Selection for floral integration and trait variation in zygomorphic flowers of Aconitum japonicum ssp. subcuneatum (Ranunculaceae)

Pollinator-mediated selection might lead to among-trait differences in the degree and pattern of floral integration and intra-flower variation. To examine the patterns of intra-flower variation in floral traits, including nectar volume, we performed a field study using the zygomorphic flowers of Aconitum japonicum ssp. subcuneatum. We investigated (1) correlations between the sizes of the left and right sepals and petals, (2) variation in floral traits among plants, within plants and within flowers, (3) effects of sexual phases on floral integration variation in floral and nectar traits, and (4) the effect of size and intra-flower variation in traits of the left and right sepals and petals on pollen removal by pollinators. Lateral sepal area, but not lower sepal area, was highly correlated between the left and right sepals. Floral traits were more integrated during the male phase than during the female phase. Nectar standing crop in male-phase flowers correlated with helmet height and lateral and lower sepal area, but in female-phase flowers it only correlated with spur length. While intra-flower variance in lateral sepal area accounted for approximately 10% of the overall variance in these traits, the variance in lower sepal area accounted for 70% of the overall variance. Lateral sepal area had a negative effect on the number of pollen grains remaining after pollinator visits. Low variance in lateral sepals within flowers and measurements of pollen removal suggest that lateral sepals play a more important role in pollen export than the other traits. Left and right sepals may be the targets of selection for symmetry in zygomorphic flowers.

     

Reduced cholecystokinin in the brain of LEC rats with hepatic encephalopathy.

Levels of cholecystokinin (CCK) immunoreactivity and distribution of CCK immunoreactive cells were studied in the cerebral cortex of LEC (Long Evans Cinnamon) rats with hepatic encephalopathy. CCK immunoreactivity in water extract of cerebral cortex of LEC rats with hepatic encephalopathy (n = 7) was 41.5 +/- 2.6 (mean +/- S.E.M. pmol/g wet wt.) and that of LEC rats without encephalopathy (n = 8) was 67.1 +/- 6.9, the difference being significant (P less than 0.01). CCK immunoreactive cells assessed by immunohistochemistry were also markedly decreased in the cortex of LEC rats with hepatic encephalopathy of stage IV. Thus, CCK reduction was observed in the cerebral cortex of LEC rats with hepatic encephalopathy which are provided as a model for analysis of the pathogenesis of acute hepatic encephalopathy.     

Consequences of differences in flowering date on seed production in Heloniopsis orientalis (Liliaceae)

We examined the consequences of differences in flowering date on seed production in the self-compatible herb Heloniopsis orientalis. The number of selfed seeds per fruit, as determined by microsatellite markers, did not depend on when the plant flowered, whereas the number of outcrossed seeds per fruit increased with later flowering dates. Consequently, the selfing rate decreased with later flowering dates. The number of seeds (including both selfed and outcrossed ones) per fruit and the seed?:?ovule ratio increased with later flowering dates. We also examined the effects of pollinators and plant size on seed production. The visitation rate of Diptera did not depend on the flowering season, whereas that of Hymenoptera markedly increased as the flowering season progressed. Diptera stayed longer than Hymenoptera on each plant and flower. Seed production per fruit did not depend on plant size. Thus, the change in selfing rate associated with later flowering dates resulted from the seasonal change in pollinators rather than plant size.     

Cadherin-mediated cell-cell adhesion is perturbed by v-src tyrosine phosphorylation in metastatic fibroblasts

Rat 3Y1 cells acquire metastatic potential when transformed with v-src, and this potential is enhanced by double transformation with v-src and v-fos (Taniguchi, S., T. Kawano, T. Mitsudomi, G. Kimura, and T. Baba. 1986. Jpn. J. Cancer Res. 77:1193-1197). We compared the activity of cadherin cell adhesion molecules of normal 3Y1 cells with that of v-src transformed (SR3Y1) and v-src and v-fos double transformed (fosSR3Y1) 3Y1 cells. These cells expressed similar amounts of P-cadherin, and showed similar rates of cadherin-mediated aggregation under suspended conditions. However, the aggregates or colonies of these cells were morphologically distinct. Normal 3Y1 cells formed compacted aggregates in which cells are firmly connected with each other, whereas the transformed cells were more loosely associated, and could freely migrate out of the colonies. Overexpression of exogenous E-cadherin in these transformed cells had no significant effect on their adhesive properties. We then found that herbimycin A, a tyrosine kinase inhibitor, induced tighter cell-cell associations in the aggregates of the transformed cells. In contrast, vanadate, a tyrosine phosphatase inhibitor, inhibited the cadherin-mediated aggregation of SR3Y1 and fosSR3Y1 cells but had little effect on that of normal 3Y1 cells. These results suggest that v-src-mediated tyrosine phosphorylation perturbs cadherin function directly or indirectly, and the inhibition of tyrosine phosphorylation restores cadherin action to the normal state. We next studied tyrosine phosphorylation on cadherins and the cadherin-associated proteins, catenins. While similar amounts of catenins were expressed in all of these cells, the 98-kD catenin was strongly tyrosine phosphorylated only in SR3Y1 and fosSR3Y1 cells. Cadherins were also weakly tyrosine phosphorylated only in the transformed cells. The tyrosine phosphorylation of these proteins was enhanced by vanadate, and inhibited by herbimycin A. Thus, the tyrosine phosphorylation of the cadherin-catenin system itself might affect its function, causing instable cell-cell adhesion.     

An efficiently extendable and fine-grain parallelised molecular dynamics simulation program: Mid

A new implementation of molecular dynamics simulation is presented. We employed policy-based design to achieve static polymorphism within our simulation programs. This technique provides flexibility and extensibility without additional if-statement branching in the simulation program development. It is shown that policy-based implementation prevents computational performance degradation. We used a fine-grained domain decomposition scheme to parallelise the simulation program. The smaller size decomposition reduces the total amount of inter-processing-core communication and affords good scalability for parallel calculation of short-range forces. The calculation of long-range interactions limits the total scalability. For enhanced performance at high levels of parallelism, the calculation methods for long-range interactions should be improved.     

Day–night fluctuations in floral scent and their effects on reproductive success in <Emphasis Type="Italic">Lilium auratum</Emphasis>

We examined the contribution of diurnal and nocturnal pollination to male and female reproductive success in Lilium auratum. Plants were bagged for either 12 h during the day or at night to allow either only nocturnal or only diurnal visitors to forage throughout the flowering period. We found that there was no significant difference in the seed:ovule ratio among diurnally pollinated, nocturnally pollinated, or control flowers. However, in terms of male reproductive success, it was more advantageous for the plants to be pollinated both diurnally and nocturnally: the numbers of pollen grains remaining in diurnally pollinated or nocturnally pollinated flowers were significantly greater than those in control flowers. The total amount of floral volatiles of L. auratum was significantly higher at night than during the day. The constituents of floral scent of all time series examined were mostly monoterpenoids, many of which serve as attractants for nocturnal hawkmoths. Such nocturnally biased floral scent emission of L. auratum might achieve male reproductive success by attracting nocturnal visitors, which may suggest that the relative contribution of floral scent in this species is biased towards male reproductive success.     

Basement membrane assembly of the integrin α8β1 ligand nephronectin requires Fraser syndrome-associated proteins

Dysfunction of the basement membrane protein QBRICK provokes Fraser syndrome, which results in renal dysmorphogenesis, cryptophthalmos, syndactyly, and dystrophic epidermolysis bullosa through unknown mechanisms. Here, we show that integrin α8β1 binding to basement membranes was significantly impaired in Qbrick-null mice. This impaired integrin α8β1 binding was not a direct consequence of the loss of QBRICK, which itself is a ligand of integrin α8β1, because knock-in mice with a mutation in the integrin-binding site of QBRICK developed normally and do not exhibit any defects in integrin α8β1 binding. Instead, the loss of QBRICK significantly diminished the expression of nephronectin, an integrin α8β1 ligand necessary for renal development. In vivo, nephronectin associated with QBRICK and localized at the sublamina densa region, where QBRICK was also located. Collectively, these findings indicate that QBRICK facilitates the integrin α8β1-dependent interactions of cells with basement membranes by regulating the basement membrane assembly of nephronectin and explain why renal defects occur in Fraser syndrome.