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101.
Marcelo Cancela Lisboa Cohen Hermann Behling Ruben José Lara Clarisse Beltrão Smith Hellen Rosy Soares Matos Vincent Vedel 《Vegetation History and Archaeobotany》2009,18(6):425-439
Wetland dynamics in northern Brazil during the Holocene were studied by pollen analysis and AMS radiocarbon dating of three
cores. Near the Amazon mouth region, covered mainly by primary Amazon coastal forest and herbaceous vegetation, the pollen
record indicates the dominance of mangroves between 4800 and 1100 cal yr b.p. A contraction of the mangrove area and an expansion of herbaceous and fern vegetation occurred between 1100 and 750 cal yr
b.p. The period between 750 and 200 cal yr b.p. is characterized by an expansion of mangrove and a decrease in herbaceous and fern vegetation. This trend continued until
the present. On Atalaia Island, the sediment core indicates a period with poor pollen preservation between 830 and 630 cal yr
b.p. Between 630 and 330 cal yr b.p., mangroves expanded. Later, up to 45 cal yr b.p., the mangrove area decreased and the herbaceous vegetation expanded. During the last hundred years, the relative sea-level
rise most probably favored the mangrove expansion as far as the topographically highest sector on this island, while the herbaceous
vegetation decreased. The pollen data from água Preta Lake indicate dry conditions, as reflected by the poor pollen preservation
between 390 and 240 cal yr b.p. Between 240 and 60 cal yr b.p., restinga and Amazon coastal forest with palms dominated this region. For the last 120 years, the record indicates an expansion
of the mangrove area. However, recent confinement of mangrove development to the topographically highest area, and the loss
of mangrove areas on the lowest surfaces have led to a net loss of mangrove coverage during the last decades. 相似文献
102.
Florian Wittmann Bianca Thaís Zorzi Fernando Augusto Tambelini Tizianel Marcus Vinicius Santiago Urquiza Rogério Rodrigues Faria Nathália Machado e Sousa Érica de Souza Módena Roberto Macedo Gamarra Augusto Lisboa Martins Rosa 《Folia Geobotanica》2008,43(4):397-411
The aboveground wood biomass (AWB) of tropical forests plays an important role in the global carbon cycle, and local AWB estimates provide essential data that enable the extrapolation of biomass stocks to ecosystem or biome-wide carbon cycle modelling. Few AWB estimates exist in Neotropical freshwater floodplains, where tree species distribution and forest structure depend on the height and duration of periodic inundations. We investigated tree species composition, forest structure, wood specific gravity, and AWB of trees ≥10 cm dbh in 16 plots totalling an area of 1 ha in a seasonally inundated riparian forest of the lower Miranda River, southern Pantanal, Brazil. The 443 tree individuals belonged to 46 species. Four species (Inga vera, Ocotea suaveolens, Tabebuia heptaphylla and Cecropia pachystachya) comprised more than 50% of the Total Importance Values (TIV), and floristic similarities between the plots averaged 38%. Although we detected an overall increase in species diversity correlated with decreasing flood levels, the most important tree species had almost identical distribution patterns along the flooding gradient. The stand basal area per plot (±?s.d.) amounted to 3.0?±?1.1 m2 (47.8?±?18.1 m2/ha), and the tree heights averaged 10.9?±?1.4 m. Multiplying the individual basal areas by individual tree heights and a form factor of 0.6, we estimated the aboveground wood volume (AWV) for each individual, and for each plot (24.4?±?11.7 m3, 391.1?±?188 m3/ha). Wood specific gravity (SG) varied between 0.39 g/cm3 (Cecropia pachystachya) and 0.87 g/cm3 (Tabebuia heptaphylla), with a stand level average of 0.63?±?0.12 g/cm3. Multiplying the individual AWV with species SG, we estimated the plot AWB to be 16.2?±?6.4 Mg (259.4?±?102 Mg/ha). This value is comparable to that reported for late-successional forest stands of Amazonian floodplain forests, and it is close to the worldwide tropical average AWB. Because tree heights in the present forest were comparatively low when compared to other Neotropical forests, we found that resprouting of stems accounted for comparatively high basal areas. We argue that stem resprouting is an adaptation of tree species originating in non-flooded Cerrado to the seasonal inundations of riparian forests. 相似文献
103.
104.
Borzone G Liberona L Olmos P Sáez C Meneses M Reyes T Moreno R Lisboa C 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,293(3):R1342-R1349
Syrian Golden hamsters develop severe emphysema after a single intratracheal dose of elastase, whereas Sprague-Dawley rats exhibit mild emphysema with the same dose per kilogram body weight. We hypothesized that the development of severe emphysema is prevented in rats by the high serum level of alpha1-antitrypsin reported in rats, compared with hamsters, which provides for a high lung elastase inhibitory capacity (EIC). To explore this possibility, we challenged the antiprotease system of the rats by treating them with three similar weekly doses of elastase. Four months after treatment, we evaluated changes in histology, volume, and elastic properties of rat lungs and compared them with those of hamsters receiving a single dose of elastase. We also measured serum alpha1-antitrypsin levels and serum and lung EIC in control rats and hamsters. Results showed that, in association with 40% less serum and lung EIC compared with rats (P < 0.001), hamster lungs had upper-lobe bullae formation, severe microscopic emphysema, a fourfold increase in lung volume (P < 0.01) and a threefold increase in constant k, an index of compliance, of the lung deflation pressure-volume curve (P < 0.01). In contrast, rats developed mild emphysema, with only 50% increase in volume (P < 0.05) and 60% increase in constant k (P < 0.01). In conclusion, two species that differ in serum and lung EIC exhibit significant differences in emphysema development after elastase. Rats with high EIC, despite receiving three doses of elastase, showed significantly less derangement of morphological and physiological parameters than hamsters with low EIC receiving a single dose. 相似文献
105.
de Oliveira E Teixeira Silva Fagundes A Teixeira Bonomo I Curty FH Fonseca Passos MC de Moura EG Lisboa PC 《Life sciences》2007,81(15):1241-1246
Leptin has stimulatory effects on the hypothalamic-pituitary-thyroid axis and on deiodinases activities. Here, we evaluated the effect of leptin injection upon in vivo and in vitro thyroid 125I uptake (RAIU). We designed two experiments: acute leptin (LepA) with a single dose of leptin (8 microg/100 g BW/sc), and chronic leptin (LepC), injected with the same dose of LepA, once a day, for 6 days. In parallel, control groups were saline-injected. For in vivo study, part of the animals were injected with 125I (3700 Bq) and killed after 15 or 120 min. In vivo thyroid RAIU was not changed in LepA animals. However, LepC animals showed higher in vivo thyroid RAIU (15 min:+130% and 120 min:+72%; p<0.05). For in vitro study, the other animals were killed and their thyroids were incubated with 125I. Thyroids explants from LepA and LepC groups presented lower thyroid 125I content (-32% and -29% p<0.05, respectively). The amount of our data suggest that, in vitro, leptin causes a direct inhibition of the rat thyroid RAIU, but in vivo, the effect of leptin was different according to the treatment period, which indicates that other indirect mechanisms are involved in the in vivo leptin chronic stimulation of the thyroid gland. 相似文献
106.
Recently, we showed that both maternal malnutrition during lactation and leptin treatment during the neonatal period program thyroid function. In this study we evaluate whether maternal leptin treatment during lactation programs thyroid function of the offspring in the adulthood. The dams were divided into 2 groups: Lep-daily sc single injected with 8 microg/100 g of body weight with recombinant rat leptin during the last 3 days of lactation and control group (C) that received the same volume of saline. The 180 day-old animals received a single i.p. injection of (125)I (2.22x10(4) Bq) and they were killed 2 h after the injection. Triiodothyronine (T3), thyroxine (T4), thyrotropin (TSH) and leptin concentrations were measured by radioimmunoassay. The milk of leptin-treated mothers on the last day of treatment had higher leptin (p<0.05) concentration. The pups of the leptin-treated mothers had at 21 days an unchanged T3, T4 and leptin serum concentrations with higher TSH (p<0.05). The offspring of Lep mothers had at 180 days a higher T3 (p<0.05) with normal thyroid (125)I uptake, T4 and TSH serum concentrations compared to the controls. So, the mother's hyperleptinaemia during lactation programs to a higher T3 serum concentration on the offspring, probably by a higher leptin transfer through the milk. 相似文献
107.
Cristiane Varella Lisboa Rafael Veríssimo Monteiro Andreia Fonseca Martins Samantha Cristina das Chagas Xavier Valdirene dos Santos Lima Ana Maria Jansen 《Memórias do Instituto Oswaldo Cruz》2015,110(3):394-402
Here, we present a review of the dataset resulting from the 11-years follow-up of
Trypanosoma cruzi infection in free-ranging populations of
Leontopithecus rosalia (golden lion tamarin) and
Leontopithecus chrysomelas (golden-headed lion tamarin) from
distinct forest fragments in Atlantic Coastal Rainforest. Additionally, we present
new data regarding T. cruzi infection of small mammals (rodents and
marsupials) that live in the same areas as golden lion tamarins and characterisation
at discrete typing unit (DTU) level of 77 of these isolates. DTU TcII was found to
exclusively infect primates, while TcI infected Didelphis aurita and
lion tamarins. The majority of T. cruzi isolates derived from
L. rosalia were shown to be TcII (33 out 42) Nine T.
cruzi isolates displayed a TcI profile. Golden-headed lion tamarins
demonstrated to be excellent reservoirs of TcII, as 24 of 26 T.
cruzi isolates exhibited the TcII profile. We concluded the following:
(i) the transmission cycle of T. cruzi in a same host species and
forest fragment is modified over time, (ii) the infectivity competence of the golden
lion tamarin population fluctuates in waves that peak every other year and (iii) both
golden and golden-headed lion tamarins are able to maintain long-lasting infections
by TcII and TcI. 相似文献
108.
Immobilization of Candida rugosa lipase onto an eco-friendly support in the presence of ionic liquid
109.
Micheline Cristiane Rocha de Souza Cybelle Teixeira Marques Celina Maria Guerra Dore Fernando Roberto Ferreira da Silva Hugo Alexandre Oliveira Rocha Edda Lisboa Leite 《Journal of applied phycology》2007,19(2):153-160
The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans,
which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC50 (the half maximal inhibitory concentration) of 0.058 mg·mL−1, while the IC50 for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg·mL−1, respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation
tests showed that fucoidan had an IC50 of 1.250 mg·mL−1 and that the kappa, iota and lambda carrageenans had an IC50 of 2.753 and 2.338 and 0.323 mg·mL−1, respectively. Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial
effect of algal polysaccharides as antioxidants. 相似文献
110.
P. P. Tonini C. G. S. Lisboa C. O. Silva S. C. Mazzoni-Viveiros M. S. Buckeridge 《Trees - Structure and Function》2007,21(1):13-21
Seeds of Sesbania virgata (Cav.) Pers. (Leguminosae) contain galactomannan as a cell wall storage polysaccharide in the endosperm. After germination,
it is hydrolysed by three enzymes: α-galactosidase (EC 3.2.1.22), endo-β-mannanase (EC 3.2.1.78) and β-mannosidase (EC 3.2.1.25).
This work aimed at studying the role of the testa (seed coat) on galactomannan degradation during and after germination. Seeds
were imbibed in water, with and without the testa, and used to evaluate the effect of this tissue on storage mobilisation,
as well as its possible role in the galactomannan hydrolases activities. Immunocytochemistry and immunodotblots were used
to follow biochemical events by detecting and localising endo-β-mannanase in different tissues of the seed. Endo-β-mannanase
and α-galactosidase activities were found in the testa and latter in the endosperm during galactomannan degradation. The former
enzyme was immunologically detected in the testa, mainly during germination. The absence of the testa during imbibition led
to the anticipation of protein mobilisation and increased of the α-galactosidase activity and galactomannan degradation. Thus,
the testa appears to play a role during storage mobilisation in the legume seed of S. virgata probably by participating in the control of the production, modification and/or storage of the hydrolases. 相似文献