Maki N. Inoue

Bio: Maki N. Inoue is an academic researcher from Tokyo University of Agriculture and Technology. The author has contributed to research in topics: Bombus terrestris & Biology. The author has an hindex of 14, co-authored 56 publications receiving 922 citations. Previous affiliations of Maki N. Inoue include University of Tokyo & National Institute for Environmental Studies.

Displacement of Japanese native bumblebees by the recently introduced Bombus terrestris (L.) (Hymenoptera: Apidae)

Abstract: The introduced Bombus terrestris has recently been naturalized in Japan and become dominant in some local communities. We investigated potential niche overlaps between introduced and native bumblebees in terms of morphological characteristics, seasonal flight activity, foraging and nesting habitat use, and plant species visited. There were considerable niche overlaps in flower resource use between B. terrestris and B. hypocrita sapporoensis/B. pseudobaicalensis. Bombus terrestris also potentially competes for nest sites with B. hypocrita sapporoensis. During 3-year monitoring, B. pseudobaicalensis showed no noticeable change, but B. hypocrita sapporoensis decreased while B. terrestris increased. Abundant flower resources provided by exotic plants may buffer native bumblebees from competition for food with introduced species. By contrast, the number of nest usurpers found in B. terrestris nests increased between 2003 and 2005, indicating that availability of nest sites was limiting and queens strongly competed for nest sites. Our findings suggest that competition for nest sites rather than flower resources is the major ecological mechanism for displacement of native bees. The large reduction of B. hypocrita sapporoensis queen indicates that B. terrestris may cause local extinction of native bumblebees. Control of established B. terrestris populations and prevention of further range expansion are urgently needed.

Meiotic abnormalities of c-mos knockout mouse oocytes: activation after first meiosis or entrance into third meiotic metaphase.

Abstract: In Xenopus oocytes, Mos activates the mitogen-activated protein kinase (MAPK) signal transduction cascade and regulates meiosis. In mammalian oocytes, however, the functions of Mos are still unclear. In the present study, we used c-mos knockout mouse oocytes and examined the roles of Mos in mouse oocyte maturation and fertilization, including whether Mos controls MAPK and maturation promoting factor (MPF) activity. The kinetics of germinal vesicle breakdown (GVBD) and the first polar body emission were similar in wild-type, heterozygous mutant, and homozygous mutant mice. Activities of MPF were also not significantly different among the three genotypes until the first polar body emission. In contrast, MAPK activity in c-mos knockout oocytes did not significantly fluctuate throughout maturation, and the oocytes had abnormal diffused spindles and loosely condensed chromosomes, although a clear increase in MAPK activities was observed after GVBD in wild-type and heterozygous mutant oocytes that had normal spindles and chromosomes. After the first polar body emission, 38% of c-mos knockout oocytes formed a pronucleus instead of undergoing second meiosis, indicating the crucial role of Mos in MPF reactivation after first meiosis. When oocytes that reached second metaphase were fertilized or stimulated by ethanol, many c-mos knockout oocytes emitted a second polar body and progressed into third meiotic metaphase instead of interphase, although all fertilized or activated oocytes in the heterozygote progressed to interphase, indicating that Mos deletion leads to compensatory factors that might not be degraded after fertilization or parthenogenetic activation. These results suggest that Mos is located upstream of MAPK in mouse oocytes as in Xenopus oocytes but is independent of MPF activity, and that Mos/MAPK is not necessary for GVBD and first polar body emission. Our results also suggest that Mos plays a crucial role in normal spindle and chromosome morphology and the reactivation of MPF after first meiosis.

Activation of mitogen-activated protein kinase during meiotic maturation in porcine oocytes

Abstract: To investigate the involvement of mitogen-activated protein kinase (MAP kinase) in meiotic maturation of porcine oocytes, we assayed MAP kinase activity using myelin basic protein (MBP) as a substrate. MAP kinase activity was low during the germinal vesicle stage, 0-20 h of culture. An abrupt increase was observed at metaphase I (30 h of culture), and activity remained significantly higher than that at 0 h until 50 h of culture, with a transient slight decrease at the time of first polar body extrusion (40 h). Detection of the kinase activity by an in-gel phosphorylation assay confirmed that the 42 and 44 kDa MAP kinases were significantly activated in 45 h cultured oocytes but not in 0 h oocytes, and just slightly in 20 h oocytes. In immunoblotting, however, the 42 and 44 kDa bands were detected in 0, 20 and 45 h cultured oocytes. Furthermore, the signal strength of the two bands did not change during the period of culture, but shifted up to 45 h, indicating that the activation of MAP kinase depended not on the synthesis but on the phosphorylation of this enzyme. These results suggest that the activation of MAP kinase is involved in the regulation of meiotic maturation of porcine oocytes, and especially in the regulation after germinal vesicle breakdown.

Mitogen-activated protein kinase translocates into the germinal vesicle and induces germinal vesicle breakdown in porcine oocytes.

Abstract: The role of mitogen-activated protein kinase (MAPK) in the meiotic resumption of porcine oocytes was examined. First, using indirect immunofluorescence staining with a specific antibody against rat MAPK, we monitored the dynamics of the subcellular distribution of MAPK during meiosis initiation. We found that the inactive MAPK was already present in immature oocytes arrested at the G2 stage and that this inactive kinase was localized exclusively in the cytoplasm. At the G2/M transition stage, part of the MAPK moved into the germinal vesicle (GV) before germinal vesicle breakdown (GVBD). In addition, immunoblot analysis showed that the nuclear MAPK existed in an active form. To determine whether this active MAPK could induce GVBD, we microinjected active MAPK into immature porcine oocytes. The active MAPK injected into the cytoplasm was quickly inactivated and could not accelerate GVBD. In contrast, MAPK injection into the GV markedly accelerated GVBD. These results show that in porcine oocytes, 1) inactive MAPK localizes in the cytosol of immature GV oocytes, 2) part of the activated MAPK translocates into the GV just before GVBD, and 3) exogenous MAPK maintains its activity level in the GV and induces GVBD, indicating that MAPK mediates the maturation-inducing signal from the cytoplasm into the nucleus and induces meiosis reinitiation.

Identification of Reliable Components in Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS): a Data-Driven Approach across Metabolic Processes.

Abstract: There is an increasing need to use multivariate statistical methods for understanding biological functions, identifying the mechanisms of diseases, and exploring biomarkers. In addition to classical analyses such as hierarchical cluster analysis, principal component analysis, and partial least squares discriminant analysis, various multivariate strategies, including independent component analysis, non-negative matrix factorization, and multivariate curve resolution, have recently been proposed. However, determining the number of components is problematic. Despite the proposal of several different methods, no satisfactory approach has yet been reported. To resolve this problem, we implemented a new idea: classifying a component as "reliable" or "unreliable" based on the reproducibility of its appearance, regardless of the number of components in the calculation. Using the clustering method for classification, we applied this idea to multivariate curve resolution-alternating least squares (MCR-ALS). Comparisons between conventional and modified methods applied to proton nuclear magnetic resonance ((1)H-NMR) spectral datasets derived from known standard mixtures and biological mixtures (urine and feces of mice) revealed that more plausible results are obtained by the modified method. In particular, clusters containing little information were detected with reliability. This strategy, named "cluster-aided MCR-ALS," will facilitate the attainment of more reliable results in the metabolomics datasets.

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Bee declines driven by combined stress from parasites, pesticides, and lack of flowers

Abstract: Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.

Evolution of life in urban environments.

Abstract: BACKGROUND The extent of urban areas is increasing around the world, and most humans now live in cities. Urbanization results in dramatic environmental change, including increased temperatures, more impervious surface cover, altered hydrology, and elevated pollution. Urban areas also host more non-native species and reduced abundance and diversity of many native species. These environmental changes brought by global urbanization are creating novel ecosystems with unknown consequences for the evolution of life. Here, we consider how early human settlements led to the evolution of human commensals, including some of the most notorious pests and disease vectors. We also comprehensively review how contemporary urbanization affects the evolution of species that coinhabit cities. ADVANCES A recent surge of research shows that urbanization affects both nonadaptive and adaptive evolution. Some of the clearest results of urban evolution show that cities elevate the strength of random genetic drift (stochastic changes in allele frequencies) and restrict gene flow (the movement of alleles between populations due to dispersal and mating). Populations of native species in cities often represent either relicts that predate urbanization or populations that established after a city formed. Both scenarios frequently result in a loss of genetic diversity within populations and increased differentiation between populations. Fragmentation and urban infrastructure also create barriers to dispersal, and consequently, gene flow is often reduced among city populations, which further contributes to genetic differentiation between populations. The influence of urbanization on mutation and adaptive evolution are less clear. A small number of studies suggest that industrial pollution can elevate mutation rates, but the pervasiveness of this effect is unknown. A better studied phenomenon are the effects of urbanization on evolution by natural selection. A growing number of studies show that plant and animal populations experience divergent selection between urban and nonurban environments. This divergent selection has led to adaptive evolution in life history, morphology, physiology, behavior, and reproductive traits. These adaptations typically evolve in response to pesticide use, pollution, local climate, or the physical structure of cities. Despite these important results, the genetic basis of adaptive evolution is known from only a few cases. Most studies also examine only a few populations in one city, and experimental validation is rare. OUTLOOK The study of evolution in urban areas provides insights into both fundamental and applied problems in biology. The thousands of cities throughout the world share some features while differing in other aspects related to their age, historical context, governmental policies, and local climate. Thus, the phenomenon of global urbanization represents an unintended but highly replicated global study of experimental evolution. We can harness this global urban experiment to understand the repeatability and pace of evolution in response to human activity. Among the most important unresolved questions is, how often do native and exotic species adapt to the particular environmental challenges found in cities? Such adaptations could be the difference as to whether a species persists or vanishes from urban areas. In this way, the study of urban evolution can help us understand how evolution in populations may contribute to conservation of rare species, and how populations can be managed to facilitate the establishment of resilient and sustainable urban ecosystems. In a similar way, understanding evolution in urban areas can lead to improved human health. For example, human pests frequently adapt to pesticides and evade control efforts because of our limited understanding of the size of populations and movement of individuals. Applied evolutionary studies could lead to more effective mitigation of pests and disease agents. The study of urban evolution has rapidly become an important frontier in biology, with implications for healthy and sustainable human populations in urban ecosystems.

Bumblebee vulnerability and conservation world-wide

Abstract: We review evidence from around the world for bumblebee declines and review management to mitigate threats. We find that there is evidence that some bumblebee species are declining in Europe, North America, and Asia. People believe that land-use changes may be having a negative effect through reductions in food plants in many parts of the world, but that other factors such as pathogens may be having a stronger effect for a few species in some regions (especially for Bombus s. str. in North America). Evidence so far is that greater susceptibility to land-use change is associated world-wide with small climatic ranges, range edges, and late-starting colony-development cycles. More evidence is needed on the roles of pollen specialization, nest sites, hibernation sites, and pesticides. It is still too early to assess the success of schemes aimed at improving forage in agricultural and conservation areas. However, schemes aimed at raising public awareness have been very successful. Until proven safe, we recommend that live bumblebees should not be moved across continents or oceans for commercial pollination.