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951.
Lian Pin Koh 《Biodiversity and Conservation》2007,16(13):3935-3938
Here, I report on how forest area in Southeast Asia has changed for different types of forest and across different countries
between the periods of 1990–2000 and 2000–2005. The loss of old growth forests has accelerated in Indonesia, Cambodia and
Vietnam but have ceased in Thailand, Malaysia, Laos and the Philippines. Secondary forests continue to be lost in Malaysia,
Cambodia, Laos, Myanmar, Indonesia, Thailand and the Philippines. Plantation forests have increased in area by 25.0% from
1990 to 2005 but still comprise only 6.2% of the total forest area in Southeast Asia. Overall, the loss of native forests
(old growth and secondary forests) has slowed down in Thailand, the Philippines and Brunei but has worsened in Laos, Myanmar,
Indonesia, Malaysia and Cambodia. 相似文献
952.
953.
Py B Bouchet J Jacquot G Sol-Foulon N Basmaciogullari S Schwartz O Biard-Piechaczyk M Benichou S 《Apoptosis : an international journal on programmed cell death》2007,12(10):1879-1892
In addition to its positive signaling function in the antigen presentation process, CD4 acts as the primary receptor for HIV-1.
Contact between CD4 and the viral envelope leads to virus entry, but can also trigger apoptosis of uninfected CD4+ T-cells through a mechanism that is poorly understood. We show that Siva-1, a death domain-containing proapoptotic protein,
associates with the cytoplasmic domain of CD4. This interaction is mediated by the cysteine-rich region found in the C-terminal
part of the Siva-1 protein. Expression of Siva-1 specifically increases the susceptibility of both T-cell lines and unstimulated
human primary CD4+ T-lymphocytes to CD4-mediated apoptosis triggered by the HIV-1 envelope, and results in activation of a caspase-dependent
mitochondrial pathway. The same susceptibility is observed in T-cells expressing a truncated form of CD4 that is able to recruit
Siva-1 but fails to associate with p56Lck, indicating that Siva-1 participates in a pathway independent of the p56Lck kinase activity. Altogether, these results suggest that Siva-1 might participate in the CD4-initiated signaling apoptotic
pathway induced by the HIV-1 envelope in T-lymphoid cells.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
954.
955.
The relationship between plasma levels of homocysteine (Hcy) and femur bone mineral density (BMD) was studied in Wistar rats.
After 8 weeks of treatment with 0.5 and 1.0 g kg−1 day−1
l-methionine the mean plasma levels of Hcy were 7.67 ± 1.25 and 61.2 ± 11.4 μmol/l, respectively. Only rats treated with the
higher dose had Hcy levels significantly higher than those of controls, 6.38 ± 0.90 μmol/l (p < 0.001). Dual Energy X-ray Absorptiometry was used to measure the BMD, which was significantly lower only in the animals
with the highest plasma levels of Hcy (p < 0.001). This led us to conclude that increased levels of Hcy are associated with risk of decreased BMD. 相似文献
956.
This paper presents a general, process-based mass balance model (CoastMab) for total phosphorus (TP) in defined coastal areas
(at the ecosystem scale). The model is based on ordinary differential equations and calculates inflow, outflow and internal
fluxes on a monthly basis. It consists of four compartments: surface water, deep water, erosion/transportation areas for fine
sediments and accumulation areas for fine sediments. The separation between surface water and deep water is not done based
on water temperature, but on sedimentological criteria instead (from the theoretical wave base). There are algorithms for
all major internal TP fluxes (sedimentation, resuspension, diffusion, mixing and burial). Validations were performed using
data from 21 different Baltic coastal areas. The results show that the model predicts monthly TP in water and chlorophyll a very well (generally within the uncertainty bands of the empirical data). The model has also been put through sensitivity
tests, which show that the most important factor regulating the predictions of the model is generally the TP concentration
in the sea beyond the coast. The model is simple to apply, since all driving variables may be accessed from maps or monitoring
programs. The driving variables include coastal area, section area (between the defined coastal area and the adjacent sea),
mean and maximum depths, latitude (used to predict water temperatures, stratification and mixing), salinity and TP concentration
in the sea. Many of the model structures are general and could be used for areas other than those included in this study,
e.g., for open coasts, estuaries or tidal coasts, as well as for other substances than phosphorus. 相似文献
957.
Ljiljana Vapa Mihajla Djan Dragana Obreht Milos Beukovic Milan Vapa 《European Journal of Wildlife Research》2007,53(1):52-54
The pheasant breeds are widely used for restocking of natural populations depleted by hunting. The pheasant population number
decline was detected during the 1970s in many hunting areas of Europe. One of its possible reasons might be the loss of adaptability
in populations originating from breeding stations, which was caused by inbreeding depression. The aim of this paper was the
analysis of genetic variability in pheasant populations from three breeding stations in Vojvodina province (Serbia) by means
of allozyme diversity detection. The allozyme variability analysis of pheasants from all three breeding stations revealed
polymorphisms at nine loci: Ldh-1, Mor-1, Mor-2, Es-1, Mod-2, Pgd, Gpi-2, Odh, and Sod. The analysis of individuals from three different breeding stations showed mean values of observed heterozygosity of H
o=0.137, polymorphism P
95%=30%, and H/P ratio H/P=0.430, which indicate a normal level of genetic variability for bird populations. Comparative analysis of three pheasant
populations showed a high level of interpopulation differentiation. 相似文献
958.
Vincent J. Tepedino Diane Gail Alston Brosi A. Bradley Trent R. Toler Terry L. Griswold 《Biodiversity and Conservation》2007,16(11):3083-3094
Capitol Reef National Park in central Utah, USA surrounds 22 managed fruit orchards started over a century ago by Mormon pioneers.
Honey bees are imported for pollination, although the area in which the Park is embedded has over 700 species of native bees,
many of which are potential orchard pollinators. We studied the visitation of native bees to apple, pear, apricot, and sweet
cherry over 2 years. Thirty species of bees visited the flowers but, except for pear flowers, most were uncommon compared
to honey bees. Evidence that honey bees prevented native bees from foraging on orchard crop flowers was equivocal: generally,
honey bee and native bee visitation rates to the flowers were not negatively correlated, nor were native bee visitation rates
positively correlated with distance of orchards from honey bee hives. Conversely, competition was tentatively suggested by
much larger numbers of honey bees than natives on the flowers of apples, apricots and cherry; and by the large increase of
native bees on pears, where honey bee numbers were low. At least one-third of the native bee species visiting the flowers
are potential pollinators, including cavity-nesting species such as Osmia lignaria propinqua, currently managed for small orchard pollination in the US, plus several fossorial species, including one rosaceous flower
specialist (Andrena milwaukiensis). We suggest that gradual withdrawal of honey bees from the Park would help conserve native bee populations without decreasing
orchard crop productivity, and would serve as a demonstration of the commercial value of native pollinators. 相似文献
959.
Parthasarathy NJ Srikumar R Manikandan S Narayanan GS Devi RS 《Cell biology and toxicology》2007,23(3):177-187
Our previous studies revealed that methanol intoxication significantly altered the non-specific immune functions in albino rats. The present investigation focuses on the effect of methanol on certain specific immune functions of cell mediated immunity such as footpad thickness, leukocyte migration inhibition test (LMI) and antibody levels. In addition, serum interleukins (IL-2, IL-4, TNF-alpha and IFN-gamma), and splenic lymphocyte subsets were measured after an immune challenge. The specific immune function tests were carried out in three different groups of albino rats, which include control, 15 and 30 days methanol intoxication. Our study reports that animal body weight, organ weight ratio, lymphoid cell counts, footpad thickness, antibody titer, IL-2, TNF-alpha, IFN-gamma, Pan T cell, CD4, macrophages, MHC class II molecule expression, and B cell counts were significantly decreased compared to control animals nevertheless, LMI, IL-4, and DNA single strand breakage were increased significantly. Plasma corticosterone level was significantly increased in the 15 days group whereas the 30 days methanol intoxication group showed considerable decrease in corticosterone level compared with control animals. Therefore, our investigation concluded that repeated exposure of methanol profoundly suppressed the cell mediated and humoral immune functions in albino rats. 相似文献
960.
Studer B Boller B Bauer E Posselt UK Widmer F Kölliker R 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(1):9-17
Crown rust, caused by Puccinia coronata f. sp. lolii, is one of the most important diseases of temperate forage grasses, such as ryegrasses (Lolium spp.), affecting yield and nutritional quality. Therefore, resistance to crown rust is a major goal in ryegrass breeding
programmes. In a two-way pseudo-testcross population consisting of 306 Lolium multiflorum individuals, multisite field evaluations as well as alternative methods based on artificial inoculation with natural inoculate
in controlled environments were used to identify QTLs controlling resistance to crown rust. Disease scores obtained from glasshouse
and leaf segment test (LST) evaluations were highly correlated with scores from a multisite field assessment (r = 0.66 and 0.79, P < 0.01, respectively) and thus confirmed suitability of these methods for crown rust investigations. Moreover, QTL mapping
based on a linkage map consisting of 368 amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers
revealed similar results across different phenotyping methods. Two major QTLs were consistently detected on linkage group
(LG) 1 and LG 2, explaining up to 56% of total phenotypic variance (V
p). Nevertheless, differences between position and magnitude of QTLs were observed among individual field locations and suggested
the existence of specific local pathogen populations. The present study not only compared QTL results among crown rust evaluation
methods and environments, but also identified molecular markers closely linked to previously undescribed QTLs for crown rust
resistance in Italian ryegrass with the potential to be applied in marker-assisted forage crop breeding.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献