Adaptations for feeding on rock surfaces and sandy sediment by the fiddler crabs (Brachyura: Ocypodidae) Uca tetragonon(Herbst, 1790) and Uca vocans(Linnaeus, 1758)

Two species of fiddler crab, Uca tetragonon(Herbst, 1790) and Uca vocans(Linnaeus, 1758), which belong to the subgenus Gelasimus, dwell on rocky shores and muddy–sandy tidal flats, respectively, in Phuket Is., Thailand. We investigated their feeding ecology in relation to the morphology of their feeding organs: minor food-handling chelipeds and maxillipeds. U. tetragononfed chiefly on rocks covered by filamentous green algae. U. vocansfed on the emerged sand and in shallow water along the shoreline and in pools. While feeding, both crabs made sand pellets beneath their mouthparts and discarded them, indicating that they divided the matter scooped up with their minor chelipeds into edible and inedible fractions by using the maxillipeds in the water passing through their buccal cavity. The morphology of maxillipeds hardly differed between the two species, which means that both species are flotation-feeders. The morphology of their minor chelipeds, however, differed: the tips of the dactyl and pollex were flat in U. tetragononand pointed in U. vocans.When the minor cheliped was closed, U. tetragononhad a hemispherical space in the distal one-fourth of the gape, which was closed by the framing keratin layers and a few setae of the dactyl and pollex. On the other hand, U. vocanshad an ellipsoidal space in the distal half of the gape. We consider these morphological characters to be adaptations to the different feeding substrates for retaining more food-laden sediment. We discuss the role of the setae on the minor chelipeds on the basis of the morphological differences between populations of U. tetragononin Phuket Is. and East Africa where the crab inhabits muddy–sandy tidal flats.     

Characterization of translucent segments observed in an smbA mutant of Escherichia coli

Abstract The smbA gene of Escherichia coli is essential for cell proliferation. The smbA2 mutant shows cold-sensitive colony formation at 22°C. A novel morphological phenotype, formation of a translucent segment at midcell or at a cell pole, was observed by phase-contrastt microscopy at a high frequency in the smbA2 mutant cells incubated in L medium lacking NaCl at 22°C, but not observed in L medium containing 1% NaCl or 20% sucrose at the same temperature. No translucent segment was observed in the wild-type cells in any of the media used. Electron microscopic observation revealed that the translucent segments resulted from the enlargement of a periplasmic space by separation of the inner membrane from the peptidoglycan layer and the outer membrane.     

Chloroplast genome evolution in the genus Avena

The genus Avena contains five different chloroplast genomes, I-V. A physical map of chloroplast (ct) DNA of Avena sativa (type I chloroplast genome) was constructed using three restriction endonucleases, PstI, SalI and SmaI. This genome is ca. 135.5 kbp in size, and contains two inverted repeats of ca. 22.5 kbp each, separated by a large (ca. 79.0 kbp) and small (ca. 12.5 kbp) single copy region. The rbcL gene which codes for the large subunit of ribulose 1,5-bisphosphate carboxylase, was located in the map. Restriction fragment patterns of all five chloroplast genomes were compared, and among them five fragment size and five restriction site mutations were disclosed. Four site mutations were found in two or more chloroplast genomes, the other site and five fragment size mutations were specific to one or another of the chloroplast genomes. A dendrogram showing phylogenetic relationships among the five chloroplast genomes, based on the distribution of the common and specific mutations among them, indicates that chloroplast genome divergence characterized by three restriction site mutations occurred first between two diploid groups, each carrying A and C genome (nuclear), respectively, followed by further speciation in each group.     

Determination of the primary structure of Paim II, an alpha-amylase inhibitor from Streptomyces coruchorushii, by high-performance tandem mass spectrometry

This study indicates one of the advantages of tandem mass spectrometry; the primary structures of proteins with little structural difference can be determined by using tandem mass spectrometry without prior purification of each component. The primary structure of Paim II, a protein alpha-amylase inhibitor from Streptomyces coruchorushii, was determined by using tandem mass spectrometry. Paim II consists of two component proteins with ragged N-terminus, and was sequenced on the basis of the structure of Paim I, an analogous alpha-amylase inhibitor from the same natural origin.     

The occurrence of a premature form of egg-specific protein in vitellogenic follicles ofBombyx mori

Summary Analysis of yolk proteins of the silkworm,Bombyx mori, by SDS-polyacrylamide gel electrophoresis and immunoblotting showed that there was a developmental change in subunit composition of egg-specific protein; egg-specific protein consisting of 72 kDa subunits alone (premature form) was found in vitellogenic follicles, whereas the protein in mature eggs was composed of 72 kDa and 64 kDa subunits (mature form). The premature form of egg-specific protein was purified from young ovaries to homogeneity using a high performance liquid chromatography system. The purified protein had an apparent molecular mass of 225 kDa which could not be distinguished from that of the mature form. By circular dichroism analysis, both egg-specific proteins were estimated to have about 30% -helix and 20% -sheet, but the mature form showed a relatively rigid conformation in the aromatic region. The premature egg-specific protein purified from vitellogenic ovaries, consisted of three 72 kDa subunits, whereas mature egg-specific protein was composed of two 72 kDa subunits and one 64 kDa subunit. All of these subunits showed the same immunoreactivity towards antiserum raised against the mature form. An identical NH₂-terminal amino acid sequence was found in both 72 kDa polypeptides and 64 kDa polypeptide for the initial 10 amino acids.Abbreviations SDS sodium dodecyl sulfate - PMSF phenylmethylsulfonyl fluoride - PAGE polyacrylamide gel electrophoresis - HPLC high performance liquid chromatography - ESP egg-specific protein - Vtn vitellin     

Regulation of breathing movements in fetal sheep by prostaglandin E2

In fetal sheep, plasma prostaglandin (PG) E2 concentrations are high, and fetal breathing movements (FBM) occur intermittently, primarily during low-voltage fast electrocortical activity (LVFA). There is evidence suggesting that prostaglandins, specifically PGE2, may regulate FBM. To define the physiological role of PGE2 in regulation of FBM, we infused meclofenamate (0.9 mg X kg-1 X h-1), a prostaglandin synthetase inhibitor, into six fetal sheep to suppress endogenous prostaglandin production. Afterward, PGE2 was added in mean doses of 9, 18, 36, and 90 ng X kg-1 X min-1. Meclofenamate decreased PGE2 concentrations and increased FBM, especially during high-voltage slow electrocortical activity (HVSA). Addition of PGE2 reversed the effects of meclofenamate, increasing PGE2 concentrations and decreasing FBM, especially during HVSA. The response to PGE2 was dose dependent; the overall incidence of FBM and incidences of FBM during HVSA and LVFA were inversely correlated with both the infused PGE2 dose and the mean PGE2 concentration. At higher doses of PGE2, FBM occurred intermittently and only during LVFA; thus PGE2 infusion restored the physiological pattern of FBM. These results indicate that PGE2 regulates FBM by inhibiting FBM during HVSA.     

On periodic responses of a mathematical neuron model

The periodic responses of a mathematical neuron model, when periodically varying input stimuli are applied to the model, are investigated. An explicit representation of periodic responses is obtained. It is shown that a periodic response as a 0–1 string is a uniform string. That is, the 1's of the 0–1 string are distributed uniformly in the string.     

Mucociliary clearance in chronic sinusitis: related human nasal clearance and in vitro bullfrog palate clearance

Nasal mucociliary clearance was measured in both healthy subjects and patients with chronic sinusitis using saccharin granule technique. Nasal mucociliary transit time (ST) was significantly slower in the patients with chronic sinusitis compared with that in controls (p less than 0.005). Nasal mucus collected from each nasal cavity was used for in vitro bullfrog palate clearance studies and compared to the in vivo nasal ST. Mucociliary clearance rate (MTR) on frog palate was 12.5 +/- 2.5 mm/min in the mucus from control subjects, 6.1 +/- 1.5 mm/min in the mucus from the patients. The difference was statistically significant (p less than 0.005). The MTR on frog palate in the patients whose nasal ST was within normal range was significantly slower than that in controls (p less than 0.005), but not significantly different from that in the patients whose nasal ST was over the normal range. These results suggest that the nasal mucous properties which decreased the mucociliary clearance on frog palate did not contribute to the mucociliary clearance of the patients who had a normal one. No significant correlation existed between MTR on frog palate and nasal ST in both control and chronic sinusitis. In chronic sinusitis patients, decelerated nasal ST was recovered significantly by normal saline nebulization compared with the value before the nebulization (p less than 0.01). None of the significant change of ST was observed in control before and after the nebulization.     

Examination of the influences of density pressure on the pattern of adult emergence with reference to the azuki bean weevil,Callosobruchus chinensis

Summary The effect of competition pressure on the sequential pattern of adult emergence was studied by using the experimental population of the azuki bean weevil. The density and pattern of emergence curves of the parental adult induced the changes in the shape of emergence curve of the progeny as well as the number of progeny individuals. In order to explain these changes, a simple mathematical model which has two independent variables, the population density and the capacity of environment, was introduced. The model generated basically similar patterns of emergene curves as observed in the present experiments. This means that the model displayed well the competition pressure which differentially acted upon early-born and late-born individuals in the populations being at different densities and which were differentially received by individual progeny according to the sequential distributions of parents. This different severity of competition pressure resulted in the difference of time when the pressure compelled influences on the sequential distribution of adult emergence. Therefore, early developed individuals may have good chance to survive, but the competition pressure works as a factor modifying their fundamental superiority, especially in the scramble type of competition. Intense crowding of the azuki bean weevil gave rise to the scramble type of competition in the relation between the numbers of adults emerged in two successive generations. When parental emergence concentrated in a short term and at high density, the competition becomes intense, resulting in the inferiority of early developed individuals, in the decrease in number at the next generation and in the increase of duration for emergence.