known anthelmintic compounds on Ascaris suum larval development from 2nd-stage (L2; hatched from eggs) to early 3rd-stage (L3) and from in vivo-derived late L3 to early 4th-stage (L4). Larval survival, development, and motility were monitored for drug effects. Development of L2 to L3 was sensitive to thiabendazole, albendazole (ABZ), ABZ/sulfoxide, ABZ/sulfone (SO), mebendazole, L-tetramisole, D-tetramisole, piperazine, or closantel at a concentration of 0.01 microgram/ml; however, the effects of these drugs on larval development did not correlate well with known effects in vivo. The development of L3 to L4 was blocked by ABZ or mebendazole at 0.01 microgram/ml, by thiabendazole or ABZ/sulfoxide at 0.1 microgram/ml, and by ABZ/SO at 1.0 microgram/ml; however, except for ABZ/SO, most larvae were viable at these concentrations. In contrast, L-tetramisole or morantel appeared to inhibit development of L3 to L4 and to reduce survival at concentrations of greater than or equal to 1 microgram/ml; however, D-tetramisole was at least 10 times less effective. Haloxon, ivermectin, and closantel blocked development of L3 to L4 at 0.1, 1, and 10 micrograms/ml, respectively, in the absence of serum, but their activity was reduced by the presence of serum. Seemingly, in vitro development of A suum larvae was a convenient and sensitive bioassay for anthelmintic activity and could serve as a screen for anthelmintic residues in edible tissues.     

Retention and mobility of cations in a small peatland: trends and mechanisms

Inputs and net storage or release of cations can have a large impact on the acid-base balance of any ecosystem. Because of the absence of mineral soils, ion exchange and accretion in biomass are the major internal processes governing cation accumulation in peatlands. It is widely believed that peatlands have a large capacity to store cations, and thus to affect the acidity of surface waters. A long-term record of hydrologic and chemical inputs and outputs to the S-2 peatland in the Marcell Experimental Forest was used to construct annual and monthly mass balances for the four major cations. Bulk deposition and throughfall measurements suggest that deposition of Na, Ca and Mg has increased over the period 1971–1984; wet-only and dry bucket measurements do not show such a change. Seasonal and annual variations in cation inputs are not visible in the cation export from the peatland because the large cation reservoir on exchange sites in peat buffers the surface waters and prevents them from responding rapidly to changing inputs. Nevertheless, ion exchange represents a relatively minor source of acidity to this peatland, and accumulation of cations in woody biomass accounts for the majority of the cation retention. The major mechanism of retention in the peatland is different for each cation; accumulation in woody biomass is most important for Ca, storage on ion exchange sites in peat is most important for Mg, green plant tissues are the dominant site of K storage, and Na is bound by unknown mechanisms in the peat. Retention efficiencies show large annual variations but average 50% for Ca, 22% for Mg, 29–44% for Na, and 21% for K.     

三峡库区沿江农村城镇化问题研究

城镇化是三峡库区经济开发的必然选择,以三峡库区涪陵沿江地区农村城镇化问题为研究对象,深入地分析了沿江农村城镇化发展的主要问题与矛盾,并提出了相应的发展思路和对策。     

The role of organic vs. conventional farming practice,soil management and preceding crop on the incidence of stem-base pathogens on wheat

Journal of Plant Diseases and Protection - A stem-base disease complex of winter wheat includes several causal agents, such as eyespot (Oculimacula yallundae and O. acuformis), sharp eyespot...     

Preliminary Characterization of Extracellular Allelochemicals of the Toxic Marine Dinoflagellate Alexandrium tamarense Using a Rhodomonas salina Bioassay

Members of the marine dinoflagellate genus Alexandrium are known to exude allelochemicals, unrelated to well-known neurotoxins (PSP-toxins, spirolides), with negative effects on other phytoplankton and marine grazers. Physico/chemical characterization of extracellular lytic compounds of A. tamarense, quantified by Rhodomonas salina bioassay, showed that the lytic activity, and hence presumably the compounds were stable over wide ranges of temperatures and pH and were refractory to bacterial degradation. Two distinct lytic fractions were collected by reversed-phase solid-phase extraction. The more hydrophilic fraction accounted for about 2% of the whole lytic activity of the A. tamarense culture supernatant, while the less hydrophilic one accounted for about 98% of activity. Although temporal stability of the compounds is high, substantial losses were evident during purification. Lytic activity was best removed from aqueous phase with chloroform-methanol (3:1). A “pseudo-loss” of lytic activity in undisturbed and low-concentrated samples and high activity of an emulsion between aqueous and n-hexane phase after liquid-liquid partition are strong evidence for the presence of amphipathic compounds. Lytic activity in the early fraction of gel permeation chromatography and lack of activity after 5 kD ultrafiltration indicate that the lytic agents form large aggregates or macromolecular complexes.