Catalytic properties of aminoacylase of strain <Emphasis Type="Italic">Rhodococcus armeniensis</Emphasis> AM6.1

Studies of substrate specificity revealed that the D-aminoacylase of Rhodococcus armeniensis AM6.1 strain exhibits absolute stereospecificity to the D-stereoisomers of N-acetyl-amino acids. The enzyme is the most active reacted with N-acetyl-D-methionine, as well as with aromatic and hydrophobic N-acetylamino acids and interacts weakly with the basic substrates. It is practically not reacted with acidic and hydrophilic N-acetyl-amino acids. Michaelis constants (K_m) and maximum reaction velocities (V_max) were calculated, using linear regression analysis, for the following substrates: N-acetyl-D-methionine, N-acetyl-D-alanine, N-acetyl-D-phenylalanine, N-acetyl-D-tyrosine, N-acetyl-D-valine, N-acetyl-D-oxyvaline, N-acetyl- D-leucine. Substrate inhibition of D-aminoacylase was displayed with N-acetyl-D-leucine (K_s = 35.5 ± 28.3 mM) and N-acetyl-DL-tyrosine (K_s = 15.8 ± 4.5 mM). Competitive inhibition of the enzyme with product–acetic acid (K_i = 104.7 ± 21.7 mM, K_m = 2.5 ± 0.5 mM, V_max = 25.1 ± 1.5 U/mg) was observed.     

Kinetic Analyses of the Substrate Inhibition of <Emphasis Type="Italic">Paramecium</Emphasis> Arginine Kinase

Paramecium tetraurelia expresses four types of arginine kinase (AK1–AK4). In a previous study, we showed that AK3 is characterized by typical arginine substrate inhibition, where enzymatic activity markedly decreases near a concentration of 1 mM of arginine substrate. This is in sharp contrast to the three other AK types, which obey the Michaelis–Menten reaction curve. Since cellular arginine concentration in another ciliate Tetrahymena is estimated to be 3–15 mM in vivo, Paramecium AK3 likely functions in conditions that are strongly affected by substrate inhibition. The purpose of this work is to find some novel aspect on the kinetic mechanism of the substrate inhibition of Paramecium AK3 enzyme. Substrate inhibition kinetics for AK3 were analyzed using three models and their validity were evaluated with three static parameters (R², AICc, and Sy.x). The most accurate model indicated that not only ES but also the SES complex reacts to form products, the latter being the complex with two substrates in the active center. The maximum reaction rate for the SES complex, V_max^SES?=?30.4 µmol Pi/min/mg protein, was one-eighth of the ES complex, V_max^ES?=?241.7. The dissociation constant for the SES complex (K_i^SES: 0.34 mM) was two times smaller than that of the ES complex (K_s^ES: 0.61 mM), suggesting that after the primary binding of the arginine substrate (ES complex formation), the binding of a second arginine to the secondarily induced inhibitory site is accelerated to form an SES complex with a lower V_max^SES. The same kinetics were used for the S79A, S80A, and V81A mutants. The results indicate that the S79 residue is significantly involved in the process of binding the second arginine substrate. Herein, the K_i^SES value was ten times (3.62 mM) the value for the wild-type (0.34 mM), weakening substrate inhibition. In contrast, V_max^ES and V_max^SES values for the mutants decreased by one-third, except for the V_max^SES of the S79A mutant, which had a value that was comparable with the value for the wild-type.     

Evidences and magnitude of nighttime transpiration derived from <Emphasis Type="Italic">Populus euphratica</Emphasis> in the extreme arid region of China

Extensive research has found that nighttime transpiration (E _n) is positively correlated to the vapour pressure deficit (VPD), that suggested E _n was highest during the night under high temperatures and low humidity along with high soil water availability, typically for the riparian forest in the extreme arid region of China. This study used the heat ratio method to measure sap velocity (V _s) for mature and saplings Populus euphratica Oliv., and then E _n was conservatively calculated as total nocturnal sap flow (F _s, the product of V _s and sapwood area A _s) between 01:00 to 06:00. A gas exchange system was used to measure the leaf transpiration rate (T _r) and stomatal conductance (g _s) of saplings. For mature trees, nighttime V _s was extensive and logarithmic correlated to VPD (similar to daytime). For saplings, g _s and T _r was extensive in different months, and also a strong logarithmic relationship was found between V _s and VPD for both daytime and nighttime periods. Both of stem sap flow and leaf gas exchange suggusted the occurrence of E _n, whether mature or sapling trees. E _n contribution to daily transpiration (E _d) was high just as expected for P. euphratica, which was confirmed by proportional E _n to E _d (E _n/E _d) means taken in 2012 (24.99%) and 2013 (34.08%). Compared to mature trees, E _n/E _d of saplings in 2013 was lower with means of 12.06%, that supported further by the shorter duration times and less T _r,n (16.64%) and g _s,n (26.45%) of leaf, suggesting that E _n magnitude is associated to individual the tree size, that effect to stored water of individual trees, although this hypothesis requires further research.     

Selenate reduction rates and kinetics across depth in littoral sediment of the Salton Sea,California

To predict selenium cycling in sediments, it is crucial to identify and quantify the processes leading to selenium sequestration in sediments. More specifically, it is essential to obtain environmentally-relevant kinetic parameters for selenium reduction and information on how they spatially vary in sediments. The Salton Sea (California, USA) is an ideal model system to examine selenium processes in sediments due to its semi-enclosed conditions and increasing selenium concentration over the last century. Selenium enters the Salton Sea mainly as selenate and might be sequestered in the sediment through microbial reduction. To determine the potential selenium sequestration of Salton Sea littoral sediments and which sediment properties are controlling selenate reduction kinetics, we determined the centimeter-scale vertical distribution of potential selenate reduction rates and apparent kinetic parameters (maximum selenate reduction rates, V_max, and selenate half-saturation concentration, K_m) using flow-through reactor (FTR) experiments. We compared sediments from two littoral sites (South and North) and four depth intervals (0–2, 2–4, 4–6 and 6–8 cm). Furthermore, we characterized the selenium fractions in the sediment recovered from the FTR experiments to identify the processes leading to the sequestration of selenium. Our results reveal higher potential for selenium reduction and sequestration in the topmost sediment (0–2 cm) suggesting that microorganisms inhabiting surface sediment are well adapted to reduce selenate entering the Salton Sea. As apparent K_m values (103–2144 µM) exceed the average selenium concentration in the overlying water (6–25 nM), in situ selenate reduction is limited by the low availability of selenate and the resident selenate-reducing microorganisms operate well below their V_max (11 and 43 nmol cm^?3 h^?1). Selenium speciation after FTR experiments confirms the primary sequestration of reduced biomass-associated and elemental selenium (68–99% of total selenium) in the sediment. Further, the absence of correlation between the tested sediment physical (porosity, bulk density, clay content), chemical (C_org, N_tot, total selenium content) and biological characteristics (abundance of culturable selenate-reducers) with the kinetic parameters of selenate reduction indicates that these sediment characteristics cannot be used as predictors of apparent V_max or K_m. Conclusively, microbial selenate reduction is an important, if not the primary process, leading to the sequestration of reduced selenium in the Salton Sea sediments and making the surficial Salton Sea sediments an important selenium sink.     

Gas exchanges of an endangered species <Emphasis Type="Italic">Syringa pinnatifolia</Emphasis> and a widespread congener <Emphasis Type="Italic">S. oblata</Emphasis>

Net photosynthetic rate (P_N), transpiration rate (E), water use efficiency (WUE), stomatal conductance (g_s), and stomatal limitation (L_s) were investigated in two Syringa species. The saturation irradiance (SI) was 400 µmol m^-2s^-1 for S. pinnatifolia and 1 700 µmol m^-2s^-1 for S. oblata. Compared with S. oblata, S. pinnatifolia had extremely low g _s . Unlike S. oblata, the maximal photosynthetic rate (P_max) in S. pinnatifoliaoccurred around 08:00 and then fell down, indicating this species was sensitive to higher temperature and high photosynthetic photon flux density. However, such phenomenon was interrupted by the leaf development rhythms before summer. A relatively lower P_N together with a lower leaf area and shoot growth showed the capacity for carbon assimilation was poorer in S. pinnatifolia.     

<Emphasis Type="Italic">Lsi1</Emphasis>-regulated Cd uptake and phytohormones accumulation in rice seedlings in presence of Si

Silicon (Si) is known for its role in regulating the response of plants to imposed abiotic stresses. Since the stresses generally hinder production of a crop, such as rice, the exploration of the biochemistry and plant physiology relating to the function is of interest. Indeed, recently, there were reports on the function of Lsi1 in regulating the tolerance of rice to cadmium (Cd) stress. This study compared the kinetics of the Cd uptakes in Lemont wild type rice and its transgenic lines exposed to Cd with or without exogenous Si supply. At the same time, changes on the endogenous phytohormones and growth of the rice seedlings were monitored. Genetically, Lsi1 overexpression was found to downregulate K_m and V_max of Cd uptake kinetics in the plants under Cd stress, especially in the presence of Si. On the other hand, Lsi1 RNAi upregulated K_m and V_max regardless whether Si was present or not. It implied that Lsi1 could be capable of regulating Si as well as Cd transports. Under Cd stress, addition of Si reduced the Cd uptake of the rice lines in the order of Lsi1-overexpression line?>?Lemont?>?Lsi1-RNAi line. In addition, it also affected the chlorophyll biosynthesis and dry mass accumulation of the rice plants under Cd stress. Analyses on phytohormones including IAA, GA₃, JA, SA and ABA, as well as physiological functions, of the seedlings further verified the active involvement of Lsi1 in the complex defense system of the plants against Cd stress.     

Calponin-like protein from mussel smooth muscle is a competitive inhibitor of actomyosin ATPase

The goal of this work was to elucidate the mechanism of inhibition of the actin-activated ATPase of myosin subfragment-1 (S1) by the calponin-like protein from mussel bivalve muscle. The calponin-like protein (Cap) is a 40-kDa actin-binding protein from the bivalve muscle of the mussel Crenomytilus grayanus. Kinetic parameters V_max and K_ATPase of actomyosin ATPase in the absence and the presence of Cap were determined to investigate the mechanism of inhibition. It was found that Cap mainly causes increase in K_ATPase value and to a lesser extent the decrease in V_max, which indicates that it is most likely a competitive inhibitor of actomyosin ATPase. Analysis of V_max and K_ATPase parameters in the presence of tropomyosin revealed that the latter is a noncompetitive inhibitor of the actomyosin ATPase.     

Temperature Responses of Photosynthesis and Respiration of Maize (<Emphasis Type="Italic">Zea mays</Emphasis>) Plants to Experimental Warming

Understanding the key processes and mechanisms of photosynthetic and respiratory acclimation of maize (Zea mays L.) plants in response to experimental warming may further shed lights on the changes in the carbon exchange and Net Primary Production (NPP) of agricultural ecosystem in a warmer climate regime. In the current study, we examined the temperature responses and sensitivity of foliar photosynthesis and respiration for exploring the mechanisms of thermal acclimation associated with physiological and biochemical processes in the North China Plain (NCP) with a field manipulative warming experiment. We found that thermal acclimation of A_n as evidenced by the upward shift of A_n-T was determined by the maximum velocity of Rubisco carboxylation (V_cmax), the maximum rate of electron transport (J_max), and the stomatal- regulated CO₂ diffusion process (g_s), while the balance between respiration and photosynthesis (R_d/A_g), and/or regeneration of RuBP and the Rubisco carboxylation (J_max/V_cmax) barely affected the thermal acclimation of A_n. We also found that the temperature response and sensitivity of R_d was closely associated with the changes in foliar N concentration induced by warming. These results suggest that the leaf-level thermal acclimation of photosynthesis and respiration may mitigate or even offset the negative impacts on maize from future climate warming, which should be considered to improve the accuracy of process-based ecosystem models under future climate warming.     

In Vitro Functional Characterisation of Cytochrome P450 (CYP) 2C19 Allelic Variants <Emphasis Type="Italic">CYP2C19*23</Emphasis> and <Emphasis Type="Italic">CYP2C19*24</Emphasis>

Cytochrome P450 (CYP) 2C19 is essential for the metabolism of clinically used drugs including omeprazole, proguanil, and S-mephenytoin. This hepatic enzyme exhibits genetic polymorphism with inter-individual variability in catalytic activity. This study aimed to characterise the functional consequences of CYP2C19*23 (271 G>C, 991 A>G) and CYP2C19*24 (991 A>G, 1004 G>A) in vitro. Mutations in CYP2C19 cDNA were introduced by site-directed mutagenesis, and the CYP2C19 wild type (WT) as well as variants proteins were subsequently expressed using Escherichia coli cells. Catalytic activities of CYP2C19 WT and those of variants were determined by high performance liquid chromatography-based essay employing S-mephenytoin and omeprazole as probe substrates. Results showed that the level of S-mephenytoin 4′-hydroxylation activity of CYP2C19*23 (V _max 111.5 ± 16.0 pmol/min/mg, K _m 158.3 ± 88.0 μM) protein relative to CYP2C19 WT (V _max 101.6 + 12.4 pmol/min/mg, K _m 123.0 ± 19.2 μM) protein had no significant difference. In contrast, the K _m of CYP2C19*24 (270.1 ± 57.2 μM) increased significantly as compared to CYP2C19 WT (123.0 ± 19.2 μM) and V _max of CYP2C19*24 (23.6 ± 2.6 pmol/min/mg) protein was significantly lower than that of the WT protein (101.6 ± 12.4 pmol/min/mg). In vitro intrinsic clearance (CL_int = V _max/K _m) for CYP2C19*23 protein was 85.4 % of that of CYP2C19 WT protein. The corresponding CL_int value for CYP2C19*24 protein reduced to 11.0 % of that of WT protein. These findings suggested that catalytic activity of CYP2C19 was not affected by the corresponding amino acid substitutions in CYP2C19*23 protein; and the reverse was true for CYP2C19*24 protein. When omeprazole was employed as the substrate, K _m of CYP2C19*23 (1911 ± 244.73 μM) was at least 100 times higher than that of CYP2C19 WT (18.37 ± 1.64 μM) and V _max of CYP2C19*23 (3.87 ± 0.74 pmol/min/mg) dropped to 13.4 % of the CYP2C19 WT (28.84 ± 0.61 pmol/min/mg) level. Derived from V _max/K _m, the CL_int value of CYP2C19 WT was 785 folds of CYP2C19*23. K _m and V _max values could not be determined for CYP2C19*24 due to its low catalytic activity towards omeprazole 5′-hydroxylation. Therefore, both CYP2C19*23 and CYP2C19*24 showed marked reduced activities of metabolising omeprazole to 5-hydroxyomeprazole. Hence, carriers of CYP2C19*23 and CYP2C19*24 allele are potentially poor metabolisers of CYP2C19-mediated substrates.     

Growth and photosynthetic response of two larches exposed to O<Subscript>3</Subscript> mixing ratios ranging from preindustrial to near future

In this study, we questioned whether ground-level ozone (O₃) induces hormesis in Japanese larch (Larix kaempferi) and its hybrid F₁ (L. gmelinii var. japonica × L. kaempferi). In order to answer the question, we exposed seedlings of both taxa to four O₃ treatments [ranging from ≈10 to 60 nmol(O₃) mol^–1] in open-top chambers for two consecutive growing seasons. We found a hormetic response in maximum photosynthetic rate (P_Nmax) at 1700 μmol(CO₂) mol^–1 and maximum rates of carboxylation (V_cmax) and electron transport (J_max) in both larches. Stimulation of P_Nmax, V_cmax, and J_max did not lead to suppressed plant productivity in Japanese larch, which followed a stress-tolerant strategy, but it did lead to suppressed plant productivity in hybrid larch which followed a competitive strategy. These findings are the first to suggest that stimulation of physiological functions by low O₃ exposures may have negative consequences for larch reproduction.     

The structure of biogenic habitat and epibiotic assemblages associated with the global invasive kelp <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> in comparison to native macroalgae

Kelp forests dominate temperate and polar rocky coastlines and represent critical marine habitats because they support elevated rates of primary and secondary production and high biodiversity. A major threat to the stability of these ecosystems is the proliferation of non-native species, such as the Japanese kelp Undaria pinnatifida (‘Wakame’), which has recently colonised natural habitats in the UK. We quantified the abundance and biomass of U. pinnatifida on a natural rocky reef habitat over 10 months to make comparisons with three native canopy-forming brown algae (Laminaria ochroleuca, Saccharina latissima, and Saccorhiza polyschides). We also examined the biogenic habitat structure provided by, and epibiotic assemblages associated with, U. pinnatifida in comparison to native macroalgae. Surveys conducted within the Plymouth Sound Special Area of Conservation indicated that U. pinnatifida is now a dominant and conspicuous member of kelp-dominated communities on natural substrata. Crucially, U. pinnatifida supported a structurally dissimilar and less diverse epibiotic assemblage than the native perennial kelp species. However, U. pinnatifida-associated assemblages were similar to those associated with Saccorhiza polyschides, which has a similar life history and growth strategy. Our results suggest that a shift towards U. pinnatifida dominated reefs could result in impoverished epibiotic assemblages and lower local biodiversity, although this could be offset, to some extent, by the climate-driven proliferation of L. ochroleuca at the poleward range edge, which provides complex biogenic habitat and harbours relatively high biodiversity. Clearly, greater understanding of the long-term dynamics and competitive interactions between these habitat-forming species is needed to accurately predict future biodiversity patterns.     

Rearrangement of leaf traits with changing source-sink relationship in blueberry (Vaccinium corymbosum L.) leaves

The source-sink relationship is one of major determinants of plant performance. The influence of reproductive sink demand on light-saturated photosynthesis (P_max), dark respiration (R_D), stomatal conductance (g_s), intrinsic water-use efficiency (WUE_i), contents of soluble sugar (SSC), nitrogen, carbon, and photosynthetic pigments was examined in blueberry (Vaccinium corymbosum L. cv. ‘Brigitta’) during the final stage of rapid fruit growth. Measurements were performed three times per day on developed, sun-exposed leaves of girdled shoots with 0.1, 1, and 10 fruit per leaf (0.1F:L, 1F:L, and 10F:L, respectively) and nongirdled shoots bearing one fruit per leaf (NG). Girdling and lower fruit amount induced lower P_max, g_s, N, and total chlorophyll (Chl) and higher WUE_i, SSC, R_D, Chl a/b ratio and carotenoids-to-chlorophylls ratio (Car/Chl) for the 1F:L and 0.1F:L treatments. The impact of girdling was counterbalanced by 10F:L, with NG and 10F:L having similar values. Variables other than P_max, R_D, g_s, WUE_i, and SSC were unaffected throughout the course of the day. P_max and g_s decreased during the course of the day, but g_s decreased more than P_max in the afternoon, while WUE_i was increasing in almost all treatments. SSC increased from the morning until afternoon, whereas R_D peaked at noon regardless of the treatment. Generally, P_max was closely and negatively correlated to SSC, indicating that sugar-sensing mechanisms played an important role in regulation of blueberry leaf photosynthesis. With respect to treatments, P_max and N content were positively related, while R_D was not associated to substrate availability. The enhanced Car/Chl ratio showed a higher photoprotection under the lower sink demand. Changes in the source-sink relationship in ‘Brigitta’ blueberry led to a rearrangement of physiological and structural leaf traits which allowed adjusting the daily balance between carbon assimilation and absorbed light energy.     

Assessing biodegradation of furfuryl alcohol using <Emphasis Type="Italic">Pseudomonas putida</Emphasis> MTCC 1194 and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> MTCC 1034 and its kinetics

The biodegradation of furfuryl alcohol (FA) in shake flask experiments using a pure culture of Pseudomonas putida (MTCC 1194) and Pseudomonas aeruginosa (MTCC 1034) was studied at 30 °C and pH 7.0. Experiments were performed at different FA concentrations ranging from 50 to 500 mg/l. Before carrying out the biodegradation studies, the bacterial strains were acclimatized to the concentration of 500 mg/l of FA by gradually raising 100 mg/l of FA in each step. The well acclimatized culture of P. putida and P. aeruginosa degraded about 80 and 66% of 50 mg/l FA, respectively. At higher concentration of FA, the percentage of FA degradation decreased. The purpose of this study was to determine the kinetics of biodegradation of FA by measuring biomass growth rates and concentration of FA as a function of time. Substrate inhibition was calculated from experimental growth parameters using the Haldane equation. Data for P. putida were determined as µ _max ?=?0.23 h^?1, K _s ?=?23.93 mg/l and K _i ?=?217.1 mg/l and for P. aeruginosa were determined as µ _max ?=?0.13 h^?1, K _s ?=?21.3 mg/l and K _i ?=?284.9 mg/l. The experimental data were fitted in Haldane, Aiba and Edwards inhibition models.     

Mesophyll conductance to CO<Subscript>2</Subscript> in leaves of Siebold’s beech (<Emphasis Type="Italic">Fagus crenata</Emphasis>) seedlings under elevated ozone

Ozone is an air pollutant that negatively affects photosynthesis in woody plants. Previous studies suggested that ozone-induced reduction in photosynthetic rates is mainly attributable to a decrease of maximum carboxylation rate (V_cmax) and/or maximum electron transport rate (J_max) estimated from response of net photosynthetic rate (A) to intercellular CO₂ concentration (C_i) (A/C_i curve) assuming that mesophyll conductance for CO₂ diffusion (g_m) is infinite. Although it is known that C_i-based V_cmax and J_max are potentially influenced by g_m, its contribution to ozone responses in C_i-based V_cmax and J_max is still unclear. In the present study, therefore, we analysed photosynthetic processes including g_m in leaves of Siebold’s beech (Fagus crenata) seedlings grown under three levels of ozone (charcoal-filtered air or ozone at 1.0- or 1.5-times ambient concentration) for two growing seasons in 2016–2017. Leaf gas exchange and chlorophyll fluorescence were simultaneously measured in July and September of the second growing season. We determined the A, stomatal conductance to water vapor and g_m, and analysed A/C_i curve and A/C_c curve (C_c: chloroplast CO₂ concentration). We also determined the Rubisco and chlorophyll contents in leaves. In September, ozone significantly decreased C_i-based V_cmax. At the same time, ozone decreased g_m, whereas there was no significant effect of ozone on C_c-based V_cmax or the contents of Rubisco and chlorophyll in leaves. These results suggest that ozone-induced reduction in C_i-based V_cmax is a result of the decrease in g_m rather than in carboxylation capacity. The decrease in g_m by elevated ozone was offset by an increase in C_i, and C_c did not differ depending on ozone treatment. Since C_c-based V_cmax was also similar, A was not changed by elevated ozone. We conclude that g_m is an important factor for reduction in C_i-based V_cmax of Siebold’s beech under elevated ozone.     

A new invasive species of buprestid beetles in the Russian fauna: <Emphasis Type="Italic">Lamprodila</Emphasis> (<Emphasis Type="Italic">Palmar</Emphasis>) <Emphasis Type="Italic">festiva</Emphasis> (L.) (Coleoptera,Buprestidae), a pest of Cupressaceae

The buprestid beetle Lamprodila (Palmar) festiva (L.) (Coleoptera, Buprestidae, Poecilonoini), an invasive pest of cultivated Cupressaceae such as Thuja, Chamaecyparis, Cupressus, and Juniperus in the Greater Sochi area (the Russian Black Sea coast), is recorded for the first time for Russia and the former USSR. Data on the systematic position, diagnostic characters, distribution, host plants, biology of the new pest, and its damage to urban plantations are discussed. Recent records of this species in the new areas of Central and Eastern Europe as well as on the Black Sea coast of the Caucasus suggest expansion of its range during the recent decades.     

<Emphasis Type="Italic">Macrocystis integrifolia</Emphasis> and <Emphasis Type="Italic">Lessonia trabeculata</Emphasis> (Laminariales; Phaeophyceae) kelp habitat structures and associated macrobenthic community off northern Chile

Macrocystis integrifolia and Lessonia trabeculata form vast kelp beds providing a three-dimensional habitat for a diverse invertebrate and fish fauna off northern Chile. Habitat modifications caused by the El Niño Southern Oscillation (ENSO) are likely to alter the inhabiting communities. The aim of this study was to reveal relationships between distinct habitat structures of a M. integrifolia kelp bed, a dense L. trabeculata kelp bed and L. trabeculata patches colonizing a barren ground, and the associated dominant macrobenthic key species. Seasonally 15 sampling units (10 m² each) of any of the three habitats were monitored by SCUBA divers, which counted sporophytes and macroinvertebrates living between the latter. Furthermore, samples of plants were analysed in the laboratory to measure the morphological variables: total plant length, maximal holdfast diameter, stipe number, number of dichotomies per stipe, frond width and total drained wet mass. Multivariate analysis showed that the L. trabeculata kelp bed is denser, with a higher number of dichotomies per stipe, whereas sporophytes of M. integrifolia are longer with more stipes and wider fronds. Sporophytes of L. trabeculata patchily present on barren ground are shorter and have more stipes compared with those in the dense L. trabeculata kelp bed. Thus, the habitats provide different three-dimensional structures. The associated macrobenthic communities show a variable degree of overlapping; however, key faunal assemblages were distinguished for each habitat. Our study provides evidence that habitat diversity drives species diversity, the more homogeneous, monospecifically composed kelp bed habitats show comparatively low diversity, mainly caused by the dominance of the ascidian P. chilensis and T. tridentata in the M. integrifolia bed, and the mussel A. ater only present in the L. trabeculata bed. Species richness and diversity is highest in the heterogeneous habitat where L. trabeculata patches interrupt the barren ground. Our study revealed morphological differences between M. integrifolia and L. trabeculata kelp beds reflected in stipe number, plant length, dichotomies per stipe, and wet mass, which influence the composition of the associated characteristic fauna and its functional relations i.e. T. niger and T. tridentata.     

Characterization of mating-type idiomorphs suggests that <Emphasis Type="Italic">Morchella importuna,Mel-20</Emphasis> and <Emphasis Type="Italic">M. sextelata</Emphasis> are heterothallic

Morels (Morchella spp.) are highly prized for their culinary qualities and intensively collected worldwide by mycophiles. Morels are divided into three clades by phylogenetic analyses: black morels, yellow morels and the rufobrunnea clade. Morchella importuna, Mel-20 and M. sextelata are included in the black morel clade and are widely distributed in Yunnan province, China. M. importuna and M. sextelata have been artificially cultured in recent years, but their life cycles and reproductive systems are still poorly understood, which delays the progress of morel cultivation. In this study, the genomes of two ascospore isolates of M. importuna with opposite mating-type were sequenced and two idiomorphs, MAT1–1 and MAT1–2, were identified. The MAT1–2 idiomorph was 6.7 kb in length containing a single MAT1–2-1 gene, and the MAT1–1 idiomorph was 10.5 kb containing a MAT1–1-1 gene and two other open reading frames (ORFs), GME3123 and GME3124. These ORFs differed greatly from the homologues of previously published mating-type genes; therefore, we speculate that they are novel mating genes found only in morels. Single-ascospore populations of M. importuna, M. sextelata and Mel-20 were analysed, and the result indicated that the ratios of MAT1–1- and MAT1–2-harbouring idiomorphs were not significantly different from a 1:1 ratio. The results suggest that these three black morels are heterothallic.     

Cloning and expression of <Emphasis Type="Italic">β</Emphasis>-glucosidase gene from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> into <Emphasis Type="Italic">E. coli</Emphasis> BL 21 (DE3)

A 1.4 Kb fragment of Bacillus licheniformis ATCC 14580 encoding β-glucosidase was cloned and expressed in Escherichia coli. β-Glucosidase expressed by E. coli harboring cloned gene was located entirely in the intracellular fraction. Recombinant β-glucosidase protein was purified to homogeneity level and the molecular weight was found to be 53 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. It gave maximum activity at 50°C and pH 6. K _m and V _max were 0.206 mM and 1.26 U/mg, respectively, with p-nitrophenyl-β-D-glucopyranoside, while activation energy E_a, enthalpy of activation ?H and entropy of activation ΔS were found to be 66.31 kJ/mol, 64.04 kJ/mol and 48.28 J/mol/K, respectively. The pK_a1 and pK_a2 of the ionizable groups of active site residues involved in V_max were found to be 5.5 and 7.0, respectively. When the recombinant β-glucosidase protein was used as a member of consortium with endoglucanase and exoglucanase for the saccharification of wheat straw, 123% increase in saccharification was observed.     

Expression and characterization of glutamate decarboxylase from <Emphasis Type="Italic">Lactobacillus brevis</Emphasis> HYE1 isolated from <Emphasis Type="Italic">kimchi</Emphasis>

A putative gene (gadlbhye1) encoding glutamate decarboxylase (GAD) was cloned from Lactobacillus brevis HYE1 isolated from kimchi, a traditional Korean fermented vegetable. The amino acid sequences of GADLbHYE1 showed 48% homology with the GadA family and 99% identity with the GadB family from L. brevis. The cloned GADLbHYE1 was functionally expressed in Escherichia coli using inducible expression vectors. The expressed recombinant GADLbHYE1 was successfully purified by Ni–NTA affinity chromatography, and had a molecular mass of 54 kDa with optimal hydrolysis activity at 55 °C and pH 4.0. Its thermal stability was determined to be higher than that of other GADs from L. brevis, based on its melting temperature (75.18 °C). Kinetic parameters including K_m and V_max values for GADLbHYE1 were 4.99 mmol/L and 0.224 mmol/L/min, respectively. In addition, the production of gamma-aminobutyric acid in E. coli BL21 harboring gadlbhye1/pET28a was increased by adding pyridoxine as a cheaper coenzyme.     

Assessment of Maturity,Reproduction and Reproductive Potentials of Torpedo Scad, <Emphasis Type="Italic">Megalaspis cordyla</Emphasis> (Linnaeus, 1758) from Northern Arabian Sea Coast of Pakistan

Port landing specimens of torpedo scad, Megalaspis cordyla were collected at monthly intervals from August 2013 to June 2014 from the northern Arabian Sea coast of Pakistan. The life history characteristics revealed that torpedo scad has a prolonged breeding season which occurred with two peaks: from May to June and from November to February. The spawning seasonality was also validated with microscopic gonad examination.The highest GSI value was noted in May and January whereas the lowest in November was recorded for both sexes. The age at which individuals of both sexes become 50% mature (t₅₀) was estimated as 2.44 year. Life span (t_max) calculated as 3.96 years for male and females. The size of 270 and 265 mm at which 50% individuals attained sexual maturity (L₅₀) was determined for males and females respectively. The reproductive potential (fecundity)was made from ten ripe females ranged from 29–43.8 cm TL and weighing 220–540 g of IV–V developmental stage was enumerated as 32306–236677 eggs (CV = 2.135) with an average number of eggs 86544 counted per ripe female/season. This study contains fundamental data of an important fish species in the northern Arabian Sea coast of Pakistan. It provides vital information to the fisheries managers for implementation on sustainable use of the resource during spawning season.