Gentic properties of an R factor carrying resistance to aminolgycoside antibiotics.

R factor Rms 151 is an fi+ R factor and belongs to a incompatibility group FII. It carries the genes governing resistance to various aminoglycoside antibiotics, i.e., kanamycin (KM), lividomycin (LV), gentamicin C complex (GM), and 3',4'-dideoxykanamycin B (DKB), in addition to those governing to tetracycline (TC), chloramphenicol (CM), sulfanilamide (SA), and ampicillin (APC). Electron microscopy observation disclosed that the Rms151 deoxyribonucleic acid was a circular form with length of 31.2 mum. A probable circular genetic map of Rms151 was proposed by genetic and biochemical studies, the genes being in the order of -tet-tra-amp-aad-sul-aph-cml-, in which aad and aph confer resistance to KM.GM.DKB by adenylytransferase or resistance to KM.LV by phosphotransferase, respectively.     

Drug Resistance of Enteric Bacteria

Drug resistance of 3,000 Shigella strains isolated in 1965 were investigated. These strains originated from 10 City Hospitals and 4 Prefectural Health Centers, which are located in different parts of Japan. One hundred and seventy strains which were resistant to 4 drugs, chloramphenicol (CM), tetracycline (TC), dihydrostreptomycin (SM), and sulfanilamide (SA), were selected at random from these stock cultures in this laboratory and the distribution of R factors in these isolates was examined. It was found that the strains all harbored R factors which were capable of transferring drug resistance by usual conjugal process. Among the strains carrying R factors, 85 per cent harbored a single type of R factor and 15 per cent carried two types of R factor in a cell. The latter is called the hetero-R state. Among the strains in the hetero-R state, isolation of strains harboring both R (SM.SA) and R (TC.CM.SM.SA) factors was most frequent. It was found that 25 R (SM.SA) factors isolated from strains in hetero-R had the genetic determinant iR^?, while most of the R (TC.CM.SM.SA) factors isolated from natural sources were iR⁺. When two types of R factor, R (SM.SA) and R (TC.CM.SM.SA) derived from the same host cells, were brought together in a host cell by superinfection with both factors, they were found to exist stably in a host bacterium. These results confirmed the stable existence of both factors in Shigella strains isolated from dysenteric patients.     

Transformation with Vectors Harboring the NEO Selection Marker Induces Germination-Specific Adenylylcyclase Activity in Dictyostelium Cells

Dictyostelium cells express an aggregative adenylylcyclase (ACA), responsible for oscillatory cAMP signaling, and a spore germination-specific adenylylcyclase (ACG). Overexpression of PKA regulatory (R) subunits blocks oscillatory cAMP signaling but increases basal cAMP levels, while neither ACA nor ACG mRNA could be detected. To test whether a novel type of adenylylcyclase (AC) was responsible for cAMP synthesis, dominant-negative PKA-R subunits (PKA-R_M) and control R-subunits (PKA-R_C) were overexpressed in ACA null routants. Both transformations as well as transformation with an unrelated vector, carrying the same NEO^R selection marker, induced an AC activity in growing cells with the biochemical characteristics of ACG. Similar vectors with a different URA selection marker did not increase AC activity. We conclude that the amino-glycoside phosphotransferase encoded by the very commonly used NEO^R selection marker induces ectopic ACG activity in Dictyostelium cells.     

Resistance of Acta2R149C/+ mice to aortic disease is associated with defective release of mutant smooth muscle α-actin from the chaperonin-containing TCP1 folding complex

Pathogenic variants of the gene for smooth muscle α-actin (ACTA2), which encodes smooth muscle (SM) α-actin, predispose to heritable thoracic aortic disease. The ACTA2 variant p.Arg149Cys (R149C) is the most common alteration; however, only 60% of carriers have a dissection or undergo repair of an aneurysm by 70 years of age. A mouse model of ACTA2 p.Arg149Cys was generated using CRISPR/Cas9 technology to determine the etiology of reduced penetrance. Acta2^R149C/+ mice had significantly decreased aortic contraction compared with WT mice but did not form aortic aneurysms or dissections when followed to 24 months, even when hypertension was induced. In vitro motility assays found decreased interaction of mutant SM α-actin filaments with SM myosin. Polymerization studies using total internal reflection fluorescence microscopy showed enhanced nucleation of mutant SM α-actin by formin, which correlated with disorganized and reduced SM α-actin filaments in Acta2^R149C/+ smooth muscle cells (SMCs). However, the most prominent molecular defect was the increased retention of mutant SM α-actin in the chaperonin-containing t-complex polypeptide folding complex, which was associated with reduced levels of mutant compared with WT SM α-actin in Acta2^R149C/+ SMCs. These data indicate that Acta2^R149C/+ mice do not develop thoracic aortic disease despite decreased contraction of aortic segments and disrupted SM α-actin filament formation and function in Acta2^R149C/+ SMCs. Enhanced binding of mutant SM α-actin to chaperonin-containing t-complex polypeptide decreases the mutant actin versus WT monomer levels in Acta2^R149C/+ SMCs, thus minimizing the effect of the mutation on SMC function and potentially preventing aortic disease in the Acta2^R149C/+ mice.     

The Transformation of the Unicellular Alga Chlamydomonas reinhardtii by Electroporation

The cell wall–lacking mutant CW-15 of the unicellular green alga Chlamydomonas reinhardtii was transformed by electroporation using plasmid pCTVHyg, which was constructed with the hygromycin phosphotransferase genehpt as the selective marker and the Tn₅ transposon of Escherichia coli under the control of the virus SV40 early gene promoter. Under optimal conditions (10⁶ mid-exponential cells/ml; electric field strength 1 kV/cm; and pulse length 2 ms), the transformation yielded 10³ Hyg^R transformants per 10⁶ recipient cells. The exogenous DNA integrated into the nuclear genome of Ch. reinhardtii was persistently inherited through more than 350 cell generations. The advantages of this system for the transformation ofCh. reinhardtii with heterologous genes are discussed.     

Scaling relationships for woody tissue respiration in two tropical rain forests

The relationship between gross primary productivity (GPP) and net primary productivity (NPP) is not fully understood. One of the uncertainties relevant to this issue is the magnitude of woody tissue respiration. Although some data exist for temperate and boreal zones, measurements of woody tissue respiration in tropical forests are sparse. We made in situ chamber measurements of woody tissue respiration in two tropical rain forests, one in the Brazilian Amazon (Reserva Jarú) and one in Central Cameroon (Mbalmayo Reserve). We made measurements on a wide range of species at each site and over a range of stem diameters from 0·02 to 1·4 m. The rate of efflux of carbon dioxide (CO₂) from bark at 25 °C, R_t, varied from 0·1 to 5·2 µmol m^?2 s^?1 across the two sites, and the efflux was related to both volume and surface area components of the measured stem sections. The temperature response in R_t was slightly higher at Jarú than at Mbalmayo, with Q₁₀ values of 1·8 (± 0·1 SE) and 1·6 (± 0·1 SE), respectively. A log–log regression showed that R_t was significantly related to stem diameter, D (P < 0·001; r² = 0·58–0·62) and was significantly higher at Mbalmayo than at Jarú (P < 0·001), but that the rate of increase in R_t with stem diameter, D, was similar between sites. At the Mbalmayo site, tree growth measurements made over a 4 month period were used to make two estimates of the maintenance (R_m) and construction (R_c) components of respiration embedded in R_t. The two methods agreed closely, suggesting that R_m was approximately 80% of R_c at this site. R_m could be strongly related to D using a sigmoidal relationship that described both surface area and volume components as sources of respiratory CO₂ (r² = 0·71). This functional model was combined with inventory, growth and climate data for the Mbalmayo site to make a first estimate of annual above‐ground woody tissue respiration, R_A, which was 257 (± 18 SE) g C m^?2 year^?1. This value corresponds to approximately 10% of GPP, slightly lower than that found for another tropical rain forest, but higher than for temperate forests. When combined with data from six other sites in tropical, temperate and boreal settings, a very strong relationship was found between R_A and leaf area index (LAI), and between R_A/GPP and LAI (P < 0·001, r² = 0·98). This indicates that R_A exerts an appreciable constraint on NPP and that this constraint varies closely with LAI across widely differing types of woody vegetation.     

Association of Polymorphisms in the Interleukin 6 Receptor Complex with Obesity and Hyperandrogenism

Objective: Interleukin‐6 (IL‐6), is an inflammatory cytokine that may influence the pathogenesis of obesity and hyperandrogenism. IL‐6 exerts its actions through a heterodimeric receptor consisting of two membrane‐bound glycoproteins: an 80‐kDa IL‐6 binding unit (IL6R‐α) and a 130‐kDa IL‐6 signal transducer (gp130). Genetic variability at these loci might contribute to explain the development of obesity and hyperandrogenism. Research Methods and Procedures: We have evaluated the possible association of several polymorphisms in the IL6R‐α and gp130 genes with obesity and/or hyperandrogenism in a case‐control study involving 143 hyperandrogenic patients and 45 healthy women from Spain. Results: A microsatellite CA‐repeat polymorphism in the IL6R‐α locus was associated with obesity. The frequency of the common 149‐bp allele was markedly increased in obese women compared with controls when considering patients and controls as a whole (0.41 vs. 0.29, χ² = 17.085, p < 0.050). On the other hand, the uncommon Arg148 allele of the Gly148Arg polymorphism in the gp130 gene was more frequent in controls compared with hyperandrogenic patients (0.17 vs. 0.08, χ² = 5.605, p = 0.026). Controls carrying Arg148 alleles had lower 11‐deoxycortisol and 17‐hydroxyprogesterone concentrations, a lower response of androstenedione to 1–24 adrenocorticotropin, and an almost significant decrease in free testosterone levels, suggesting that Arg148 alleles in the gp130 gene have a protective effect against androgen excess and adrenal hyperactivity. Discussion: Polymorphisms in the gp130 and IL6R‐α loci influence hyperandrogenism and obesity, respectively. Our present results further suggest that proinflammatory genotypes are involved in the pathogenesis of these common metabolic disorders.     

Age and growth of the endemic Xingu River stingray Potamotrygon leopoldi validated using fluorescent dyes

Between 2003 and 2005, vertebrae of 151 Xingu River Potamotrygon leopoldi (Potamotrygonidae) (75 males and 76 females) were analysed to derive a growth curve for this species. The disc width (W _D) was significantly different between sexes, with females measuring 149–700 mm W _D and males 109–500 mm W _D. The average percentage error for vertebrae readings of the whole sample was 2·7%. The marginal increment ratio (R _MI) showed an increasing trend with the highest value in November, decreasing from December on. The majority of vertebrae displaying R _MI zero, occurred in September, but the annual periodicity of ring deposition throughout the year was not conclusive. Tetracycline (TCN) injected specimens were held in captivity for 13 months and displayed a fluorescent mark in vertebrae confirming a yearly periodicity of band pair formation with the translucent ring deposited in September–October. The Akaike information criterion (AIC) showed that, among the seven models considered, the best fit was obtained for the von Bertalanffy modified with W ₀ (where W ₀ = W _D at birth) for both sexes. Growth parameters for females were: W ₀ = 149 mm; W _∞ = 763·06 mm; k = 0·12 year^{– 1}, whereas for males: W ₀ = 109 mm; W _∞ = 536·4 and k = 0·22 year^?1. Maximal ages were 7·2 years in males and 14·3 years in females. The species shows sexual dimorphism expressed in the growth pattern, size at maturity, longevity and asymptotic sizes. Concern for sustainability is raised due to the construction of the Belo Monte Hydroelectric Power Plant (2015 and 2016) in the State of Pará causing changes to the habitat of this species, which is endemic to the Xingu River and two of its tributaries.     

Comparative hydrocarbon utilization by hydrophobic and hydrophilic variants of Pseudomonas aeruginosa

Aims: To investigate hydrocarbon degradation by hydrophobic, hydrophilic and parental strains of Pseudomonas aeruginosa. Methods and Results: Partitioning of hydrocarbon‐degrading P. aeruginosa strain in a solvent/aqueous system yielded hydrophobic and hydrophilic fractions. Exhaustive partitioning of aqueous‐phase cells yielded the hydrophilic variants (L), while sequential fractionation of the hydrophobic phase cells yielded successive fractions exhibiting increasing cell‐surface hydrophobicity (CSH). In hydrocarbon adherence assays (bacterial attachment to hydrocarbon), L had a value of 20%, which increased from 61·7% in first hydrophobic fraction (H₁) to 72·2% in the third (H₃). Crude oil degradation by L was 70%, but increased from 82% in H₁ to 93% in H₃. L variant produced most exopolysaccharides and reduced surface tension from about 73 to 49 mN m^?1. Rhamnolipid production was highest in L, but was not detected in all crude oil cultures. Conclusions: Hydrophobic subpopulations of hydrocarbon‐degrading P. aeruginosa exhibited greater hydrocarbon‐utilizing ability than hydrophilic ones, or the parental strain. Significance and Impact of the Study: Results demonstrate that a population of P. aeruginosa consists of cells with different CSH which affect hydrocarbon utilization. This potentially provides the population with the capacity to utilize different hydrophobic substrates found in petroleum. Judicious selection of such hydrophobic subpopulations can enhance hydrocarbon pollution bioremediation.     

Kinetic characterization of the double mutant R148A/E182S of glycogen phosphorylase kinase catalytic subunit: the role of the activation loop

Many protein kinases are activated by phosphorylation in a highly conserved region of their catalytic subunit, termed activation loop. Phosphorylase kinase is constitutively active without the requirement for phosphorylation of residues in the activation loop. The residue which plays an analogous role to the phosphorylatable residues in other protein kinases is Glu182, which makes contacts to a highly conserved Arg148. In turn, Arg148 adjacent to the catalytic Asp149, enabling information to be transmitted from the activation loop to the catalytic machinery. The double mutant R148A/E182S has been kinetically characterized. The mutation resulted in an approximate 16- to 22-fold decrease in the k _cat/K _m value of the enzyme. The kinetic data, discussed in the light of the structural data from previously determined complexes of the enzyme, lead to the suggestion that the activation loop has a major role in substrate binding but also in correct orientation of the groups participating in catalysis.     

Regeneration of fertile transgenic indica (group 1) rice plants following microprojectile transformation of embryogenic suspension culture cells

Regenerable embryogenic suspensions of elite Indica (group 1) rice varieties IR24, IR64, IR72 and an advanced Indica rice breeding line IR57311-95-2-3 were established within 6–8 weeks from 3–4 week old calli derived from mature seeds. Transgenic rice plants were obtained by introducing a plasmid carrying genes encoding hygromycin phosphotransferase (hph, conferring resistance to hygromycin B) and ß-glucuronidase (uidA), both driven by the CaMV 35S promoter, via particle bombardment of embryogenic suspensions. The effect of osmotic conditioning on transformation was evaluated. Regenerated plants were resistant to hygromycin B and expressed the uidA (GUS) gene. The growth of mother plants (R₀) was normal and seeds were produced. Southern blot analysis of R₀ and R₁ plants showed that hygromycin resistant plants contained intact hph genes that were inherited in a Mendelian fashion. A protocol for a simple, efficient, repeatable, genotype- and environment-independent Indica rice transformation system is described.Abbreviations 2,4-D 2,4-dichlorophenoxy acetic acid - NAA -naphthalene acetic acid - kb kilobase - GUS ß-glucuronidase - hph hygromycin B phosphotransferase     

Chiral Metal Complexes. 27. Stereoselectivity in the synthesis and reaction of coordinated aminomalonic acid derivatives

The synthesis is reported of a series of ternary cationic complexes of general form [Co(R,Rpicchxn)(ARMA)⁺ (where picchxn is the N₄ tetradentate N,N′-di(2-picolyl)-1,2-diaminocyclohexane and ARMA is a bidentate α-substituted-α-aminomalonate dianion). The aminomalonic acid (NH₂· C(COOH)₂·R) derivatives investigated have R = -CH₃ (AMMAH₂), -CH₂·CH₃ (AEMAH₂), -CH₂· CH₂·CH₃ (APMAH₂), -CH₂·(CH₂)₂·CH₃ (ABuTMAH₂, -CH₂·C₆H₅ (ABMAH₂), -CH₂·(p-C₆H₄)· C(CH₃)₃ (ABuBMAH₂) and -CH₂·C₁₀H₇ (ANMAH₂). The isomeric species in the complex products have been separated using cation exchange chromatography and each isomer has been characterized using NMR and circular dichroism techniques. In each synthesis the major isomeric product obtained has a Λ-β₁ topology. However, where ARMAH₂ possesses a lengthy alkyl sidechain trace amounts of Δ-α-[Co(R,R-picchxn)(ARMA)]⁺ isomers have been observed during the synthetic reactions. This unusual isomeric form readily undergoes inversion of its absolute configuration in DMSO solution to yield the more thermodynamically stable Λ-β₁-[Co(R,R-picchxn()R-ARMA)]⁺ species stereospecifically.In the case of Λ-β₁-[Co(R,R,-pichxn)(S-APMA)]ClO₄·2NaClO₄·5H₂O the crystal structure has been determined. The compound crystallises in the orthorhombic space group P2₁2₁2₁, with a = 10.056(3),b = 16.475(7),c = 23.370(7)Å and Z = 4. The structure was refined to R = 0.079 for 4460 non-zero reflexions, and confirms the absolute configuration of each chiral centre to be consistent with the NMR and circular dichroism interpretations.The decar☐ylation of these chelate ARMAH₂ derivatives under acid conditions leads to corresponding complexes containing mixtures of coordinated R-andS-α-aminoacids in various ratios. This ratio has been determined in each case, and factors which may influence the degree of chiral induction observed are discussed.     

EVALUATION OF COMPETITIVE ABILITY OF STAURASTRUM LUETKEMUELLERII (CHLOROPHYCEAE) AND MICROCYSTIS AERUGINOSA (CYANOPHYCEAE) UNDER P LIMITATION1

The desmid Staurastrum luetkemuellerii Donat et Ruttner and the cyanobacterium Microcystis aeruginosa Kütz. showed pronounced differences in chemical composition and ability to maintain P fluxes. The cellular P:C ratio (Q_p) and the surplus P:C ratio (Q_sp) were higher in M. aeruginosa, indicating a lower yield of biomass C per unit of P. The subsistence quota (Q_p) was 1.85 μg P·mg C^?1in S. luetkemuellerii and 6.09 μg P·mg C^?1in M. aeruginosa, whereas the respective Q_p of P saturnted organisms (Q_s) were 43 and 63 μg P·mg C^?1. These stores could support four divisions in S. luetkemuellerii and three divisions in M. aeruginosa, which suggests that the former exhibited highest storage capacity (Q_s/Q₀). M. aeruginosa showed a tenfold higher activity of alkaline phosphatase than S. luetkemuellerii when P starved. The optimum N:P ratio (by weight) was 5 in S. luetkemuellerii and 7 in M. aeruginosa. The initial uptake of P_i pulses in the organisms was not inhibited by rapid (<1 h) internal feedback mechanisms and the short term uptake rote could be expressed solely as a function of ambient P_i. The maximum cellular C-based uptake rate (V_m) in P starved M. aeruginosa was up to 50 times higher than that of S. luetkemuellerii. It decreased with increasing growth rate (P status) in the former species and remained fairly constant in the latter. The corresponding cellular P-based value (U_m= V_m/Q_p) decreased with growth rate in both species and was about 10 times higher in P started M. aeruginosa than in S. luetkemuellerii. The average half saturation constant for uptake (K_m) was equal for both species (22 μg P·L^?1) and varied with the P status. S. luetkemuellerii exhibited shifts in the uptake rate of P_i that were characterized by increased affinity (U^m/K^m) at low P_i, concentrations (<4 μg P·L^?1) compared to that at higher concentrations. The species thus was well adapted to uptake at low ambient P_i, but M. aeruginosa was superior in P_i uptake under steady state and transient conditions when the growth rate was lower than 0.75 d^?1. Moreover, M. aeruginosa was favored by pulsed addition of P_i. M. aeruginosa relpased P_i at a higher rate than S. luetkemuellerii. Leakage of P_i from the cells caused C-shaped μ vs. P_i curves. Therefore, no unique K_s for growth could be estimated. The maximum growth rate (μ_m) (23° C) was 0.94 d^?1for S. luetkemuellerii and 0.81 d^?1for M. aeruginosa. The steady state concentration of P_i (P*) was lower in M. aeruginosa than in S. luetkemuellerii at medium growth rates. The concentration of P_i at which the uptake and release of P_i was equal (P_c was, however, lower in S. luetkemuellerii.     

Recombination Between a Thermosensitive Kanamycin Resistance Factor and a Nonthermosensitive Multiple-Drug Resistance Factor

The thermosensitive kanamycin (KM) resistance factor, R(KM)(t), and a nonthermosensitive multiple-drug resistance factor, R(100), were simultaneously introduced into Escherichia coli and Salmonella typhimurium. The temperature sensitivity of both R factors remained unchanged as long as they replicated independently. Under certain conditions, however, a new thermosensitive R factor harboring resistance markers for kanamycin, streptomycin (SM), and sulfanilamide (SA) was obtained by recombination between the R(KM)(t) and R(100) factors. R factors carrying resistance markers for KM and SA, or for SM and SA, were obtained from the recombinant R(KM SA SM)(t) by spontaneous segregation. Though the R(100) factor has been known as an fi(+) (positive for F-mediated fertility inhibition of its host) type and it does not restrict any coexisting phages, the thermosensitive recombinants of R(100) with R(KM)(t) and their segregants were found to be fi(-) and to restrict the replication of all T-even phages, as does the R(KM)(t) factor. Double infection immunity was not observed between the R(KM)(t) and R(100) factors.     

Bioenergetics of juvenile whitespotted bamboo shark Chiloscyllium plagiosum [Anonymous (Bennett)]

This study establishes the bioenergetics budget of juvenile whitespotted bamboo shark Chiloscyllium plagiosum by estimating the standard metabolic rate (R_S), measuring the effect of body size and temperature on the R_S, and identifying the specific dynamic action (R_SDA) magnitude and duration of that action in juvenile whitespotted bamboo sharks. The mean ±s .d . (R_S) of six fish (500–620 g) measured in a circular closed respirometry system was 30·21 ± 5·68 mg O₂ kg^?1 h^?1 at 18° C and 70·38 ± 14·81 mg O₂ kg^?1 h^?1 at 28° C, respectively. There were no significant differences in R_S between day and night at either 18 or 28° C (t‐test, P > 0·05). The mean ±s .d . Q₁₀ for 18–28° C was 2·32 ± 0·06 (n = 6). The amount of oxygen consumed per hour changed predictably with body mass (M; 295–750 g) following the relationship: (n = 40, r²= 0·92, P < 0·05). The mean magnitude of R_SDA was 95·28 ± 17·55 mg O₂ kg^?1 h^?1. The amount of gross ingested energy (E_I) expended as R_SDA ranged from 6·32 to 12·78% with a mean ±s .d . of 8·01 ± 0·03%. The duration of the R_SDA effect was 122 h. The energy content of juvenile whitespotted bamboo shark, squid and faeces determined by bomb calorimeter were 19·51, 20·3 and 18·62 kJ g dry mass^?1. A mean bioenergetic budget for juvenile whitespotted bamboo sharks fed with squid at 18° C was 100C = 29·5G + 31·9R_S+ 28·2R_SDA+ 6·7F + 2·1E + 1·6U, where C = consumption, G = growth, F = egestion, E = excretion and U = unaccounted energy.     

Reproductive biology of female striped marlin Kajikia audax in the western Pacific Ocean

Length and mass data for 1260 (536 females, 683 males, 41 sex unknown) striped marlin Kajikia audax were collected at the fish markets of Tungkang, Singkang and Nanfangao from July 2004 to September 2010. Of these samples, 534 gonads (236 females and 298 males) ranging from 95 to 206 cm in eye‐to‐fork length (L _EF ) and 8 to 88 kg in round mass (M _R), were collected. Chi‐square tests indicated sex ratios were homogeneous among months in 2004 and 2006–2008, but not in 2005, 2009 and 2010; and there were significant differences in sex ratio by size. The overall sex ratio (R _S ) differed significantly from the expected 0·5. Kajikia audax are sexually dimorphic and the proportions of females increased with size between 140 and 210 cm L _EF . Reproductive activity was assessed using a gonado‐somatic index (I _G ), external appearance of the gonads and histological examination and results indicated that the spawning season occurred from April to August with a peak in June to July. Based on histological observations and the distribution of oocyte diameters, K. audax are multiple spawners and their oocytes develop asynchronously. The estimated length‐at‐50% maturity (L _EF50 ) was c . 181 cm (c . 4·8 years of age) for females. The proportion of reproductively active females in the spawning season with ovaries containing postovulatory follicles (0·27) indicated that they spawned every 3·7 days on average. The hydrated oocyte method estimated mean ± S.D. batch fecundity (F _B ) to be 4·4 ± 2·02 million eggs; average relative fecundity was 53·6 ± 13·9 oocytes g^?1 M _R; and the average annual fecundity was 181·3 ± 48·3 million eggs. The parameters estimated in this study are key information for stock assessments of K. audax in the north‐western and central Pacific and will contribute to the conservation, management and sustainable yield of this species.     

Optical resolution by preferential crystallization of (2RS,3SR)-2-amino-3-chlorobutanoic acid hydrochloride

(2RS,3SR)-2-Amino-3-chlorobutanoic acid hydrochloride [(2RS,3SR)-ACB · HCl] was found to exist as a conglomerate based on the melting point, infrared spectrum, and solubility. Optical resolution by preferential crystallization of (2RS,3SR)-ACB · HCl was achieved to yield both (2R,3S)- and (2S,3R)-ACB · HCl of 80–100% optical purities. The obtained (2R,3S)- and (2S,3R)-ACB · HCl were recrystallized, taking into account the solubility of (2RS,3SR)-ACB · HCl, to give efficiently optically pure (2R,3S)- and (2S,3R)-ACB · HCl. Treatment of the purified (2R,3S)- and (2S,3R)-ACB · HCl with triethylamine gave optically pure (2R,3S)- and (2S,3R)-2-amino-3-chlorobutanoic acid, respectively. Chirality 9:656–660, 1997. © 1997 Wiley-Liss, Inc.     

Standard metabolism and growth dynamics of laboratory‐reared larvae of Sardina pilchardus

This study provides the first measurements of the standard respiration rate (R_S) and growth dynamics of European sardine Sardina pilchardus larvae reared in the laboratory. At 15° C, the relationship between R_S (µl O₂ individual^?1 h^?1) and larval dry mass (M_D, µg) was equal to: R_S = 0·0057(±0·0007, ± s.e.)·M_D^{0·8835(±0·0268)}, (8–11% M_D day^?1). Interindividual differences in R_S were not related to interindividual differences in growth rate or somatic (Fulton's condition factor) or biochemical‐based condition (RNA:DNA).     

Effects of ozone on membrane permeability and ultrastructure in Pseudomonas aeruginosa

Aims: To examine the mechanism of ozone‐induced damage to cytoplasmic membrane and cell ultrastructure of Pseudomonas aeruginosa ATCC27853. Methods and Results: Cell suspensions of Ps. aeruginosa ATCC27853 were treated with ozonated water. The leakages of cellular potassium (K⁺), magnesium (Mg²⁺) and adenosine triphosphate (ATP), determined by inductively coupled plasma/mass spectrometry (ICP/MS) and a commercial bioluminescence assay kit, were to assess ozone‐induced damage to the cytoplasmic membrane. Maximum leakages of K⁺ and Mg²⁺ were attained, respectively, at 0·53 mg l^?1 ozone after 0·5 and 2 min with >99% inactivation of culturable bacteria, while that of ATP was achieved at 0·67 mg l^?1 ozone after 1 min. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed that treated cells retained intact shapes and cytoplasm agglutinations and vacuoles occurred. Conclusions: Ozone inactivates Ps. aeruginosa ATCC27853 by the combined results of increased cytoplasmic membrane permeability and cytoplasm coagulation, rather than by severe membrane disruption and cell lysis. Significance and Impact of the Study: Pseudomonas aeruginosa is a common water‐related pathogen. These insights into the leakage of cytoplasmic components and ultrastructural changes provide evidence for the mechanisms of ozone‐mediated inactivation.