The NAD-linked soluble hydrogenase from Alcaligenes eutrophus H16: detection and characterization of EPR signals deriving from nickel and flavin

 In this study we confirmed the previous observation that the cytoplasmic NAD-linked hydrogenase of Alcaligenes eutrophus H16 is EPR-silent in the oxidized state. We also demonstrated the presence of significant Ni-EPR signals when the enzyme was either reduced with the natural electron carrier NADH (5–10 mM) or carefully titrated with sodium dithionite to an intermediate, narrow redox potential range (–280 to –350 mV). Reduction with NADH under argon atmosphere led to a complex EPR spectrum at 80 K with g values at 2.28, 2.20, 2.14, 2.10, 2.05, 2.01 and 2.00. This spectrum could be differentiated by special light/dark treatments into three distinct signals: (1) the "classical" Ni-C signal with g values at 2.20, 2.14 and 2.01, observed with many hydrogenases in the reduced, active state; (2) the light-induced signal (Ni-L) with g values at 2.28, 2.10 and 2.05 and (3) a flavin radical (FMN semiquinone) signal at g = 2.00. The assignment of the Ni-EPR signal was clearly confirmed by EPR spectra of hydrogenase labeled with ⁶¹Ni (nuclear spin I = 3/2) yielding a broadening of the Ni spectra at all g values and a resolved ⁶¹Ni hyperfine splitting into four lines of the low field edge in the case of the light-induced Ni-EPR signal. The redox potentials determined at pH 7.0 for the described redox components were: for FMN –170 mV (midpoint potential, E_m, for appearance), –200 mV (EPR signal intensity maximum) and –230 mV (E_m for disappearance); for the Ni centre (Ni-C), –290 mV (E_m for appearance), –305 mV (signal intensity maximum) and –325 mV (E_m for disappearance). Exposure of the NADH-reduced hydrogenase to carbon monoxide led to an apparent Ni-CO species indicated by a novel rhombic EPR signal with g values at 2.35, 2.08 and 2.01. Received: 19 July 1995 / Accepted: 10 September 1995     

Length to weight ratio of four fish species in estuary areas in the Northeast region of Brazil

The length to weight ratio (LWR) was used to estimate populations of four fish species sampled on the Amazon coast of the state of Maranhão, Brazil. The fishes were sampled in 2018 and 2019 by artisanal coastal fishing, using gillnets (0.20–0.60 mm). The parameters a and b of the equation W_T = a L_T^b were estimated. The obtained LWRs were W_T = 0.06LT^2.93, (r²) = .989 for Oligoplites saliens; W_T = 0.061L_T^2.57, (r²) = .982 for Peprilus crenulatus; W_T = 0.014L_T^2.80, (r²) = .985 for Bagre bagre; and W_T = 0.035L_T^3.21, (r²) = .981 for Nebris microps.     

Inhibition of the [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F by carbon monoxide: An FTIR and EPR spectroscopic study

X-ray crystallographic studies [Ogata et al., J. Am. Chem. Soc. 124 (2002) 11628-11635] have shown that carbon monoxide binds to the nickel ion at the active site of the [NiFe] hydrogenase from Desulfovibriovulgaris Miyazaki F and inhibits its catalytic function. In the present work spectroscopic aspects of the CO inhibition for this bacterial organism are reported for the first time and enable a direct comparison with the existing crystallographic data. The binding affinity of each specific redox state for CO is probed by FTIR spectro-electrochemistry. It is shown that only the physiological state Ni-SI_a reacts with CO. The CO-inhibited product state is EPR-silent (Ni²⁺) and exists in two forms, Ni-SCO and Ni-SCO_red. At very negative potentials, the exogenous CO is electrochemically detached from the active site and the active Ni-R states are obtained. At temperatures below 100 K, photodissociation of the extrinsic CO from the Ni-SCO state results in Ni-SI_a that is identified to be the only light-induced state. In the dark, rebinding of CO takes place; the recombination rate constants are of biexponential character and the activation barrier is determined to be approximately 9 kJ mol⁻¹. In addition, formation of a paramagnetic CO-inhibited state (Ni-CO) was observed that results from the interaction of carbon monoxide with the Ni-L state. It is proposed that the nickel in Ni-CO is in a formal monovalent state (Ni¹⁺).     

Comparative Tolerances of Various <Emphasis Type="Italic">Beauveria bassiana</Emphasis> Isolates to UV-B Irradiation with a Description of a Modeling Method to Assess Lethal Dose

The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1–1.6 J cm⁻² (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0–2.61 mW cm⁻². Irradiated conidia were then incubated for 24 h at 25°C under saturated humidity. The ratio of germination at each dose over that in the blank control was defined as survival index (I _s). For all isolates, the I _s − D observations fit well with the survival model I _s = 1/[1 + exp(a + bD)] (0.94 ≤ r ² ≤ 0.99) generated widely spanned lethal doses of 0.154–0.928, 0.240–1.139, and 0.383–1.493 J cm⁻² for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm⁻² measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses.     

MR Proton Relaxivities of Some Ions, Albumin, and Cholesterol Added to Odontogenic Jaw Cysts

The relaxation rates (1 / T ₁ and 1 / T ₂) in cysts have already been analyzed in terms of materials such as albumin, cholesterol, manganese, iron, and copper. However, the relaxivities of these materials have not been determined yet. In this work, five sets containing the ions, albumin, and cholesterol were prepared by addition of increasing concentration of one material to each set. The relaxation times in these sets were measured by MRI, and the relaxation rates were fitted versus concentrations. The slopes of the fits were used as relaxivities. The (r ₁, r ₂) values of manganese, iron, and copper in mM⁻¹ s⁻¹, and those of albumin and cholesterol in (g/dl)⁻¹ s⁻¹ were found to be (32.64, 89.77), (0.31, 1.19), (0.5, 1.479), (0.01, 0.066) and (0.03, 0.458), respectively. The r ₂/r ₁ ratio ranged from 2.75 to 15.27. Manganese is an efficient relaxer, but iron and copper are poor ones. Albumin and cholesterol are efficient relaxers for only T ₂. The contribution of water associated with native manganese of the cystic fluid to T ₁ was 0.268 s⁻¹, whereas those of water associated with native manganese, albumin, cholesterol, and iron to T ₂ were 0.736, 0.185, 0.092, and 0.076 s⁻¹, respectively. The other contributions were much smaller than 0.076 s⁻¹. Manganese is most likely the compound altering T ₁-weighted images between different jaw cysts, whereas manganese and albumin are most likely the compounds altering the T ₂-weighted images. Present data suggest that such alterations may be used to separate jaw cysts from other jaw masses. The high r ₂/r ₁ suggests that T ₂ is a more convenient parameter than T ₁ for diagnostic use. This work is a part of the PhD thesis of U. Nezih Yilmaz supervised by R. Guner.     

The cranial arterio-venous temperature difference is related to respiratory evaporative heat loss in a panting species,the sheep (<Emphasis Type="Italic">Ovis aries</Emphasis>)

Panting is a mechanism that increases respiratory evaporative heat loss (REHL) under heat load. Because REHL uses body water, it is physiologically and ecologically relevant to know under what conditions free-ranging animals use panting. We investigated whether the cranial arterio-venous temperature difference could provide information about REHL. We exposed sheep to environments varying in ambient dry bulb temperatures (Env 1: ~15°C, Env 2: ~25°C, Env 3: ~40°C, Env 4: ~40°C + infrared radiation) and measured REHL simultaneously with carotid arterial (T _car) and jugular venous (T _jug) blood temperatures, as well as brain (T _brain) and rectal (T _rec) temperatures. REHL increased significantly with ambient temperature, from 18.4 ± 4.5 W at Env 1 to 79.5 ± 12.6 W at Env 4 (P < 10⁻⁶). While there was no effect of environment on T _car (P = 0.7) or T _jug (P = 0.09), the difference between them (T _a-v = T _car − T _jug) increased from Env 1 to Env 2 (P = 0.04) and from Env 3 to Env 4 (P = 0.008). T _a-v reached a maximum of 0.7 ± 0.2°C at Env 4 and was positively correlated with REHL across environments (r ² = 0.78, F = 34.7, P < 10⁻³). Calculated cranial blood flow changed only from Env 2 to Env 3 (P = 0.002). The increase in REHL maintained homeothermy when dry heat loss decreased. While REHL could increase without generating an increase in T _a-v, any increase in T _a-v was always associated with an increase in REHL. We conclude that the cranial T _a-v provides useful information about REHL in panting animals.     

Electron spin-lattice relaxation studies of different forms of the S2 state multiline EPR signal of the Photosystem II oxygen-evolving complex

The pulsed EPR inversion recovery sequence has been utilized to monitor the temperature dependence of the electron spin-lattice relaxation rate of the Mn cluster of the Photosystem II oxygen evolving complex poised in a variety of S ₂ state forms giving rise to g = 2 multiline EPR signals. A previous study (Lorigan and Britt (1994) Biochemistry 33: 12072–12076) showed that for PS II membranes treated with 5% ethanol, the S ₂ state Mn cluster relaxes via the Orbach spin-lattice relaxation mechanism, where the relaxation is enhanced via phonon scattering off an excited state spin manifold, in this case at an energy of Δ = 36.5 cm⁻¹ above the S = 1/2 ground state giving rise to the multiline EPR signal. Parallel experiments are reported for PS II membranes with 5% methanol, treated with ammonia, and following short and long term dark adaptation. In each case, the temperature dependence of the electron spin-lattice relaxation rate is consistent with Orbach relaxation, and the range of excited state energies is relatively narrow (33.8 cm⁻¹ ≤ Δ ≤ 39.7 cm⁻¹). In addition, short term dark adapted (6 min, ‘active state’) PS II membranes show biphasic recovery traces which indicate that a minority fraction of the oxygen evolving complexes are trapped in a form with greatly slowed spin-lattice relaxation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hemoglobin senses body temperature

When aspirating human red blood cells (RBCs) into 1.3 μm pipettes (ΔP = −2.3 kPa), a transition from blocking the pipette below a critical temperature T _c = 36.3 ± 0.3°C to passing it above the T _c occurred (micropipette passage transition). With a 1.1 μm pipette no passage was seen which enabled RBC volume measurements also above T _c. With increasing temperature RBCs lost volume significantly faster below than above a T _c = 36.4 ± 0.7 (volume transition). Colloid osmotic pressure (COP) measurements of RBCs in autologous plasma (25°C ≤ T ≤ 39.5°C) showed a T _c at 37.1 ± 0.2°C above which the COP rapidly decreased (COP transition). In NMR T₁-relaxation time measurements, the T₁ of RBCs in autologous plasma changed from a linear (r = 0.99) increment below T _c = 37 ± 1°C at a rate of 0.023 s/K into zero slope above T _c (RBC T₁ transition). In conclusion: An amorphous hemoglobin–water gel formed in the spherical trail, the residual partial sphere of the aspirated RBC. At T _c, a sudden fluidization of the gel occurs. All changes mentioned above happen at a distinct T _c close to body temperature. The T _c is moved +0.8°C to higher temperatures when a D₂O buffer is used. We suggest a mechanism similar to a “glass transition” or a “colloidal phase transition”. At T _c, the stabilizing Hb bound water molecules reach a threshold number enabling a partial Hb unfolding. Thus, Hb senses body temperature which must be inscribed in the primary structure of hemoglobin and possibly other proteins. This article is dedicated to Ludwig Artmann who died on July 21, 2001 on a beautiful summer day during which we performed experiments far away. Ludwig Artmann was a man who encouraged us to be strong and to study hard no matter what were the costs.     

Stable carbon isotope characteristics of desert plants in the Junggar Basin, China

Desert plants have unique strategies for survival and growth to cope with the limited water availability in arid regions. The stable carbon isotope (δ ¹³C) provides an integrated measurement of internal plant physiological and external environmental properties affecting photosynthetic gas exchange and water use efficiency. The δ ¹³C values of 84 species in the Junggar Basin were categorized into two groups (ranged from −30.1 to −23.3‰ for C₃ and −14.9 to −9.9‰ for C₄ species, respectively). No life form differences in δ ¹³C values were detected in C₃ (p = 0.78) and C₄ plants (p = 0.63). Small differences among life forms were observed in δ ¹³C values in C₄ species with shrubs slightly depleted (−13.3‰) relative to perennials (−13.1‰) and annuals (−12.5‰). These differences suggested that δ ¹³C value could not represent a plant functional group classification based on life forms in C₄ plants in extremely arid regions. Ephemerals are all using C₃ photosynthetic pathway and no significant differences (p = 0.92) in δ ¹³C values were observed between annuals (−26.5‰) and perennials (−26.4‰). The δ ¹³C values of Tulipa iliensis (an important ephemeral species distributed widely in the Junggar Basin) among nine natural populations were positively correlated with leaf (r ² = 0.46, p = 0.046) and soil (r ² = 0.67, p = 0.007) total nitrogen content, and negatively correlated with leaf (r ² = 0.48, p = 0.039) and soil (r ² = 0.79, p = 0.001) water content. This indicated that the variation in δ ¹³C values of T. iliensis was probably caused by both water availability associated stomatal openness and nitrogen availability associated photosynthetic capacity. T. iliensis is very sensitive to water and nitrogen availability in soil.     

Comparison of phenotypic and molecular distances to predict heterosis and F1 performance in Ethiopian mustard (Brassica carinata A. Braun)

Predicting heterosis and F₁ performance from the parental generation could largely enhance the efficiency of breeding hybrid or synthetic cultivars. This study was undertaken to determine the relationship between parental distances estimated from phenotypic traits or molecular markers with heterosis, F₁ performance and general combining ability (GCA) in Ethiopian mustard (Brassica carinata). Nine inbred lines representing seven different geographic regions of Ethiopia were crossed in half-diallel. The nine parents along with their 36 F₁s were evaluated in a replicated field trail at three locations in Ethiopia. Distances among the parents were calculated from 14 phenotypic traits (Euclidean distance, ED) and 182 random amplified polymorphic DNA (RAPD) markers (Jaccard’s distances, JD), and correlated with heterosis, F₁ performance and GCA sum of parents (GCA_sum). The correlation between phenotypic and molecular distances was low (r=0.34, P≤0.05). Parents with low molecular distance also had low phenotypic distance, but parents with high molecular distance had either high, intermediate or low phenotypic distance. Phenotypic distance was highly significantly correlated with mid-parent heterosis (r=0.53), F₁ performance (r=0.61) and GCA (r=0.79) for seed yield. Phenotypic distance was also positively correlated with (1) heterosis, F₁ performance and GCA for plant height and seeds plant⁻¹, (2) heterosis for number of pods plant⁻¹, and (3) F₁ performance for 1,000 seed weight. Molecular distance was correlated with GCA_sum (r=0.36, P≤0.05) but not significantly with heterosis and F₁ performance for seed yield. For each parent a mean distance was calculated by averaging the distances to the eight other parents. Likewise, mean heterosis was estimated by averaging the heterosis obtained when each parent is crossed with the other eight. For seed yield, both mean ED and JD were significantly correlated with GCA (r=0.90, P≤0.01 for ED and r=0.68, P≤0.05 for JD) and mean heterosis (r=0.79, P≤0.05 for ED and r=0.77, P≤0.05 for JD). In conclusion, parental distances estimated from phenotypic traits better predicted heterosis, F₁ performance and GCA than distances estimated from RAPD markers. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

<Emphasis Type="Italic">Marinobacter zhanjiangensis</Emphasis> sp. nov., a marine bacterium isolated from sea water of a tidal flat of the South China Sea

A novel Gram-negative, catalase- and oxidase-positive, non-sporulating, rod-shaped, aerobic bacterium, designated strain JSM 078120^T, was isolated from sea water collected from a tidal flat of Naozhou Island, South China Sea. Growth occurred with 1–15% (w/v) total salts (optimum, 2–4%), at pH 6.0–10.0 (optimum, pH 7.5) and at 4–35°C (optimum, 25–30°C). The major cellular fatty acids were C_18:1 ω9c, C_16:0, C_12:0 3-OH and C_16:1 ω7c. The predominant respiratory quinone was ubiquinone Q-9, and the genomic DNA G + C content was 60.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 078120^T should be assigned to the genus Marinobacter, being related most closely to the type strains of Marinobacter segnicrescens (sequence similarity 98.2%), Marinobacter bryozoorum (97.9%) and Marinobacter gudaonensis (97.6%). The sequence similarities between the novel isolate and the type strains of other recognized Marinobacter species ranged from 96.7 (with Marinobacter salsuginis) to 93.3% (with Marinobacter litoralis). The levels of DNA–DNA relatedness between strain JSM 078120^T and the type strains of M. segnicrescens, M. bryozoorum and M. gudaonensis were 25.3, 20.6 and 18.8%, respectively. The combination of phylogenetic analysis, DNA–DNA relatedness, phenotypic characteristics and chemotaxonomic data supported the view that strain JSM 078120^T represents a novel species of the genus Marinobacter, for which the name Marinobacter zhanjiangensis sp. nov. is proposed. The type strain is JSM 078120^T (= CCTCC AB 208029^T = DSM 21077^T = KCTC 22280^T). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain JSM 078120^T is FJ425903.     

Winter body temperature patterns in free-ranging Cape ground squirrel, Xerus inauris: no evidence for torpor

The body temperature (T _b) of Cape ground squirrels (Xerus inauris, Sciuridae) living in their natural environment during winter has not yet been investigated. In this study we measured abdominal T _b of eight free-ranging Cape ground squirrels over 27 consecutive days during the austral winter. Mean daily T _b was relatively stable at 37.0 ± 0.2°C (range 33.4 to 40.2°C) despite a marked variation in globe temperature (T _g) (range −7 to 37°C). Lactating females (n = 2) consistently had a significantly higher mean T _b (0.7°C) than non-lactating females (n = 3) and males. There was a pronounced nychthemeral rhythm with a mean active phase T _b of 38.1 ± 0.1°C and a mean inactive phase T _b of 36.3 ± 0.3°C for non-lactating individuals. Mean daily amplitude of T _b rhythm was 3.8 ± 0.2°C. T _b during the active phase closely followed T _g and mean active phase T _b was significantly correlated with mean active phase T _g (r ² = 0.3–0.9; P < 0.01). There was no evidence for daily torpor or pronounced hypothermia during the inactive phase, and mean minimum inactive phase T _b was 35.7 ± 0.3°C for non-lactating individuals. Several alternatives (including nocturnal huddling, an aseasonal breeding pattern and abundant winter food resources) as to why Cape ground squirrels do not employ nocturnal hypothermia are discussed.     

Characterization of a HoxEFUYH type of [NiFe] hydrogenase from <Emphasis Type="Italic">Allochromatium vinosum</Emphasis> and some EPR and IR properties of the hydrogenase module

A soluble hydrogenase from Allochromatium vinosum was purified. It consisted of a large (M _r = 52 kDa) and a small (M _r = 23 kDa) subunit. The genes encoding for both subunits were identified. They belong to an open reading frame where they are preceded by three more genes. A DNA fragment containing all five genes was cloned and sequenced. The deduced amino acid sequences of the products characterized the complex as a member of the HoxEFUYH type of [NiFe] hydrogenases. Detailed sequence analyses revealed binding sites for eight Fe–S clusters, three [2Fe–2S] clusters and five [4Fe–4S] clusters, six of which are also present in homologous subunits of [FeFe] hydrogenases and NADH:ubiquione oxidoreductases (complex I). This makes the HoxEFUYH type of hydrogenases the one that is evolutionary closest to complex I. The relative positions of six of the potential Fe–S clusters are predicted on the basis of the X-ray structures of the Clostridium pasteurianum [FeFe] hydrogenase I and the hydrophilic domain of complex I from Thermus thermophilus. Although the HoxF subunit contains binding sites for flavin mononucleotide and NAD(H), cell-free extracts of A. vinosum did not catalyse a H₂-dependent reduction of NAD⁺. Only the hydrogenase module (HoxYH) could be purified. Its electron paramagnetic resonance (EPR) and IR spectral properties showed the presence of a Ni–Fe active site and a [4Fe–4S] cluster. Its activity was sensitive to carbon monoxide. No EPR signals from a light-sensitive Ni_a–C* state could be observed. This study presents the first IR spectroscopic data on the HoxYH module of a HoxEFUYH type of [NiFe] hydrogenase.     

Effects of the invasive plant Mikania micrantha H.B.K. on soil nitrogen availability through allelopathy in South China

Allelopathy has been regarded as a mechanism for successful exotic plant invasion. However, it is not clear if and what effects of allelopathic substances may exert on soil nutrient. The exotic plant Mikania micrantha H.B.K. (M. micrantha) has invaded many forests in south China, and recent studies have suggested it has allelopathic potential for other plants and soil microbial community. Thus, we hypothesized that M. micrantha could influence soil nutrients and N transformation through allelopathy. We measured total C and N, NO₃ ⁻, NH₄ ⁺ and pH of the soil beneath M. micrantha and the adjacent open soil, and then measured the above soil properties after treating soil with 3 concentrations of aqueous extracts of M. micrantha (T₁: 0.005 g ml⁻¹; T₂: 0.025 g ml⁻¹; T₃: 0.100 g ml⁻¹). In addition, a bioassay was conducted to determine the allelopathic potential of the soil beneath M. micrantha. The results showed that M. micrantha significantly affected soil nutrients and N transformation. Soil beneath M. micrantha had inhibitory effects on seed germination and seedling growth of test plant, and had significantly higher C, N, ammonia, net nitrification rate than those of open soil. The plant extracts decreased soil pH, and T₁ decreased it the most, and it increased soil C and N, and T₁ represented the greatest increase in both C and N. The extracts also increased both NO₃ ⁻ and NH₄ ⁺ in soil, whereas no significant difference existed among the 3 extract treatments. Compared to the water control, the soil net mineralization rate was higher under T₁, while lower under T₂ and T₃. However, the extracts increased the soil nitrification rates under all the treatments (T₁, T₂ and T₃). Our results suggest that the water soluble allelochemicals of M. micrantha improve soil nutrient availability, through which the invasive plant M. micrantha may successfully invade and establish in new habitats.     

Understanding the Influence of State/Phase Transitions on Ice Recrystallization in Atlantic Salmon (Salmo salar) During Frozen Storage

Temperature fluctuations during storage and distribution of frozen foods lead to ice recrystallization and microstructural modifications that can affect food quality. Low temperature transitions may occur in frozen foods due to temperature fluctuations, resulting in less viscous and partially melted food matrices. This study systematically investigated the influence of state/phase transitions and temperature fluctuations on ice recrystallization during the frozen storage of salmon fillets. Using a modulated differential scanning calorimeter, we identified the characteristics glass transition temperature (T _g ′) of −27 °C and the onset temperature for ice crystal melting (T _m ′) of −17 °C in salmon. The temperature of salmon fillets in sealed plastic trays was lowered to −35 °C in a freezer to achieve the glassy state. The temperature (T) of frozen salmon fillets in sealed plastic trays was modulated to achieve a rubbery state (T > T _m ′), a partially freeze-concentrated state (T _g ′ < T < T _m ′) and a glassy state (T < T _g ′). We performed temperature modulation experiments by exposing packaged salmon to room temperature twice a day for 2 to 26 min during 4 weeks of storage. We also analyzed ice crystal morphology using environmental scanning electron microscopy and X-ray computed tomography techniques to observe the pore distribution after sublimation of ice crystals. Melt–refreeze and isomass rounding mechanisms of ice recrystallization were noticed in the frozen salmon subjected to temperature modulations. Results show that ice crystal growth occurred even in the glassy state of frozen salmon during storage, with or without temperature fluctuations. Ice crystal size in frozen salmon was greater in the rubbery state (T > T _m ′) due to the increased mobility of unfrozen water compared to the glassy state. The morphological/geometric parameters of ice crystals in frozen salmon stored for 1 month differed significantly from those in 0-day storage. These findings are important to the frozen food industry because they can help optimize storage and distribution conditions and minimize quality loss of frozen salmon due to recrystallization.     

Orientation-selected ENDOR of the active center in Chromatium vinosum [NiFe] hydrogenase in the oxidized "ready" state

 Electron nuclear double resonance (ENDOR) was applied to study the active site of the oxidized "ready" state, Ni_r, in the [NiFe] hydrogenase of Chromatium vinosum. The magnetic field dependence of the EPR was used to select specific subsets of molecules contributing to the ENDOR response by stepping through the EPR envelope. Three hyperfine couplings could be clearly followed over the complete field range. Two protons, H1 and H2, display a very similar large isotropic coupling of 12.5 and 12.6 MHz, respectively. Their dipolar coupling is small (2.1 and 1.4 MHz, respectively). A third proton, H3, exhibits a small isotropic coupling of 0.5 MHz and a larger anisotropic contribution of 3.5 MHz. Based on a comparison with structural data obtained from X-ray crystallography of single crystals of hydrogenases from Desulfovibrio gigas and D. vulgaris and the known g-tensor orientation of Ni_r, an assignment of the ¹H hyperfine couplings could be achieved. H1 and H2 were assigned to the β-CH₂ protons of the bridging cysteine Cys533 and H3 could belong to a β-CH₂ proton of Cys68 or to a protonated cysteine (-SH) of Cys68 or Cys530. Received: 26 November 1998 / Accepted: 1 April 1999     

<Emphasis Type="Italic">Luteimonas aestuarii</Emphasis> sp. nov., isolated from tidal flat sediment

A novel bacterium B9^T was isolated from tidal flat sediment. Its morphology, physiology, biochemical features, and 16S rRNA gene sequence were characterized. Colonies of this strain are yellow and the cells are Gram-negative, rod-shaped, and do not require NaCl for growth. The 16S rRNA gene sequence similarity indicated that strain B9^T is associated with the genus Lysobacter (≤ 97.2%), Xanthomonas (≤ 96.8%), Pseudomonas (≤ 96.7%), and Luteimonas (≤ 96.0%). However, within the phylogenetic tree, this novel strain shares a branching point with the species Luteimonas composti CC-YY255^T (96.0%). The DNA-DNA hybridization experiments showed a DNA-DNA homology of 23.0% between strain B9^T and Luteimonas mephitis B1953/27.1^T. The G+C content of genomic DNA of the type strain is 64.7 mol% (SD, 1.1). The predominant fatty acids are iso-C_11:0, iso-C_15:0, iso-C_16:0, iso-C_17:0, iso-C_17:0 ω9c, and iso-C_11:0 3-OH. Combined analysis of the 16S rRNA gene sequences, fatty acid profile, and results from physiological and biochemical tests indicated that there is genotypic and phenotypic differentiation of the isolate from other Luteimonas species. For these reasons, strain B9^T was proposed as a novel species, named Luteimonas aestuarii. The type strain of the new species is B9^T (= KCTC 22048^T, DSM 19680^T).     

Development of optical criteria to discriminate various types of highly turbid lake waters

Our aim was to refine the optical classification of turbid waters in order to improve the performance of water color algorithms. Bio-optical measurements and sampling of optically active substances were performed in highly turbid lakes Taihu, Chaohu, and Dianchi, and in Three Gorges reservoir in China. Based on strong correlations between trough depths of remote sensing reflectance (R _rs(λ)) near 680 nm (denoted as TD680) and the ratios of inorganic suspended matter (ISM) to total suspended matter (TSM) concentrations, an empirical model was developed for water classification. In the 400–900 nm spectral range, different correlations between R _rs(λ), TSM and chlorophyll a (Chla) concentrations indicate discrepancies among the following ISM/TSM ranges: ISM/TSM ≤ 0.5, 0.5 < ISM/TSM < 0.8, and ISM/TSM ≥ 0.8. Corresponding findings support an important conclusion that only high ISM/TSM ratios, usually above 0.5, and using the more sensitive and stable near infrared spectral range (730–820 nm), can assure good performances of the TSM remote sensing algorithms. Meanwhile, the particulate absorption a _p(λ) and scattering b _p(λ) were strongly influenced by different ranges of ISM/TSM ratios. Typically the a _p(675) peaks became more and more vague as ISM/TSM increased, and the b _p(λ) values first decreased and then increased with a marked inflexion at ISM/TSM ≈ 0.5. The TD680 threshold values were derived to discriminate three types of turbid waters, i.e., Type 1 (TD680 ≥ 0.0082 sr⁻¹), Type 2 (0.0082 sr⁻¹ > TD680 > 0 sr⁻¹), and Type 3 (TD680 ≤ 0 sr⁻¹). This study provides a promising tool for identifying various types of highly turbid waters, and is significant for the development of class-based algorithms of water color remote sensing.     

<Emphasis Type="Italic">Joostella atrarenae</Emphasis> sp. nov., a novel member of the <Emphasis Type="Italic">Flavobacteriaceae</Emphasis> originating from the black sea sand of Jeju Island

Strain M1-2^T was isolated from the black sand from the seashore of Jeju Island, Republic of Korea and was classified using a polyphasic taxonomic approach. Strain M1-2^T appeared as Gram-negative, motile rods that could grow in the presence of 1–10% (w/v) NaCl and at temperatures ranging from 4 to 37°C. This isolate has catalase and oxidase activity and hydrolyses aesculin, DNA and l-tyrosine. Based on phylogenetic analysis using 16S rRNA gene sequences, strain M1-2^T belongs to the genus Joostella and is clearly distinct from the other described species of this genus, Joostella marina (type strain En5^T). The 16S rRNA gene sequence similarity level between M1-2^T and J. marina En5^T is 97.2%, and the DNA–DNA relatedness value between the two strains is 23.9%. Strain M1-2^T contains MK-6 as the major menaquinone and iso-C_15:0, summed feature 3 (C_16:1 ω7c and/or iso-C_15:0 2OH) and iso-C_17:0 3OH as major cellular fatty acids. The DNA G + C content is 32.3 mol%. These data suggest that strain M1-2^T should be classified as a novel species, for which the name Joostella atrarenae sp. nov. is proposed. The type strain for the novel species is M1-2^T (= KCTC 23194^T = NCAIM B.002413^T).     

<Emphasis Type="Italic">Alteromonas halophila</Emphasis> sp. nov., a new moderately halophilic bacterium isolated from a sea anemone

A pale yellow-colored, moderately halophilic, Gram-negative, catalase- and oxidase-positive, non-sporulating, rod-shaped, motile, aerobic bacterium, designated strain JSM 073008^T, was isolated from a sea anemone (Anthopleura xanthogrammica) collected from Naozhou Island, Leizhou Bay, South China Sea. The organism was able to grow with 1–20% (w/v) total salts (optimum, 5–10%), at pH 6.0–10.0 (optimum, pH 7.5) and 10–40°C (optimum, 25–30°C). The major cellular fatty acids were C_16:0, C_16:1 ω7c/iso-C_15:0 2-OH and C_18:1 ω7c. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid. The predominant respiratory quinone was Q-8 and the genomic DNA G + C content was 47.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 073008^T should be assigned to the genus Alteromonas, being most closely related to Alteromonas hispanica F-32^T (sequence similarity 96.9%), followed by Alteromonas genovensis LMG 24078^T (96.6%) and Alteromonas litorea TF-22^T (96.4%). The sequence similarities between the novel isolate and the type strains of other recognized Alteromonas species ranged from 95.9% (with Alteromonas stellipolaris ANT 69a^T) to 94.5% (with Alteromonas simiduii BCRC 17572^T). The combination of phylogenetic analysis, phenotypic characteristics and chemotaxonomic data supported the view that strain JSM 073008^T represents a new species of the genus Alteromonas, for which the name Alteromonas halophila sp. nov. is proposed. The type strain is JSM 073008^T (=CCTCC AA 207035^T = KCTC 22164^T). The authors Yi-Guang Chen and Huai-Dong Xiao have contributed equally to this work.