To assess the impact of Bombus terrestris invasion on the foraging efficiency of native Japanese bumblebees, consumption and acquisition of floral resources during
foraging on flowers of native Japanese plant species were investigated using enclosures with three treatments: one with only
B. terrestris (exotic), one with both B. terrestris and native Japanese bumblebee species (mixed), and one with only Japanese species (native), but with the bumblebee density
held constant. Changes in the body mass of queens and the nest mass of colonies for two days did not significantly differ
among four combinations of the species and treatment, B. terrestris in the exotic and mixed treatments and Japanese species in the mixed and native treatments. Thus, it is not clear that B. terrestris has higher foraging efficiency than native species and that B. terrestris individuals more negatively affect the foraging efficiency of native species than individuals of the native species themselves.
The nectar standing crop of Cirsium kamtschaticum was smaller in the exotic treatment than in the mixed and native treatments. However, this may have been an artifact of differences
in the numbers of flowers in the various treatments.
T. Nagamitsu and T. Kenta contributed equally to this work 相似文献
NHE1/SLC9A1 is a ubiquitous isoform of vertebrate Na+/H+ exchangers (NHEs) functioning in maintaining intracellular concentrations of Na+ and H+ ions. Calcineurin homologous protein-1 (CHP1) binds to the hydrophilic region of NHE1 and regulates NHE1 activity but reportedly does not play a role in translocating NHE1 from the endoplasmic reticulum to the plasma membrane. However, an antiport function of NHE1 requiring CHP1 remains to be clarified. Here we established CHP1-deficient chicken B lymphoma DT40 cells by gene targeting to address CHP1 function. CHP1-deficient cells showed extensive decreases in Na+/H+ activities in intact cells. Although NHE1 mRNA levels were not affected, NHE1 protein levels were significantly reduced not only in the plasma membrane but in whole cells. The expression of a CHP1 transgene in CHP1-deficient cells rescued NHE1 protein expression. Expression of mutant forms of CHP1 defective in Ca2+ binding or myristoylation also partially decreased NHE1 protein levels. Knockdown of CHP1 also caused a moderate decrease in NHE1 protein in HeLa cells. These data indicate that CHP1 primarily plays an essential role in stabilization of NHE1 for reaching of NHE1 to the plasma membrane and its exchange activity. membrane protein; transporter; antiporter; quality control; degradation 相似文献
Two classical mouse hair coat mutations, Rex (Re) and Rex wavy coat (Re(wc)), are linked to the type I inner root sheath (IRS) keratin genes of chromosome 11. An N-ethyl-N-nitrosourea-induced mutation, M100573, also maps close to the type I IRS keratin genes. In this study, we demonstrate that Re and M100573 mice bear mutations in the type I IRS gene Krt25; Re(wc) mice bear an additional mutation in the type I IRS gene Krt27. These three mutations are located in the helix termination motif of the 2B alpha-helical rod domain of a type I IRS keratin protein. Immunohistological analysis revealed abnormal foam-like immunoreactivity with an antibody raised to type II IRS keratin K71 in the IRS of Re/+ mice. These results suggest that the helix termination motif is essential for the proper assembly of types I and II IRS keratin protein complexes and the formation of keratin intermediate filaments. 相似文献
Mammal-fish-conserved-sequence 1 (MFCS1) is a highly conserved sequence that acts as a limb-specific cis-acting regulator of Sonic hedgehog (Shh) expression, residing 1 Mb away from the Shh coding sequence in mouse. Using gene-driven screening of an ENU-mutagenized mouse archive, we obtained mice with three new point mutations in MFCS1: M101116, M101117, and M101192. Phenotype analysis revealed that M101116 mice exhibit preaxial polydactyly and ectopic Shh expression at the anterior margin of the limb buds like a previously identified mutant, M100081. In contrast, M101117 and M101192 show no marked abnormalities in limb morphology. Furthermore, transgenic analysis revealed that the M101116 and M100081 sequences drive ectopic reporter gene expression at the anterior margin of the limb bud, in addition to the normal posterior expression. Such ectopic expression was not observed in the embryos carrying a reporter transgene driven by M101117. These results suggest that M101116 and M100081 affect the negative regulatory activity of MFCS1, which suppresses anterior Shh expression in developing limb buds. Thus, this study shows that gene-driven screening for ENU-induced mutations is an effective approach for exploring the function of conserved, noncoding sequences and potential cis-regulatory elements. 相似文献
Cells in the white matter of the adult brain have a characteristic distribution pattern in which several cells are contiguously connected to each other, making a linear array (LA) resembling pearls-on-a-string parallel to the axon axis. We have been interested in how this pattern of cell distribution changes during aging and remyelination after demyelination. In the present study, with a multiplex staining method, semi-quantitative analysis of the localization of oligodendrocyte lineage cells (oligodendrocyte progenitors, premyelinating oligodendrocytes, and mature oligodendrocytes), astrocytes, and microglia in 8-week-old (young adult) and 32-week-old (aged) corpus callosum showed that young adult cells still include immature oligodendrocytes and that LAs contain a higher proportion of microglia than isolated cells. In aged mice, premyelinating oligodendrocytes were decreased, but microglia continued to be present in the LAs. These results suggest that the presence of microglia is important for the characteristic cell localization pattern of LAs. In a cuprizone-induced demyelination model, we observed re-formation of LAs after completion of cuprizone treatment, concurrent with remyelination. These re-formed LAs again contained more microglia than the isolated cells. This finding supports the hypothesis that microglia contribute to the formation and maintenance of LAs. In addition, regardless of the distribution of cells (LAs or isolated cells), astrocytes were found to be more abundant than in the normal corpus callosum at 24 weeks after cuprizone treatment when remyelination is completed. This suggests that astrocytes are involved in maintaining the functions of remyelinated white matter.
Lamellarin α and six different types of lamellarin α 20-sulfate analogues were synthesized and their structure–activity relationships were investigated using a single round HIV-1 vector infection assay. All lamellarin sulfates having pentacyclic lamellarin core exhibited anti-HIV-1 activity at a 10 μM concentration range regardless of the number and position of the sulfate group. On the other hand, non-sulfated lamellarin α and ring-opened lamellarin sulfate analogues did not affect HIV-1 vector infection in similar concentrations. The lamellarin sulfates utilized in this study did not exhibit unfavorable cytotoxic effect under the concentrations tested (IC50 > 100 μM). Confocal laser scanning microscopic analysis indicated that hydrophilic lamellarin sulfates were hardly incorporated in the cell. HIV-1 Env-mediated cell–cell fusion was suppressed by lamellarin sulfates. These results suggested that lamellarin sulfates have a novel anti-HIV-1 activity besides the previously reported integrase activity inhibition, possibly at a viral entry step of HIV-1 replication. 相似文献
Vasorelaxant effects of a series of bis(bibenzyls) from liverworts such as Marchantia polymorpha and Marchantia paleacea on rat aorta demonstrated that they relaxed phenylephrine (PE)-induced contractions, which may be mediated through the increased release of NO from endothelial cells as well as opening of K(+) channels, and inhibition of Ca(2+) influx through voltage-dependent Ca(2+) channels (VDCs) and/or receptor-operated Ca(2+) channels (ROCs). Structure-activity relationship based on their structures was discussed. The presence of two aromatic rings which can be connected through two atoms bridge spacer may play an important role for vasorelaxant effect. 相似文献
The gesneriaceous perennial plant Titanotrichum oldhamii has beautiful foliage and attractive bright yellow flowers. However, breeding of T. oldhamii by conventional sexual hybridization may be difficult because sexual reproduction of this species is very rare. In the present
study, plant regeneration systems via both direct and indirect formation of adventitious shoots from leaf explants were established
as the first step toward breeding T. oldhamii by using biotechnological techniques. Adventitious shoots were formed efficiently on medium containing 0.1 mg l−1 benzyladenine. Histological observation showed that shoot formation on this medium occurred directly from leaf epidermal
cells without callus formation. On the other hand, leaf explants formed calluses on medium containing 0.1 mg l−1 2,4-dichlorophenoxyacetic acid. The calluses could be maintained by monthly subculturing to fresh medium of the same composition.
When the calluses were transferred to plant growth regulator-free medium, they formed adventitious shoots. Directly and indirectly
formed shoots rooted well on medium containing 0.1 mg l−1 indole-3-butyric acid. Plantlets thus obtained were successfully acclimatized and grew vigorously in the greenhouse. Flow
cytometry analysis indicated that no variation in the ploidy level was observed in plants regenerated via direct shoot formation,
whereas chromosome doubling occurred in several plants regenerated via indirect shoot formation. Regenerated plants with the
same ploidy level as the mother plants showed almost the same phenotype as the mother plants, whereas chromosome-doubled plants
showed apparent morphological alterations: they had small and crispate flowers, and round and deep green leaves. 相似文献