Influences of aging and caloric restriction on the transcriptional profile of skeletal muscle from rhesus monkeys

In laboratory rodents, caloric restriction (CR) retards several age-dependent physiological and biochemical changes in skeletal muscle, including increased steady-state levels of oxidative damage to lipids, DNA, and proteins. We have previously used high-density oligonucleotide arrays to show that CR can prevent or delay most of the major age-related transcriptional alterations in the gastrocnemius muscle of C57BL/6 mice. Here we report the effects of aging and adult-onset CR on the gene expression profile of 7,070 genes in the vastus lateralis muscle from rhesus monkeys. Gene expression analysis of aged rhesus monkeys (mean age of 26 years) was compared with that of young animals (mean age of 8 years). Aging resulted in a selective up-regulation of transcripts involved in inflammation and oxidative stress, and a down-regulation of genes involved in mitochondrial electron transport and oxidative phosphorylation. Middle-aged monkeys (mean age of 20 years) subjected to CR since early adulthood (mean age of 11 years) were studied to determine the gene expression profile induced by CR. CR resulted in an up-regulation of cytoskeletal protein-encoding genes, and also a decrease in the expression of genes involved in mitochondrial bioenergetics. Surprisingly, we did not observe any evidence for an inhibitory effect of adult-onset CR on age-related changes in gene expression. These results indicate that the induction of an oxidative stress-induced transcriptional response may be a common feature of aging in skeletal muscle of rodents and primates, but the extent to which CR modifies these responses may be species-specific.

O efeito de diferentes volumes de treinamento de força nas adaptações funcionais e morfológicas da musculatura esquelética em indivíduos treinados

O objetivo desse estudo foi verificar o efeito de diferentes volumes de treinamento de força na força máxima de membros inferiores e na hipertrofia do reto femoral e do vasto lateral após quatro, oito e doze semanas em indivíduos treinados em força. Vinte e seis indivíduos jovens saudáveis do sexo masculino (idade 23,6 ± 4,6 anos, massa corporal 76,6 ± 7,5 kg, estatura 1,75 ± 0,1 cm), com tempo médio de treinamento de força (4,7 ± 4,1 anos) foram divididos em três grupos experimentais, treinamento de força alto volume (TFAV, n = 8), treinamento de força médio volume (TFMV, n = 9) e treinamento de força baixo volume (TFBV, n = 9). As medidas de força dinâmica máxima (1RM) e de área de secção transversa muscular (ASTM) do reto femoral (RF) e do vasto lateral (VL) foram realizadas nos momentos pré- treinamento, pós quatro semanas, pós oito semanas e pós-treinamento. O volume total de treinamento apresentou aumento estatístico para todos os grupos TFAV (p < 0,0001), TFMV (p < 0,0001) e TFBV (p < 0,0001) ao longo do período experimental. Os valores de 1RM aumentaram de maneira significativa após a oitava semana de treinamento TFAV (11,8 ± 4,7%; p < 0,0001) e TFMV (12,1 ± 8,5%; p < 0,0001) e TFBV (9,6 ± 7,3%; p < 0,001) e no pós-treinamento TFAV (13,9 ± 3,9%; p < 0,0001), TFMV (16,7 ± 10,8%; p < 0,0001) e TFBV (14,0 ± 8,1%; p < 0,0001) para todos os grupos, porém não foi observado diferença entre os grupos. A ASTM do RF apresentou aumento estatístico no pós-treinamento somente para o grupo TFAV (15,0 ± 11,9%; p < 0,0001). Apenas o grupo TFAV aumentou estatisticamente a ASTM do VL após quatro semanas de treinamento (7,71 ± 4,42%; p < 0,0001), porém todos os grupos aumentaram significativamente a ASTM do VL após oito semanas de treinamento TFAV (11,37 ± 3,88%; p < 0,0001), TFMV (9,68 ± 9,36%; p < 0,0001) e TFBV (7,26 ± 3,15%; p < 0,01) e no pós-treinamento TFAV (14,54 ± 4,07%; p < 0,0001), TFMV (14,77 ± 8,24%; p < 0,0001) e TFBV (8,66 ± 3,97%; p < 0,001), porém não foi observado diferença entre os grupos. Os resultados do presente estudo demonstraram que, independente do volume adotado, os ganhos de força máxima foram semelhantes. Por outro lado, a ASTM foi influenciada pelo volume de treinamento, dado que o grupo TFAV foi o único que apresentou aumento significativo da ASTM do RF no pós-treinamento e aumentou a ASTM do VL com apenas quatro semanas de treinamento

Efeito de diferentes intensidades do treinamento de força nos ganhos de força máxima e hipertrofia muscular

O presente estudo investigou o efeito de diferentes intensidades do treinamento de força (TF), aplicadas com volume total de treino (VTT) equalizado, nos ganhos de força dinâmica máxima (1RM) e massa muscular dos membros superiores e inferiores. Trinta voluntários do sexo masculino, com idade entre 18 e 30 anos, participaram de 12 semanas de TF com uma frequência semanal de duas sessões. Foi utilizado um protocolo de treinamento unilateral com um dos lados do corpo realizando o exercício com intensidade equivalente a 20% 1RM (G20) e o lado contralateral utilizando uma das três intensidades 40%, 60% ou 80% 1RM (G40, G60 e G80, respectivamente). O grupo G20 realizava três séries compostas de repetições até a falha concêntrica e o VTT era calculado e replicado para os demais grupos. A força dinâmica máxima e a área de secção transversa (AST) dos músculos flexores do cotovelo e do vasto lateral foram avaliadas nos momentos pré, 6 semanas e pós-treinamento. Os resultados demonstraram que os grupos G40, G60 e G80 apresentaram ganhos similares de AST (25%, 25,1% e 25%, flexores do cotovelo e 20,5%, 20,4% e 19,5% vasto lateral, respectivamente, p<0,05). Somente o grupo G80 demonstrou diferença significante com o grupo G20 na comparação do período pós-treinamento (25% e 14,4%, respectivamente para os flexores do cotovelo e 19,5% e 7,9%, respectivamente para vasto lateral, p<0,05). Para os ganhos de 1RM o grupo G80 demonstrou maiores aumentos após 12 semanas de TF para a flexão unilateral do cotovelo na posição em pé (54,2% p<0,05) e para o leg press 45º os grupos G60 e G80 demonstraram os maiores aumentos (55,4% e 45,7%, respectivamente, p<0,05). Assim, quando o VTT foi equalizado entre diferentes intensidades (40, 60 e 80% 1RM) os ganhos da AST tanto dos flexores do cotovelo quanto o vasto lateral foram semelhantes e a intensidade de 20% 1RM não causou aumento significante da AST. No que diz respeito a força muscular as intensidades mais elevadas (60% e 80% 1RM) foram superiores em promover ganhos de força do que as demais intensidades utilizadas. Esses dados sugerem que ao equalizar o VTT os ganhos de massa muscular são semelhantes para as intensidades de treinamento entre 40- 80% 1RM. Além disso, a intensidade de 20% 1RM, mesmo com o VTT equalizado com as intensidades maiores, não promove aumentos de massa muscular para ambos os segmentos corporais. Por outro lado, intensidades altas de treinamento produzem os maiores ganhos de força máxima em membros superiores e inferiores

Benthic foraminiferal fauna in the Ionian Sea

To reconstruct paleoceanographic changes in the eastern Mediterranean during the last 330,000 years, we studied benthic foraminifera in a piston core from the Ionian Sea. The fauna exhibits large fluctuations in foraminiferal number, diversity, and species composition. Interglacials are characterized by low foraminiferal number and diversity indicating oligotrophic conditions. Directly below or above interglacial sapropels, increased numbers of low-oxygen-tolerant species indicate a strong reduction of deep water circulation. Glacials are characterized by increased foraminiferal number and diversity and faunas that are dominated by shallow infaunal species indicating mesotrophic conditions. Around glacial sapropel S6 very high foraminiferal numbers and the dominance of shallow and deep infaunal species suggest enhanced organic matter fluxes. These faunal results provide information about changes in the African and North Atlantic climate systems (monsoon and westerlies) controlling the humidity and wind stress in the Mediterranean region.

Middle Miocene isotope stratigraphy and paleoceanographic evolution of the northwest and southwest Australian margins (Wombat Plateau and Great Australian Bight)

The benthic stable isotope record from ODP Site 761 (Wombat Plateau, NW Australia, 2179.3 m water depth) documents complete recovery of the middle Miocene delta13C excursion corresponding to the climatic optimum and subsequent expansion of the East Antarctic Ice Sheet. The six main delta13C maxima of the "Monterey Excursion" between 16.4 and 13.6 Ma and the characteristic stepped increase in delta18O between 14.5 and 13.9 Ma are clearly identified. The sedimentary record of the shallower ODP Sites 1126 and 1134 [Great Australian Bight (GAB), SWAustralia, 783.8 and 701 m water depth, respectively] is truncated by several unconformities. However, a composite benthic stable isotope curve for these sites provides a first middle Miocene bathyal record for southwest Australia. The delta18O and delta13C curves for Sites 1126 and 1134 indicate a cooler, better-ventilated water mass at ~700 m water depth in the Great Australian Bight since approximately 16 Ma. This cooler and younger water mass probably originated from a close southern source. Cooling of the bottom water at ~16 Ma started much earlier than at other sites of equivalent paleodepths in the central and western parts of the Indian Ocean. At Site 761, the delta18O curve shows an excellent match with the global sea level curve between ~11.5 and 15.1 Ma, and thus closely reflects changes in global ice volume. Prior to 15.1 Ma, the mismatch between the delta18O curve and the sea level curve indicates that delta18O fluctuations are mainly due to changes in bottom water temperature.

Benthic foraminiferal assemblages and epifaunal isotope record of the Agulhas Plateau

Benthic foraminiferal assemblages and the carbon isotope composition of the epifaunal benthic foraminifera Epistominella exigua and Fontbotia wuellerstorfi have been investigated along core MD02-2589 located at the southern Agulhas Plateau (41°26.03'S, 25°15.30'E, 2660 m water depth). This study aims to evaluate changes in the benthic paleoenvironment and its influence on benthic d13C with a notable focus on E. exigua, a species associated with phytodetritus deposits and poorly studied in isotope paleoceanographic reconstructions. The benthic foraminiferal assemblages (>63 µm) show large fluctuations in species composition suggesting significant changes in the pattern of ocean surface productivity conceivably related to migrations of the Subtropical Convergence (STC) and Subantarctic Front (SAF). Low to moderate seasonality and relatively higher food supply to the seafloor are indicated during glacial marine isotope stages (MIS) 6, 4, and 2 and during MIS 3, probably associated with the northward migration of the SAF and confluence with the more stationary STC above the southern flank of the Agulhas Plateau. The lowest organic carbon supply to the seafloor is indicated from late MIS 5b to MIS 4 as a consequence of increased influence of the Agulhas Front (AF) and/or weakening of the influence of the STC over the region. Episodic delivery of fresh organic matter, similar to modern conditions at the core location, is indicated during MIS 5c-MIS 5e and at Termination I. Comparison of this paleoenvironmental information with the paired d13C records of E. exigua and F. wuellerstorfi suggests that organic carbon offsets d13C of E. exigua from ambient bottom water d13CDIC, while its d13C amplitude, on glacial-interglacial timescales, does not seem affected by changes of organic carbon supply to the seafloor. This suggests that this species calcifies preferentially during the short time span of the year when productivity peaks and phytodetritus is delivered to the seafloor. Therefore E. exigua, while offset from d13CDIC, potentially more faithfully records the amplitude of ambient bottom water d13CDIC changes than F. wuellerstorfi, notably in settings such as the Southern Ocean that experienced substantial changes through time in the organic carbon supply to the seafloor.

Absolute abundances of benthic foraminifers and stable isotopes from the Alvin dives 3709-3712

The presence of gas hydrates on the Blake Ridge diapir, northeastern Atlantic Ocean, offers an opportunity to study the impact of methane seepage on the ecology and geochemistry of benthic foraminifera in the late Holocene. Three push cores, covering a time span of ~ 1000 yrs, were retrieved from three distinct microhabitats at the top of the diapir at a water depth of ~ 2150 m: (i) sediments away from seepage (control core), (ii) sediments overlain by clusters of methanotrophic and thiotrophic bivalves, and (iii) chemoautotrophic microbial mats. The foraminiferal assemblages at the two seep sites are marked by a reduction in benthic foraminiferal species diversity, coupled with a near-absence of agglutinated species. However, an opportunistic population rise in CH4- or H2S-tolerant calcareous species (e.g., Globocassidulina subglobosa and Cassidulina laevigata) that utilize the abundant trophic resources at the seeps has led to an increase in the overall assemblage density there. The delta18O and delta13C values of three species of benthic foraminifera - Gyroidinoides laevigatus, Globocassidulina subglobosa, and Uvigerina peregrina - and the planktonic species Globorotalia menardii were acquired from all three cores. The benthic species from methane seeps yield delta13C values of 0.1 to - 4.2 (per mil VPDB), that are distinctly more 13C-depleted relative to the delta13C of 0.4 to - 1.0 (per mil VPDB) at the control (off seep) site. The species from a mussel-bed site exhibit more negative delta13C values than those from microbial mats, possibly reflecting different food sources and higher rate of anaerobic oxidation of methane. The positive delta13C values in the paired planktonic species suggest that authigenic carbonate precipitation did not overprint the observed 13C depletions. Hence the probable cause of negative delta13C of benthic foraminifera is primary calcification from Dissolved Inorganic Carbon (DIC) containing mixed carbon fractions from (a) highly 13C-depleted, microbially-oxidized methane and (b) a seawater source.

Large size in an island-dwelling bird: intraspecific competition and the Dominance Hypothesis

Differences between island- and mainland-dwelling forms provide several classic ecological puzzles. Why, for instance, are island-dwelling passerine birds consistently larger than their mainland counterparts? We examine the 'Dominance hypothesis', based on intraspecific competition, which states that large size in island passerines evolves through selection for success in agonistic encounters. We use the Heron Island population of Capricorn silvereyes (Zosterops lateralis chlorocephalus), a large-bodied island-dwelling race of white-eye (Zosteropidae), to test three assumptions of this hypothesis; that (i) large size is positively associated with high fitness, (ii) large size is associated with dominance, and (iii) the relationship between size and dominance is particularly pronounced under extreme intraspecific competition. Our results supported the first two of these assumptions, but provided mixed evidence on the third. On balance, we suggest that the Dominance Hypothesis is a plausible mechanism for the evolution of large size of island passerines, but urge further empirical tests on the role of intraspecific competition on oceanic islands versus that on mainlands.