Ionic composition and pH of the vacuolar sap in marine dinoflagellate Noctiluca

Ionic composition of the vacuolar sap of Noctiluca miliariswas as follows: [Na⁺] = 487.3 mM, [K⁺]=24.1 mM, [Ca²⁺]=6.6 mM,[Mg²⁺]=2.8 mM, [Cl^–]=500mM, [NH₄⁺]=15–25 mM, and[SO₄^2–]=undetectable. To measure the vacuolar pH of singleliving cells, a pH-sensitive glass microelectrode was used.The vacuolar pH value was 3.50 ±0.18. When the cellswere transferred from normal sea water into osmotically adjusted50% sea water for one day, the vacuolar ion concentrations remainedalmost constant. Upon immersing the cells in osmotically unadjustedsea water of various concentrations for one day, the observedincrements or decrements of the vacuolar ion concentrationscould be accounted for largely by the migration of water outof or into the cells. The intrinsic ionic composition of thevacuole seems to be constant against changes in ion concentrationsof the bathing medium. (Received October 20, 1975; )     

Impaired UTP-induced relaxation in the carotid arteries of spontaneously hypertensive rats

Uridine 5′-triphosphate (UTP) has an important role as an extracellular signaling molecule that regulates inflammation, angiogenesis, and vascular tone. While chronic hypertension has been shown to promote alterations in arterial vascular tone regulation, carotid artery responses to UTP under hypertensive conditions have remained unclear. The present study investigated carotid artery responses to UTP in spontaneously hypertensive rats (SHR) and control Wistar Kyoto rats (WKY). Accordingly, our results found that although UTP promotes concentration-dependent relaxation in isolated carotid artery segments from both SHR and WKY after pretreatment with phenylephrine, SHR exhibited significantly lower arterial relaxation responses compared with WKY. Moreover, UTP-induced relaxation was substantially reduced by endothelial denudation and by the nitric oxide (NO) synthase inhibitor N^G-nitro-L-arginine in both SHR and WKY. The difference in UTP-induced relaxation between both groups was abolished by the selective P2Y₂ receptor antagonist AR-C118925XX and the cyclooxygenase (COX) inhibitor indomethacin but not by the thromboxane-prostanoid receptor antagonist SQ29548. Furthermore, we detected the release of PGE₂, PGF_2α, and PGI₂ in the carotid arteries of SHR and WKY, both at baseline and in response to UTP. UTP administration also increased TXA₂ levels in WKY but not SHR. Overall, our results suggest that UTP-induced relaxation in carotid arteries is impaired in SHR perhaps due to impaired P2Y₂ receptor signaling, reductions in endothelial NO, and increases in the levels of COX-derived vasoconstrictor prostanoids.

     

Hermaphroditism in fishes: an annotated list of species,phylogeny, and mating system

Fewer than 1% of vertebrate species are hermaphroditic, and essentially all of these are fishes. Four types of hermaphroditism are known in fishes: simultaneous (or synchronous) hermaphroditism (SH), protandry (male-to-female sex change; PA), protogyny (female-to-male sex change; PG), and bidirectional sex change (BS or reversed sex change in protogynous species). Here we present an annotated list of hermaphroditic fish species from a comprehensive review and careful re-examination of all primary literature. We confirmed functional hermaphroditism in more than 450 species in 41 families of 17 teleost orders. PG is the most abundant type (305 species of 20 families), and the others are much less abundant, BS in 66 species of seven families, SH in 55 species of 13 families, and PA in 54 species of 14 families. The recently proposed phylogenetic tree indicated that SH and PA have evolved several times in not-closely related lineages of Teleostei but that PG (and BS) has evolved only in four lineages of Percomorpha. Examination of the relation between hermaphroditism type and mating system in each species mostly supported the size-advantage model that predicts the evolution of sequential hermaphroditism. Finally, intraspecific variations in sexual pattern are discussed in relation to population density, which may cause variation in mating system.

     

Factors influencing lifespan dependency on agricultural crops by brown bears

Landscape and Ecological Engineering - Investigating factors underlying human-wildlife conflicts in agricultural landscapes is important for both preventing crop damage and wildlife conservation....     

The biomechanical effect of the collar of a femoral stem on total hip arthroplasty

To investigate the biomechanical effect of collars, finite element analyses are carried out through two hip joints that are implanted using collared and collarless stems, respectively, and an intact hip joint model. For the analyses, the sacrum, coxal bone, and the cancellous and cortical bones of a femur are modelled using finite elements based on X-ray computed tomographic images taken from a 27-year-old woman. From the results, it is found that a collar with perfect calcar contact prevents stem subsidence and decreases the proximal–lateral gap and the lateral stem tilting. Therefore, it can impart reasonable biomechanical stability for total hip arthroplasty. However, its low load transmission ability and increased stem tilting effect due to the imperfect contact between the collar and the calcar are found to be serious problems that need to be solved. Results of clinical follow-up are presented for supporting the computational results.     

Development of DNA markers for identifying chrysanthemum cultivars generated by ion-beam irradiation

Four chrysanthemum cultivars were generated through (carbon) ion-beam irradiation of the original ‘Jimba’ (Chrysanthemum morifolium Ramat.). The new cultivars had acquired a number of superior cultivation traits, while remaining identical to the commercially available ‘Jimba’ in appearance. In this study, polymerase chain reaction (PCR) assays were used to detect the mutated region of each strain, thereby allowing clear identification at the molecular level. PCR assays were performed with 446 primer sets, including random amplified polymorphic DNA (RAPD) primer sets (10-mer RAPD), arbitrarily primed (AP)-PCR primers based on retrotransposon-like sequences and modified RAPD primers (15-mer RAPD). 15-mer RAPD primers generated a 1.49-fold increased band number at high annealing temperatures compared with the original 10-mer RAPD primers and could thus be effective for detection of polymorphic patterns. Our results provide information on the mutated regions of these ion-beam-irradiated chrysanthemum cultivars. Thus, specific DNA markers could be used to improve identification of new cultivars of chrysanthemum as well as other clonal cultivars of horticultural and agricultural crops.     

Cooperative Functions of ZnT1, Metallothionein and ZnT4 in the Cytoplasm Are Required for Full Activation of TNAP in the Early Secretory Pathway

The activation process of secretory or membrane-bound zinc enzymes is thought to be a highly coordinated process involving zinc transport, trafficking, transfer and coordination. We have previously shown that secretory and membrane-bound zinc enzymes are activated in the early secretory pathway (ESP) via zinc-loading by the zinc transporter 5 (ZnT5)-ZnT6 hetero-complex and ZnT7 homo-complex (zinc transport complexes). However, how other proteins conducting zinc metabolism affect the activation of these enzymes remains unknown. Here, we investigated this issue by disruption and re-expression of genes known to be involved in cytoplasmic zinc metabolism, using a zinc enzyme, tissue non-specific alkaline phosphatase (TNAP), as a reporter. We found that TNAP activity was significantly reduced in cells deficient in ZnT1, Metallothionein (MT) and ZnT4 genes (ZnT1 ^−/− MT ^−/− ZnT4 ^−/− cells), in spite of increased cytosolic zinc levels. The reduced TNAP activity in ZnT1 ^−/− MT ^−/− ZnT4 ^−/− cells was not restored when cytosolic zinc levels were normalized to levels comparable with those of wild-type cells, but was reversely restored by extreme zinc supplementation via zinc-loading by the zinc transport complexes. Moreover, the reduced TNAP activity was adequately restored by re-expression of mammalian counterparts of ZnT1, MT and ZnT4, but not by zinc transport-incompetent mutants of ZnT1 and ZnT4. In ZnT1 ^−/− MT ^−/− ZnT4 ^−/− cells, the secretory pathway normally operates. These findings suggest that cooperative zinc handling of ZnT1, MT and ZnT4 in the cytoplasm is required for full activation of TNAP in the ESP, and present clear evidence that the activation process of zinc enzymes is elaborately controlled.     

Calcium-Dependent Interaction Sites of Tropomyosin on Reconstituted Muscle Thin Filaments with Bound Myosin Heads as Studied by Site-Directed Spin-Labeling

To identify the interaction sites of Tm, we measured the rotational motion of a spin-label covalently bound to the side chain of a cysteine that was genetically incorporated into rabbit skeletal muscle tropomyosin (Tm) at positions 13, 36, 146, 160, 174, 190, 209, 230, 271, or 279. Most of the Tm residues were immobilized on actin filaments with myosin-S1 bound to them. The residues in the mid-portion of Tm, namely, 146, 174, 190, 209, and 230, were mobilized when the troponin (Tn) complex bound to the actin-Tm-S1 filaments. The addition of Ca²⁺ ions partially reversed the Tn-induced mobilization. In contrast, residues at the joint region of Tm, 13, 36, 271, and 279 were unchanged or oppositely changed. All of these changes were detected using a maleimide spin label and less obviously using a methanesulfonate label. These results indicated that Tm was fixed on thin filaments with myosin bound to them, although a small change in the flexibility of the side chains of Tm residues, presumably interfaced with Tn, actin and myosin, was induced by the binding of Tn and Ca²⁺. These findings suggest that even in the myosin-bound (open) state, Ca²⁺ may regulate actomyosin contractile properties via Tm.     

Inhibition of the Growth Factor MDK/Midkine by a Novel Small Molecule Compound to Treat Non-Small Cell Lung Cancer

Midkine (MDK) is a heparin-binding growth factor that is highly expressed in many malignant tumors, including lung cancers. MDK activates the PI3K pathway and induces anti-apoptotic activity, in turn enhancing the survival of tumors. Therefore, the inhibition of MDK is considered a potential strategy for cancer therapy. In the present study, we demonstrate a novel small molecule compound (iMDK) that targets MDK. iMDK inhibited the cell growth of MDK-positive H441 lung adenocarcinoma cells that harbor an oncogenic KRAS mutation and H520 squamous cell lung cancer cells, both of which are types of untreatable lung cancer. However, iMDK did not reduce the cell viability of MDK-negative A549 lung adenocarcinoma cells or normal human lung fibroblast (NHLF) cells indicating its specificity. iMDK suppressed the endogenous expression of MDK but not that of other growth factors such as PTN or VEGF. iMDK suppressed the growth of H441 cells by inhibiting the PI3K pathway and inducing apoptosis. Systemic administration of iMDK significantly inhibited tumor growth in a xenograft mouse model in vivo. Inhibition of MDK with iMDK provides a potential therapeutic approach for the treatment of lung cancers that are driven by MDK.     

Early Archean planktonic mode of life: Implications from fluid dynamics of lenticular microfossils

Lenticular, and commonly flanged, microfossils in 3.0–3.4 Ga sedimentary deposits in Western Australia and South Africa are unusually large (20–80 μm across), robust, and widespread in space and time. To gain insight into the ecology of these organisms, we performed simulations of fluid dynamics of virtual cells mimicking lenticular forms of variable sizes, oblateness, flange presence, and flange thickness. Results demonstrate that (a) the flange reduces sedimentation velocity, (b) this flange function works more effectively in larger cells, and (c) modest oblateness lowers sedimentation rate. These observations support interpretations that the lenticular microbes were planktonic—a lifestyle that could have been advantageous in an early Earth harsh environment including violent volcanic activities, repeated asteroid impacts, and relatively high UV‐radiation. Although the robustness of these organisms could have provided additional protection on the early Earth, this architecture may have impeded a planktonic lifestyle by increasing cell density. However, our data suggest that this disadvantage could have been compensated by enlargement of cell volume, which could have enhanced the ability of the flange to slow sedimentation rate, especially if coupled with vacuolation. The results of this simulation study may help to explain the unique morphology and unusually large size of these Archean microfossils.