Regulation of Glycolysis by Pdk Functions as a Metabolic Checkpoint for Cell Cycle Quiescence in Hematopoietic Stem Cells

1. Download : Download high-res image (269KB)
2. Download : Download full-size image

Highlights? LT-HSCs activate glycolysis and generate ATP in a HIF-1α-dependent manner ? Pdk overexpression in HIF-1α^Δ/Δ HSCs restored glycolysis and stem cell capacity ? Pdk2^?/?: Pdk4^?/? LT-HSCs show defective glycolysis and cell cycle quiescence ? Pdk mimetic promotes the survival and transplantation capacity of LT-HSCs     

Nematomorph parasites indirectly alter the food web and ecosystem function of streams through behavioural manipulation of their cricket hosts

Nematomorph parasites manipulate crickets to enter streams where the parasites reproduce. These manipulated crickets become a substantial food subsidy for stream fishes. We used a field experiment to investigate how this subsidy affects the stream community and ecosystem function. When crickets were available, predatory fish ate fewer benthic invertebrates. The resulting release of the benthic invertebrate community from fish predation indirectly decreased the biomass of benthic algae and slightly increased leaf break-down rate. This is the first experimental demonstration that host manipulation by a parasite can reorganise a community and alter ecosystem function. Nematomorphs are common, and many other parasites have dramatic effects on host phenotypes, suggesting that similar effects of parasites on ecosystems might be widespread.     

Electrochemical potential of protons in vesicles reconstituted from purified,proton-translocating adenosine triphosphatase

Summary Measurements were made of the difference in the electrochemical potential of protons ( ) across the membrane of vesicles reconstituted from the ATPase complex (TF ₀ ·F ₁) purified from a thermophilic bacterium and P-lipids. Two fluorescent dyes, anilinonaphthalene sulfonate (ANS) and 9-aminoacridine (9AA) were used as probes for measuring the membrane potential () and pH difference across the membrane ( pH), respectively.In the presence of Tris buffer the maximal and no pH were produced, while in the presence of the permeant anion NO ₃ ^– the maximal pH and a low were produced by the addition of ATP. When the ATP concentration was 0.24mm, the was 140–150 mV (positive inside) in Tris buffer, and the pH was 2.9–3.5 units (acidic inside) in the presence of NO ₃ ^– . Addition of a saturating amount of ATP produced somewhat larger and pH values, and the attained was about 310 mV.By trapping pH indicators in the vesicles during their reconstitution it was found that the pH inside the vesicles was pH 4–5 during ATP hydrolysis.The effects of energy transfer inhibitors, uncouplers, ionophores, and permeant anions on these vesicles were studied.     

ATP synthase that lacks F0a-subunit: isolation, properties, and indication of F0b2-subunits as an anchor rail of a rotating c-ring

In a rotary motor F1F0-ATP synthase, F0 works as a proton motor; the oligomer ring of F0c-subunits (c-ring) rotates relative to the F0ab2 domain as protons pass through F0 down the gradient. F0ab2 must exert dual functions during rotation, that is, sliding the c-ring (motor drive) while keeping the association with the c-ring (anchor rail). Here we have isolated thermophilic F1F0(-a) which lacks F0a. F1F0(-a) has no proton transport activity, and F0(-a) does not work as a proton channel. Interestingly, ATPase activity of F1F0(-a) is greatly suppressed, even though its F1 sector is intact. Most likely, F0b2 associates with the c-ring as an anchor rail in the intact F1F0; without F0a, this association prevents rotation of the c-ring (and hence the gamma-subunit), which disables ATP hydrolysis at F1. Functional F1F0 is easily reconstituted from purified F0a and F1F0(-a), and thus F0a can bind to its proper location on F1F0(-a) without a large rearrangement of other-subunits.     

Genetic Diversity on 16S rDNA Sequence and Phylogenic Tree Analysis in Pasteurella pneumotropica Strains Isolated from Laboratory Animals

To reveal the genetic diversity of Pasteurella pneumotropica, the 16S rDNA sequence and multiple alignments were performed for 35 strains (from 17 mice, 13 rats, 3 hamsters, 1 rabbit, and 1 guinea pig) identified as P. pneumotropica using a commercial biochemical test kit or PCR test and two reference strains (ATCC 35149 and CNP160). Each strain showed a close similarity with one of the following organisms: P. pneumotropica (M75083), Bisgaard taxon22 (AY172726), Pasteurella sp. MCCM00235 (AF224300), Pasteurellaceae gen. sp. Forsyth A3 (AF224301), and Actinobacillus muris (AF024526) on GenBank, and were divided into six clusters on a phylogenic tree. Two reference strains, P. pneumotropica biotype Jawetz and Heyl, were classified at both ends of the clusters. Our conclusion is that P. pneumotropica should be reclassified because of the very wide genetic diversity that exists.     

PCDH10 is required for the tumorigenicity of glioblastoma cells

Protocadherin10 (PCDH10)/OL-protocadherin is a cadherin-related transmembrane protein that has multiple roles in the brain, including facilitating specific cell–cell connections, cell migration and axon guidance. It has recently been reported that PCDH10 functions as a tumor suppressor and that its overexpression inhibits proliferation or invasion of multiple tumor cells. However, the function of PCDH10 in glioblastoma cells has not been elucidated. In contrast to previous reports on other tumors, we show here that suppression of the expression of PCDH10 by RNA interference (RNAi) induces the growth arrest and apoptosis of glioblastoma cells in vitro. Furthermore, we demonstrate that knockdown of PCDH10 inhibits the growth of glioblastoma cells xenografted into immunocompromised mice. These results suggest that PCDH10 is required for the proliferation and tumorigenicity of glioblastoma cells. We speculate that PCDH10 may be a promising target for the therapy of glioblastoma.     

Heterogeneity in spatial P-distribution and foraging capability by Zea mays: effects of patch size and barriers to restrict root proliferation within a patch

• Background and Aims Localized proliferation of rootsin nutrient-enriched patches seems to be an adaptive responsein many plants, but its function is still debatable. To understandthe efficiency and limitation of foraging behaviour, the impactof patch size and the presence or absence of a barrier to rootproliferation within phosphorus (P)-enriched patches was examined. • Methods In pots filled with P-poor soil, six treatmentsof heterogeneous P supply were prepared: three patch sizes withor without a root barrier between patches. In addition, a homogeneousP supply treatment was also prepared. Irrespective of thesetreatments, each pot received the same total amount of P. Maize(Zea mays) was grown in each pot for 45 d in a greenhouse. • Key Results P content and biomass were greatest in plantsgrown in the largest patch due to successful root proliferation,and were higher in the presence of a root barrier. Interestingly,plants preferentially developed adventitious nodal roots projectingfrom the stem into the P-enriched soil, particularly in thelargest patch with a root barrier. Removal of the barrier reducedthe P-uptake capacity per unit root surface area or volume inP-enriched patches, revealing that the P-uptake capacity perroot can be suppressed even in P-rich soil if other portionson the root axis encounter P-poor conditions. • Conclusions The results suggest that the efficiency ofroot morphological plasticity is largely determined by the sizeof the P-enriched patch. Furthermore, the results imply a novelaspect of P-uptake physiology that roots in heterogeneous Pcannot demonstrate their potential capacity, as would be observedin roots encountering P continuously; this effect is probablymediated by an internal root factor.     

A skin color mutation of grapevine, from black-skinned Pinot Noir to white-skinned Pinot Blanc, is caused by deletion of the functional VvmybA1 allele

A white-wine grape, Pinot Blanc, is thought to be a white-skinned mutant of a red-wine grape, Pinot Noir. Pinot Noir was heterozygous for VvmybA1. One allele was the non-functional VvmybA1a, and the other was the functional VvmybA1c. In Pinot Blanc, however, only VvmybA1a was observed, and the amount of VvmybA1 DNA in Pinot Blanc was half that in Pinot Noir. These findings suggest that deletion of VvmybA1c from Pinot Noir resulted in Pinot Blanc.