Host plant conspicuousness and the distribution of eggs and larvae in the butterfly,Anthocharis scolymus (Lepidoptera: Pieridae)

We investigated how the distribution pattern of eggs and larval on the host plant, Turritus glabra, was influenced by the oviposition behavior of the pierid butterfly Anthocharis scolymus. Females searched for the host plants visually and they frequently approached taller host plants with sparse surrounding vegetation. After encountering host plants, oviposition behavior of females was independent of host plant characteristics such as height, density, and type of surrounding vegetation. A female laid eggs singly on a host plants. Most females appeared to lay their eggs regardless of the presense of eggs on the host plant. Consequently egg and larva tended to be abundant on conspicuous host plants as measured by height or relative isolation from other plants. However, overcrowding of eggs on an individual host decreased the survival rate of larvae.     

Competitive habitat utilization in the damselfly,Mnais nawai (Zygoptera: Calopterygidae) coexisting with a related species,Mnais pruinosa

Reproductive behaviors related to habitat utilization were studied in males of the damsefly,Mnais nawai, which has two male forms, territorial orange-winged males (nawai) and non-territorial pale-orange-winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species,Mnais pruinosa, which also has two male forms, territorial orange-winged males (esakii) and non-territorial hyaline-winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied byM. nawai, and the upper part byM. pruinosa. In the present study, cross-matings occurred between bothMnais species, although normal intraspecific matings occurred more frequently than cross-matings. Territorial males of both species copulated with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between the two species. On the other hand, non-territorial males of both species have alternative mating strategies (including several tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both species is discussed.     

Changes in levels of mRNAs of transforming growth factor (TGF)-β1, -β2, -β3, TGF-β type II receptor and sulfated glycoprotein-2 during apoptosis of mouse uterine epithelium

To examine the roles played by transforming growth factors (TGF)-β1, -β2, -β3, and TGF-β type II receptors in the induction of apoptosis in the mouse uterine epithelium after estrogen deprivation, we investigated the expression of their mRNAs and the mRNA of sulfated glycoprotein-2 (SGP-2). Pellets containing 100 μg estradiol-17β (E₂) were implanted into ovariectomized mice and removed four days later. Apoptotic indices (percentage of apoptotic cells) of both luminal and glandular epithelia increased after E₂ pellets were removed, but administration of progesterone (P), 5-dihydrotestosterone (DHT), or continued implantation of E₂ pellets suppressed this increase. Levels of mRNAs of TGF-β1, -β2, and -β3, and SGP-2 did not increase after estrogen deprivation. However, estrogen deprivation caused a gradual increase in the level of TGF-β type II receptor mRNA, and its level increased about six-fold six days later. Moreover, E₂, P, and DHT markedly decreased the level of TGF-β type II receptor mRNA. In situ hybridization demonstrated that mRNAs of TGF-β1, -β2, -β3 and TGF-β type II receptor were localized to the epithelium. Exogenous administration of TGF-β1 into the uterine stroma induced apoptosis in the epithelium, a finding that suggests that signals produced by TGF-βs can induce apoptosis. Therefore, the present results suggest that increased sensitivity of uterine epithelial cells to TGF-βs, as demonstrated by an increase in TGF-β type II receptor mRNA, is involved in the induction of apoptosis after estrogen deprivation, although signals produced by TGF-βs do not appear sufficient to induce apoptosis.     

O uptake rate measurements as a novel tool to study shear effects on suspended strawberry cells

Despite the same mean volumetric power input of 19 and 47 W/m 3 , the specific oxygen uptake rate (OUR S ) of strawberry ( Fragaria ananassa) cell suspensions was higher in bioreactors equipped with a Rushton Turbine (4.4 and 6.2 3 10 -5 mol O 2 /kg.s) than with an anchor stirrer (2.5 and 4.6 3 10 -5 mol O 2kg.s). The increase in OUR S was caused by stress-activated respiration and appeared to be correlated with the locally dissipated power input. OUR S was corrected for the increase in surface through aggregate break-up and reached a maximum of 6.0 3 10 -5 mol O 2kg.s when agitating with approximately 200 kW/m 3 locally dissipated power input.     

The Pro to glycine mutation of staphylococcal nuclease simplifies the unfolding—folding kinetics

Kinetics of unfolding and refolding of a staphylococcal nuclease mutant, in which Pro¹¹⁷ is replaced by glycine, have been investigated by stopped-flow circular dichroism, and the results are compared with those for the wild-type protein. In contrast to the biphasic unfolding of the wild-type nuclease, the unfolding of the mutant is represented by a single-phase reaction, indicating that the biphasic unfolding for the wild-type protein is caused by cis-trans isomerization about the prolyl peptide bond in the native state. The proline mutation also simplifies the kinetic refolding. Importance of the results in elucidating the folding mechanism is discussed.     

Autophagy in yeast demonstrated with proteinase-deficient mutants and conditions for its induction

For determination of the physiological role and mechanism of vacuolar proteolysis in the yeast Saccharomyces cerevisiae, mutant cells lacking proteinase A, B, and carboxypeptidase Y were transferred from a nutrient medium to a synthetic medium devoid of various nutrients and morphological changes of their vacuoles were investigated. After incubation for 1 h in nutrient-deficient media, a few spherical bodies appeared in the vacuoles and moved actively by Brownian movement. These bodies gradually increased in number and after 3 h they filled the vacuoles almost completely. During their accumulation, the volume of the vacuolar compartment also increased. Electron microscopic examination showed that these bodies were surrounded by a unit membrane which appeared thinner than any other intracellular membrane. The contents of the bodies were morphologically indistinguishable from the cytosol; these bodies contained cytoplasmic ribosomes, RER, mitochondria, lipid granules and glycogen granules, and the density of the cytoplasmic ribosomes in the bodies was almost the same as that of ribosomes in the cytosol. The diameter of the bodies ranged from 400 to 900 nm. Vacuoles that had accumulated these bodies were prepared by a modification of the method of Ohsumi and Anraku (Ohsumi, Y., and Y. Anraku. 1981. J. Biol. Chem. 256:2079-2082). The isolated vacuoles contained ribosomes and showed latent activity of the cytosolic enzyme glucose-6-phosphate dehydrogenase. These results suggest that these bodies sequestered the cytosol in the vacuoles. We named these spherical bodies "autophagic bodies." Accumulation of autophagic bodies in the vacuoles was induced not only by nitrogen starvation, but also by depletion of nutrients such as carbon and single amino acids that caused cessation of the cell cycle. Genetic analysis revealed that the accumulation of autophagic bodies in the vacuoles was the result of lack of the PRB1 product proteinase B, and disruption of the PRB1 gene confirmed this result. In the presence of PMSF, wild-type cells accumulated autophagic bodies in the vacuoles under nutrient-deficient conditions in the same manner as did multiple protease-deficient mutants or cells with a disrupted PRB1 gene. As the autophagic bodies disappeared rapidly after removal of PMSF from cultures of normal cells, they must be an intermediate in the normal autophagic process. This is the first report that nutrient-deficient conditions induce extensive autophagic degradation of cytosolic components in the vacuoles of yeast cells.     

Properties of H+-translocating adenosine triphosphatase in vacuolar membranes of SAccharomyces cerevisiae

The properties of Mg2+-ATPase in the vacuole of Saccharomyces cerevisiae were studied, using purified intact vacuoles and right-side-out vacuolar membrane vesicles prepared by the method of Y. Ohsumi and Y. Anraku ((1981) J. Biol. Chem. 256, 2079). The enzyme requires Mg2+ ion but not Ca2+ in. Cu2+ and Zn2+ ions inhibit the activity. The optimal pH is at pH 7.0. The enzyme hydrolyzes ATP, GTP, UTP, and CTP in this order and the Km value for ATP was determined as 0.2 mM. It does not hydrolyze ADP, adenosyl-5'-yl imidodiphosphate, or p-nitrophenyl phosphate. ADP does not inhibit hydrolysis of ATP by the enzyme. The activities of intact vacuoles and of vacuolar membrane vesicles were stimulated 3- and 1.5-fold, respectively, by the protonophore uncoupler 3,5-di-tert-butyl-4-hydroxybenzilidenemalononitrile and the K+/H+ antiporter ionophore nigericin. Sodium azide at a concentration exerting an uncoupler effect also stimulated the activity. The activity was sensitive to the ATPase inhibitor N,N'-dicyclohexylcarbodiimide, but not to sodium vanadate. The ATP-dependent formation of an electrochemical potential difference of protons, measured by the flow-dialysis method, was determined as 180 mV, with contribution of 1.7 pH units, interior acid, and of a membrane potential of 75 mV. It is concluded that the Mg2+-ATPase of vacuoles is a new marker enzyme for these organelles and is a N,N'-dicyclohexylcarbodiimide-sensitive, H+-translocating ATPase whose catalytic site is exposed to the cytoplasm.     

Proline in the Osmoregulation of Brevibacterium lactofermentum

Osmoregulation in Brevibacterium lactofermentum was studied. Proline was accumulated up to approximately 35mg/g dry cell weight in the cells of a wild strain of the bacterium grown under osmotic stress. The osmotic tolerance of a proline auxotroph mutant obtained from the bacterium was lower than that in the wild strain. The activity of pyrroline-5-carboxylate reductase, one of the enzymes in the proline biosynthetic pathway, increased about 3-fold when the cells of B. lactofermentum were grown under osmotic stress. These data indicated that proline is important in osmoregulation in the bacterium.     

Structure of the Atg12–Atg5 conjugate reveals a platform for stimulating Atg8–PE conjugation

Atg12 is conjugated to Atg5 through enzymatic reactions similar to ubiquitination. The Atg12–Atg5 conjugate functions as an E3‐like enzyme to promote lipidation of Atg8, whereas lipidated Atg8 has essential roles in both autophagosome formation and selective cargo recognition during autophagy. However, the molecular role of Atg12 modification in these processes has remained elusive. Here, we report the crystal structure of the Atg12–Atg5 conjugate. In addition to the isopeptide linkage, Atg12 forms hydrophobic and hydrophilic interactions with Atg5, thereby fixing its position on Atg5. Structural comparison with unmodified Atg5 and mutational analyses showed that Atg12 modification neither induces a conformational change in Atg5 nor creates a functionally important architecture. Rather, Atg12 functions as a binding module for Atg3, the E2 enzyme for Atg8, thus endowing Atg5 with the ability to interact with Atg3 to facilitate Atg8 lipidation.     

DNA methylation profiles provide a viable index for porcine pluripotent stem cells

Porcine induced pluripotent stem cells (iPSCs) provide useful information for translational research. The quality of iPSCs can be assessed by their ability to differentiate into various cell types after chimera formation. However, analysis of chimera formation in pigs is a labor‐intensive and costly process, necessitating a simple evaluation method for porcine iPSCs. Our previous study identified mouse embryonic stem cell (ESC)‐specific hypomethylated loci (EShypo‐T‐DMRs), and, in this study, 36 genes selected from these were used to evaluate porcine iPSC lines. Based on the methylation profiles of the 36 genes, the iPSC line, Porco Rosso‐4, was found closest to mouse pluripotent stem cells among 5 porcine iPSCs. Moreover, Porco Rosso‐4 more efficiently contributed to the inner cell mass (ICM) of blastocysts than the iPSC line showing the lowest reprogramming of the 36 genes (Porco Rosso‐622‐14), indicating that the DNA methylation profile correlates with efficiency of ICM contribution. Furthermore, factors known to enhance iPSC quality (serum‐free medium with PD0325901 and CHIR99021) improved the methylation status at the 36 genes. Thus, the DNA methylation profile of these 36 genes is a viable index for evaluation of porcine iPSCs. genesis 51:763–776. © 2013 Wiley Periodicals, Inc.