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41.
Above- and belowground organic matter storage and production in a tropical pine plantation and a paired broadleaf secondary forest 总被引:7,自引:1,他引:6
The distribution of tree biomass and the allocation of organic matter production were measured in an 11-yr-old Pinus caribaea plantation and a paired broadleaf secondary forest growing under the same climatic conditions. The pine plantation had significantly
more mass aboveground than the secondary forest (94.9 vs 35.6 t ha-1 for biomass and 10.5 vs 5.0 t ha-1 for litter), whereas the secondary forest had significantly more fine roots (⩽2 mm diameter) than the pine plantation (10.5 and 1.0
t ha-1, respectively). Standing stock of dead fine roots was higher than aboveground litter in the secondary forest. In contrast,
aboveground litter in pine was more than ten times higher than the dead root fraction. Both pine and secondary forests had
similar total organic matter productions (19.2 and 19.4 t ha-1 yr-1, respectively) but structural allocation of that production was significantly different between the two forests; 44% of total
production was allocated belowground in the secondary forest, whereas 94% was allocated aboveground in pine. The growth strategies
represented by fast growth and large structural allocation aboveground, as for pine, and almost half the production allocated
belowground, as for the secondary forest, illustrate equally successful, but contrasting growth strategies under the same
climate, regardless of soil characteristics. The patterns of accumulation of organic matter in the soil profile indicated
contrasting nutrient immobilization and mineralization sites and sources for soil organic matter formation. 相似文献
42.
Delia Ines Lugo Shu-Cheng Chen Alan K. Hall Reza Ziai James L. Hempstead James I. Morgan 《Journal of neurochemistry》1991,56(2):457-461
HPLC analysis of guanidinium hydrochloride extracts of neonatal and adult rat brain revealed a polypeptide that is present in high concentration in the immature nervous system, but whose levels decline dramatically in the adult. This polypeptide has been isolated and its complete amino acid sequence determined by gas-phase Edman degradation following specific chemical and enzymatic cleavages. The molecule is identified as thymosin beta 10, a member of a multigene family that encodes a structurally conserved series of small acidic polypeptides of uncertain function. Thymosin beta 10 is present in the developing nervous system as early as embryonic day 9. Levels subsequently increase to peak values between embryonic day 15 and postpartum day 3, before falling to adult values (about a 20-fold reduction) by postpartum day 14. The elevated levels of thymosin beta 10 in fetal and neonatal brain correlate with high levels of thymosin beta 10 mRNA, whereas the low values of the polypeptide in the adult and juvenile are mirrored by an approximate 15-fold reduction in specific mRNA. In comparison, the levels of thymosin beta 4 polypeptide, a homologue of thymosin beta 10, only decline by about 20% during the same developmental period. However, the mRNA encoding thymosin beta 4 is elevated in fetal brain, and its levels decrease approximately four-fold to a stable value around the time of birth. The reason for this discrepancy between thymosin beta 4 protein and mRNA levels is unknown. Thymosin beta 10 can also be detected by HPLC in fetal liver, where levels are approximately 5% of those in brain. In liver, thymosin beta 10 also declines following birth. It is concluded that beta-thymosin expression (as measured by steady-state mRNA and polypeptide levels) is both up- and down-regulated during different phases of maturation of the mammalian nervous system. 相似文献
43.
Seal J Lamotte Y Donche F Bouillot A Mirguet O Gellibert F Nicodeme E Krysa G Kirilovsky J Beinke S McCleary S Rioja I Bamborough P Chung CW Gordon L Lewis T Walker AL Cutler L Lugo D Wilson DM Witherington J Lee K Prinjha RK 《Bioorganic & medicinal chemistry letters》2012,22(8):2968-2972
A novel series of quinoline isoxazole BET family bromodomain inhibitors are discussed. Crystallography is used to illustrate binding modes and rationalize their SAR. One member, I-BET151 (GSK1210151A), shows good oral bioavailability in both the rat and minipig as well as demonstrating efficient suppression of bacterial induced inflammation and sepsis in a murine in vivo endotoxaemia model. 相似文献
44.
45.
Miriam Bellido Laura Lugo Jorge A Roman-Blas Santos Castañeda Jose R Caeiro Sonia Dapia Emilio Calvo Raquel Largo Gabriel Herrero-Beaumont 《Arthritis research & therapy》2010,12(4):R152-11
Introduction
Osteoporosis (OP) increases cartilage damage in a combined rabbit model of OP and osteoarthritis (OA). Accordingly, we assessed whether microstructure impairment at subchondral bone aggravates cartilage damage in this experimental model. 相似文献46.
Juana Maria Lugo Aymé Oliva Antonio Morales Osvaldo Reyes Hilda Elisa Garay Fidel Herrera Ania Cabrales Ever Pérez Mario Pablo Estrada 《Journal of peptide science》2010,16(11):633-643
To date, many technologies have been developed to increase efficiency in aquaculture, but very few successful biotechnology molecules have arrived on the market. In this context, marine biotechnology has an opportunity to develop products to improve the output of fish in aquaculture. Published in vivo studies on the action of the pituitary adenylate cyclase‐activating polypeptide (PACAP) in fish are scarce. Recently, our group, for the first time, demonstrated the biological role of this neuropeptide administrated by immersion baths in the growth and development of larval fish. In this work, we have evaluated the effects of recombinant Clarias gariepinus PACAP administration by intraperitoneal injection on growth performance and feeding behavior in juvenile fish. Our results showed the physiological role of this peptide for growth control in fish, including the juvenile stage, and confirm that its biological functions are well conserved in fish, since C. gariepinus PACAP stimulated growth in juvenile tilapia Oreochromis niloticus. In addition, we have observed that the growth‐promoting effect of PACAP in juvenile tilapia was correlated with higher GH concentration in serum. With regard to the neuroendocrine regulation of growth control by PACAP, it was demonstrated that PACAP stimulates food intake in juvenile tilapia. In general, PACAP appears to act in the regulation of the growth control in juvenile fish. These findings propose that PACAP is a prominent target with the potential to stimulate fish growth in aquaculture. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
47.
The crustacean hyperglycemic hormone (CHH) plays an important role in the regulation of hemolymph glucose levels, but it is also involved in other functions such as growth, molting and reproduction. In the present study we describe the first CHH family gene isolated from the Atlantic Ocean shrimp Litopenaeus schmitti. Sequence analysis of the amplified cDNA fragment revealed a high nucleotide sequence identity with other CHHs. Northern blot analysis showed that the isolated CHH mRNA from L. schmitti is present in the eyestalk but not in muscle or stomach. We also investigated the ability of dsRNA to inhibit the CHH function in shrimps in vivo. Injection of CHH dsRNA into the abdominal hemolymph sinuses resulted in undetectable CHH mRNA levels within 24 h and a corresponding decrease in hemolymph glucose levels, suggesting that functional gene silencing had occurred. These findings are the first evidence that dsRNA technique is operative in adult shrimps in vivo. 相似文献
48.
Opinion This is a series of contributions, expressing explicit opinions with regard to contemporary topics in limnology. These Opinions are mostly based on new books with a large impact, but can also refer to other currently debated topics. Documented reactions to these contributions should be sent to the editor-in-chief; they will be considered for publication in subsequent issues. 相似文献
49.
Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands 总被引:2,自引:2,他引:0
Britten CJ; van den Eijnden DH; McDowell W; Kelly VA; Witham SJ; Edbrooke MR; Bird MI; de Vries T; Smithers N 《Glycobiology》1998,8(4):321-327
The alpha3 fucosyltransferase, FucT-VII, is one of the key
glycosyltransferases involved in the biosynthesis of the sialyl Lewis X
(sLex) antigen on human leukocytes. The sialyl Lewis X antigen
(NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential
component of the recruitment of leukocytes to sites of inflammation,
mediating the primary interaction between circulating leukocytes and
activated endothelium. In order to characterize the enzymatic properties of
the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been
expressed in Trichoplusia ni insect cells. The enzyme is capable of
synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from
3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels
of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies
using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors
demonstrate that FucT-VII is able to synthesize both di-fucosylated and
tri-fucosylated structures from mono- fucosylated precursors, but
preferentially fucosylates the distal GlcNAc within a polylactosamine
chain. Furthermore, the rate of fucosylation of the internal GlcNAc
residues is reduced once fucose has been added to the distal GlcNAc. These
results indicate that FucT-VII is capable of generating complex selectin
ligands, in vitro , however the order of fucose addition to the lactosamine
chain affects the rate of selectin ligand synthesis.
相似文献
50.
The forests of the Luquillo Experimental Forest Long-Term Ecological Research site are subject to low-intensity, widespread
disturbance that establishes levels of background mortality that contrast with periodic catastrophic mortality resulting from
hurricanes and landslides. Although catastrophic mortality is more dramatic, background mortality is still more important
in determining population turnover. However, catastrophic mortality may still be an important agent in determining ecosystem
structure. Catastrophic disturbances affect forest function in many ways besides mortality, some of which are only apparent
in the context of long-term studies. Since most ecosystems are subject to some form of catastrophic disturbance, general principles
can be derived from comparative studies of disturbance in different systems. 相似文献