Regional variability in landscape effects on forest bird communities

Landscape Ecology - Functional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique...     

Patch isolation only matters for specialist butterflies but patch area affects both specialist and generalist species

Over the past four decades, many researchers have applied the theory of island biogeography (IBT) to predict and understand species loss and distribution in fragmented landscapes. Recent studies found that specialist species were more affected by fragment size and isolation than generalists. However, the mechanisms underlying different effects of area and isolation among specialists and generalists are unknown. We tested the predictions of IBT on butterfly assemblages in Tokyo, Japan, and hypothesized that the effects of fragment size and isolation would be stronger for specialists than for generalists. We classified butterfly species into specialists and generalists for each of two dimensions (food range and voltinism) and according to tolerance to the matrix. We recorded 26 feeding specialists and 27 generalists, 24 seasonal specialists and 29 generalists, 32 low matrix-tolerant species and 21 high matrix-tolerant species in 20 forest fragments. We used generalized linear models to relate the number of species in a fragment to fragment size and isolation (distance to the mainland). The averaged models based on AICc showed that fragment size had positive and significant effects on both specialist and generalist and high matrix-tolerant butterfly species richness. However, the negative effects of isolation on species richness were only found in specialist and low matrix-tolerant species. Our results demonstrate that patch isolation only affects specialist species. This suggests that when applying IBT to terrestrial fragmented landscapes, researchers should be careful not to overlook patch area and isolation effects on specialists.     

Multiple high-throughput analyses monitor the response of E. coli to perturbations

Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of Escherichia coli cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast, E. coli actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate. E. coli thus seems to use complementary strategies that result in a metabolic network robust against perturbations.     

Changes in the charged metabolite and sugar profiles of pasteurized and unpasteurized Japanese sake with storage

Japanese sake (rice wine) is commonly heat treated (pasteurized) to maintain its quality. In this study, temporal changes in the metabolite profiles of pasteurized and unpasteurized sake were investigated during storage. Metabolomic analyses were conducted for eight sets of pasteurized and unpasteurized sake obtained from single process batches stored at 8 or 20 °C for 0, 1, 2, or 4 months. Capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography tandem mass spectrometry were used to obtain charged metabolite and sugar profiles, respectively. The total amino acid concentration decreased with storage, and the decrease was faster in pasteurized sake than in unpasteurized. The organic acid concentrations were relatively constant in both types of sake. Peptide and glucose concentrations increased and polysaccharide concentrations decreased in unpasteurized sake, while they were relatively constant in pasteurized sake. Rather than stabilizing the sake metabolite profile during storage, pasteurization results in characteristic changes compared to unpasteurized sake.     

Stimulation of gamma-aminobutyric acid production in vine-ripe tomato (Lycopersicon esculentum Mill.) fruits under modified atmospheres

Stimulation of gamma-aminobutyric acid (GABA) production under low O2 and high CO2 conditions (adjusted aerobic atmosphere) under which ethanol fermentation could be avoided was studied. Vine-ripe tomato fruits were stored under hypoxia conditions and adjusted aerobic atmospheres as well as in the air at 15 degrees C for 13 days and at 30 degrees C for 6 days. At 30 degrees C tomato fruit GABA concentration under the adjusted aerobic atmosphere (O2 11%, CO2 9%) was significantly higher by 48% than that in air after 6 days from the start of storage. Increased accumulation of alanine under the adjusted aerobic atmosphere supports the observation that this atmosphere stimulates GABA production. The results demonstrate that the concentration of GABA as a beneficial substance for antihypertensive effects and so on can be increased by storing tomato fruits under adjusted aerobic atmospheres for the first time.     

Modulation of GnRH subtypes by social stress and aggressive behavior

The present study demonstrates that social dominance is a hierarchy of body size and that every adult male tilapia has the potential to become dominant depending upon the body size of his opponents. Further, we show chronic social stress down-regulates GnRH1-2 but not GnRH3 mRNAs levels, which could influence reproduction and reproductive behaviors.