Breakdown in seasonal dynamics of subtropical ant communities with land-cover change.

Concerns about widespread human-induced declines in insect populations are mounting, yet little is known about how land-use change modifies both the trends and variability of insect communities, particularly in understudied regions. Here, we examine how the seasonal activity patterns of ants-key drivers of terrestrial ecosystem functioning-vary with anthropogenic land-cover change on a subtropical island landscape, and whether differences in temperature or species composition can explain observed patterns. Using trap captures sampled biweekly over 2 years from a biodiversity monitoring network covering Okinawa Island, Japan, we processed 1.2 million individuals and reconstructed activity patterns within and across habitat types. Forest communities exhibited greater temporal variability of activity than those in more developed areas. Using time-series decomposition to deconstruct this pattern, we found that sites with greater human development exhibited ant communities with diminished seasonality, reduced synchrony and higher stochasticity compared with sites with greater forest cover. Our results cannot be explained by variation in regional or site temperature patterns, or by differences in species richness or composition among sites. Our study raises the possibility that disruptions to natural seasonal patterns of functionally key insect communities may comprise an important and underappreciated consequence of global environmental change that must be better understood across Earth's biomes.

Identification of guanine, guanosine, and inosine for α-amylase inhibitors in the extracts of the earthworm Eisenia fetida and characterization of their inhibitory activities against porcine pancreatic α-amylase.

Earthworms are known as a source of a traditional medicine, and bioactive components have been reported. We have reported that a fraction (U3EE) with molecular mass under 3 kDa from the water extract of Eisenia fetida inhibits porcine pancreatic α-amylase (PPA) activity with a half-maximal inhibitory concentration (IC50) of 73.7 ±â€¯4.0 mg/mL. Here we purified PPA-inhibitory components from U3EE by sequential procedures of 85 %-ethanol (EtOH) extraction, solid-phase extraction (SPE), and RP-HPLC. The water eluate from SPE of the 85 %-EtOH extract was a major inhibitory fraction, from which three components were separated by 2nd RP-HPLC and identified with MS, TLC, and UV spectroscopy as guanine (Gua), inosine (Ino), and guanosine (Guo). Kinetic analysis showed that Gua and Guo were non-competitive inhibitors and Ino a mixed-type one, suggesting a key role of the purine ring in inhibition. The inhibitor constants (Ki) of Gua and Guo were 0.28 ±â€¯0.07 and 1.64 ±â€¯0.14 mM, respectively, and Ki and Ki' of Ino in the EI and ESI complexes were 5.8 ±â€¯1.1 and 59 ±â€¯12 mM, respectively. U3EE might be useful for food supplements to prevent obesity and diabetes.

Exploration of dipeptidyl-peptidase IV (DPP IV) inhibitors in a low-molecular mass extract of the earthworm Eisenia fetida and identification of the inhibitors as amino acids like methionine, leucine, histidine, and isoleucine.

We have reported previously that the water extract of the earthworm Eisenia fetida has inhibitory effect on human dipeptidyl-peptidase IV (DPP IV) in vitro. Here we studied to identify DPP IV inhibitors in a low-molecular mass extract (designated U3EE) under 3 kDa prepared from the water extract. U3EE showed 50 % inhibition (IC50) at the concentration of 5.3 ± 0.3 mg/mL. An inhibitory active fraction obtained by solid-phase extraction of U3EE was separated into three parts by reversed-phase HPLC. These parts were shown by GC/MS to be composed of ten (Ala, Gly, Thr, Ser, Asn, Asp, Lys, His, Orn, and cystine), two (Leu and Ile), and one (Met) amino acids, respectively. Among them, Met, Leu, and His showed strong inhibition with IC50 values of 3.4 ± 0.3, 6.1 ± 0.3 and 14.7 ± 1.2 mM, respectively; Ala, Lys, Orn, and Ile showed rather weaker inhibition than those, while the others showed no inhibition. Met, Leu, and Ile were competitive inhibitors and His was a mixed-type one. DPP IV inhibition by U3EE might be due to additive and/or synergistic effects of the inhibitory amino acids, suggesting that it could be useful as pharmaceutical and supplement for diabetes prevention.

Activating effects on trypsin, α-chymotrypsin, and lipase and inhibitory effects on α-amylase and α-glucosidase as provided by low-molecular-weight compounds in the water extract of the earthworm Eisenia fetida.

A fraction (designated as U3EE) with molecular mass under 3 kDa from the water extract of the earthworm Eisenia fetida was prepared and its effects on mammalian digestive enzymes were examined. U3EE itself showed no relevant enzyme activities. However, it increased the activities of trypsin, α-chymotrypsin, and lipase, while decreased those of α-amylase and α-glucosidase. The trypsin activation and α-amylase inhibition were analyzed precisely by enzyme kinetics. The former was solely dependent on increase in the molecular activity kcat without any change in the Michaelis constant Km, and the latter was mainly dependent on decrease in Km with a slight change in kcat. Effects of the treatments of U3EE with freezing-and-thawing, heat, acid, and hexane were examined. The treated U3EE showed the effects on the enzymes with the same potencies as those provided by the non-treated one, indicating that U3EE was enough stable toward the harsh treatments to hold the modulating effects on the enzyme activities. U3EE was also shown to be highly hydrophilic. The results obtained in this paper suggested that U3EE could be applicable as a novel constituent for pharmaceuticals and functional foods.