Design,synthesis, and neuroprotective effects of a dimeric dipeptide mimetic of the third loop of the nerve growth factor

Previously, we prepared dimeric dipeptide mimetics of the first and the fourth loops of the nerve growth factor (NGF): hexamethylenediamides of bis(N-aminocaproyl-glycyl-L-lysine) (GK-6) and bis(N-monosuccinyl-L-glutamyl-L-lysine) (GK-2). Both mimetics activated TrkA-receptors, but induced different postreceptor signal pathways. GK-2 selectively activated PI3K/AKT, whereas GK-6 activated both PI3K/AKT and MAPK/ERK. Both mimetics exhibited a neuroprotective activity. In this study, we continued the investigation of a contribution of separate loop-like structures in the NGF functions and created and studied dimeric dipeptide mimetics based on a beta-turn of the NGF third loop: hexamethylenediamides of bis(N-gamma-hydroxybutyryl-L-lysyl-L-histidine) (GTS-115) and bis(N-acetyl-L-lysyl-L-histidine) (GTS-113). GTS-115 was shown to exhibit the neuroprotective activity in the concentration range from 10^–5 to 10^–7 М towards the HT-22 cell culture under the conditions of oxidative stress. The acetyl-containing GTS-113 mimetic proved to be inactive. GTS-115 (1 mg/kg/day intraperitoneally, for 7 days, the administration was started 4 h after the operation) exhibited the neuroprotective properties and decreased the infarction volume by 25% on the model of a stroke that was induced by a transient occlusion of the medial cerebral artery of rats. The action mechanism of GTS-115 was studied by Western-blot analysis and this mimetic in a concentration of 10^–6 М was shown to activate the TrkA-receptor and both MAPK/ERK and PI3K/AKT basic postreceptor signal pathways. The inhibitory analysis revealed different contributions of these pathways into the GTS-115 neuroprotective effect. The LY294002 selective inhibitor of PI3K completely blocked the neuroprotective effect of GTS-115 in vitro, whereas the PD98059 specific inhibitor of MEK1 and MEK2 decreased this effect only by 10–15%. GTS-115 peptide stimulated a differentiation of the PC12 cells and caused a hyperalgesia in rats. These facts were in a good agreement with the literature data on the participation of the MAP-kinase pathway in these effects. Thus, the third NGF loop and the neighboring first NGF loop activated the postreceptor pathways in a similar way and exhibited the similar activities.     

Heterotrophic activity of bacterioplankton along the gradients of the chlorophyll <Emphasis Type="Italic">a</Emphasis> concentration and water temperature in marine and limnetic ecosystems

The dependence of the heterotrophic activity of bacterioplankton (V, μg C L^–1 h^–1) on the concentration of chlorophyll a (Chl, μg L^–1) and the water temperature (T) was examined for lakes (37°29′–80°36′ N) and marine polar waters (69°16′–80°36′ N). It was shown that ~76% of the V variations was related to changes in Chl and T.     

Effect of transcutaneous electrical spinal cord stimulation on the blood flow in the skin of lower limbs

Changes in the blood flow in the skin of the plantar surface of the hallux were investigated by laser Doppler flowmetry in eight healthy subjects during transcutaneous electrical spinal cord stimulation (tESCS) with the pulse parameters used to activate locomotion. Continuous tESCS in the area of C5–C6 vertebrae did not cause significant changes in the blood flow, while electrical stimulation at T ₁₂–T ₁ and L ₁–L ₂ levels resulted in an increase in skin perfusion by 22–27%. Wavelet analysis of microcirculatory fluctuations showed that tESCS induced flaxomotions in the range of sensory peptidergic fibers and enhanced the amplitude of fluctuations of microcirculation in the endothelium-dependent range. These results suggest that tESCS stimulates microcirculation in the skin mainly due to antidromic stimulation of sensory peptidergic nerve fibers, which promotes activity of microvascular endothelium, vasodilator secretion, a decrease in vascular resistance, and an increase in microcirculation.     

Cryopreservation of <Emphasis Type="Italic">Citrus</Emphasis> anthers in the National Crop Genebank of China

Genebank conservation of pollen is valuable because it makes genetic resources immediately available for use in breeding programs. In the case of Citrus species, conserved anthers or pollen can be easily transported and used to develop new varieties with pathogen resistance and desirable quality and yield traits. The aim of this study was to develop and improve air-desiccation cryopreservation protocols for Citrus cavaleriei and Citrus maxima anthers in genebanks. In the current study, warming, rehydration, and in vitro germination conditions were optimized to achieve high levels of in vitro germination in Citrus pollen for ten cultivars after liquid nitrogen (LN) exposure. The optimal warming, rehydration, and in vitro germination medium formulations affected the germination levels after pollen cryopreservation, with species- and cultivar-dependent effects. The Citrus anthers were dehydrated to the moisture content of 5–14% before LN exposure and warmed at 25 (cryopreserved Citrus anthers with a moisture content of lower than 10%) or 37°C (a moisture content of 10% or higher), then rehydrated, and cultured on medium with 150-g L^?1 sucrose, 0.1-g L^?1 boric acid, 1.0-g L^?1 calcium nitrate, 0.1-g L^?1 potassium nitrate, 0.3-g L^?1 magnesium sulfate, and 10-g L^?1 agar. After 2 yr of storage, in vitro germination levels of Citrus pollen after cryopreservation were significantly higher (> 22% for all ten cultivars) than those of samples that were stored at 4°C (0%). In vitro germination levels of pollen from six of ten cultivars after cryopreservation remained relatively high after 2 yr of storage (38–93%). The highest viability of 93% was obtained for C. cavaleriei ‘2–3’. The methods identified in the current study could be used to cryopreserve C. cavaleriei and C. maxima anthers.     

Decolorization of textile dye RB19 using volcanic rock matrix immobilized <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> cells with surface displayed laccase

A triplicate volcanic rock matrix–Bacillus thuringiensis–laccase WlacD (VRMs–Bt–WlacD) dye decolorization system was developed. WlacD was displayed on the B. thuringiensis MB174 cell surface to prepare a whole-cell laccase biocatalyst by using two repeat N-terminal domains of autolysin Mbg (Mbgn)₂ as the anchoring motif. Immunofluorescence microscopic assays confirmed that the fusion protein (Mbgn)₂–WlacD was anchored on the surface of the recombinant B. thuringiensis MB174. After optimization by a single factor test, L ₉(3⁴)-orthogonal test, Plackett–Burman test, steepest ascent method, and Box–Behnken response surface methodology, the whole-cell specific laccase activity of B. thuringiensis MB174 was improved to 555.2 U L^?1, which was 2.25 times than that of the primary culture condition. Optimized B. thuringiensis MB174 cells were further adsorbed by VRMs to prepare VRMs–Bt–WlacD, an immobilized whole-cell laccase biocatalyst. Decolorization capacity of as-prepared VRMs–Bt–WlacD toward an initial concentration of 500 mg L^?1 of an textile dye reactive blue 19 (RB19) aqueous solution reached 72.36% at a solid-to-liquid ratio of 10 g–100 mL. Repeated decolorization-activation operations showed the high decolorization capacity of VRMs–Bt–WlacD and have the potential for large-scale or continuous operations.     

Iron chelator deferiprone rescues memory deficits,hippocampal BDNF levels and antioxidant defenses in an experimental model of memory impairment

Brain-derived neurotrophic factor (BDNF) plays a key role in neural development and physiology, as well as in pathological states. Post-mortem studies demonstrate that BDNF is reduced in the brains of patients affected by neurodegenerative diseases. Iron accumulation has also been associated to the pathogenesis of neurodegenerative diseases. In rats, iron overload induces persistent memory deficits, increases oxidative stress and apoptotic markers, and decreases the expression of the synaptic marker, synaptophysin. Deferiprone (DFP) is an oral iron chelator used for the treatment of systemic iron overload disorders, and has recently been tested for Parkinson’s disease. Here, we investigated the effects of iron overload on BDNF levels and on mRNA expression of genes encoding TrkB, p75^NTR, catalase (CAT) and NQO1. We also aimed at investigating the effects of DFP on iron-induced impairments. Rats received iron or vehicle at postnatal days 12–14 and when adults, received chronic DFP or water (vehicle). Recognition memory was tested 19 days after the beginning of chelation therapy. BDNF measurements and expression analyses in the hippocampus were performed 24 h after the last day of DFP treatment. DFP restored memory and increased hippocampal BDNF levels, ameliorating iron-induced effects. Iron overload in the neonatal period reduced, while treatment with DFP was able to rescue, the expression of antioxidant enzymes CAT and NQO1.     

<Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> as a Probiotic Potential from Kouzeh Cheese (Traditional Iranian Cheese) and Its Antimicrobial Activity

The aim of this study is to isolate and identify Lactobacillus plantarum isolates from traditional cheese, Kouzeh, and evaluate their antimicrobial activity against some food pathogens. In total, 56 lactic acid bacteria were isolated by morphological and biochemical methods, 12 of which were identified as Lactobacillus plantarum by biochemical method and 11 were confirmed by molecular method. For analyzing the antimicrobial activity of these isolates properly, diffusion method was performed. The isolates were identified by 318 bp band dedicated for L. plantarum. The isolated L. plantarum represented an inhibitory activity against four of the pathogenic bacteria and showed different inhibition halos against each other. The larger halos were observed against Staphylococcus aureus and Staphylococcus epidermidis (15 ± 0.3 and 14.8 ± 0.7 mm, respectively). The inhibition halo of Escherichia coli was smaller than that of other pathogen and some L. plantarum did not show any inhibitory activity against E. coli, which were resistant to antimicrobial compounds produced by L. plantarum. The isolated L. plantarum isolates with the antimicrobial activity in this study had strong probiotic properties. These results indicated the nutritional value of Kouzeh cheese and usage of the isolated isolates as probiotic strains.     

Endonuclease Activity of MutL Protein of the <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis> Mismatch Repair System

We have purified the MutL protein from Rhodobacter sphaeroides mismatch repair system (rsMutL) for the first time. rsMutL demonstrated endonuclease activity in vitro, as predicted by bioinformatics analysis. Based on the alignment of 1483 sequences of bacterial MutL homologs with presumed endonuclease activity, conserved functional motifs and amino acid residues in the rsMutL sequence were identified: five motifs comprising the catalytic site responsible for DNA cleavage were found in the C–terminal domain; seven conserved motifs involved in ATP binding and hydrolysis and specific to the GHKL family of ATPases were found in the N–terminal domain. rsMutL demonstrated the highest activity in the presence of Mn²⁺. The extent of plasmid DNA hydrolysis declined in the row Mn²⁺ > Co²⁺ > Mg²⁺ > Cd²⁺; Ni²⁺ and Ca²⁺ did not activate rsMutL. Divalent zinc ions inhibited rsMutL endonuclease activity in the presence of Mn²⁺ excess. ATP also suppressed plasmid DNA hydrolysis by rsMutL. Analysis of amino acid sequences and biochemical properties of five studied bacterial MutL homologs with endonuclease activity revealed that rsMutL resembles the MutL proteins from Neisseria gonorrhoeae and Pseudomonas aeruginosa.     

<Emphasis Type="Italic">Paenibacillus bryophyllum</Emphasis> sp. nov., a nitrogen-fixing species isolated from <Emphasis Type="Italic">Bryophyllum pinnatum</Emphasis>

A nitrogen-fixing, endospore-forming bacterium, designated strain L201^T was isolated from the leaves of Bryophyllum pinnatum growing in South China Agricultural University. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain L201^T is affiliated with the genus Paenibacillus, and closely related to Paenibacillus albidus Q4-3^T (97.4%), Paenibacillus odorifer DSM 15391^T (97.3%) and Paenibacillus borealis DSM 13188^T (97.2%). The main fatty acids components was anteiso-C_15:0 (48.1%). The predominant isoprenoid quinone was MK-7. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The G+C content of strain L201^T was 43.9%. DNA–DNA relatedness between L201^T and the reference strain was 29.8%. Biological and biochemical tests, protein patterns, genomic DNA fingerprinting and comparison of cellular fatty acids distinguished strain L201^T from the closely related Paenibacillus species. Based on these data, the novel species Paenibacillus bryophyllum sp. nov. is proposed, with the type strain L201^T(=?KCTC 33951 ^T?=?GDMCC 1.1251 ^T).     

Proteasome properties of hemocytes differ between the whiteleg shrimp <Emphasis Type="Italic">Penaeus vannamei</Emphasis> and the brown shrimp <Emphasis Type="Italic">Crangon crangon</Emphasis> (Crustacea,Decapoda)

Crustaceans are intensively farmed in aquaculture facilities where they are vulnerable to parasites, bacteria, or viruses, often severely compromising the rearing success. The ubiquitin-proteasome system (UPS) is crucial for the maintenance of cellular integrity. Analogous to higher vertebrates, the UPS of crustaceans may also play an important role in stress resistance and pathogen defense. We studied the general properties of the proteasome system in the hemocytes of the whiteleg shrimp, Penaeus vannamei, and the European brown shrimp Crangon crangon. The 20S proteasome was the predominant proteasome population in the hemocytes of both species. The specific activities of the trypsin-like (Try-like), chymotrypsin-like (Chy-like), and caspase-like (Cas-like) enzymes of the shrimp proteasome differed between species. P. vannamei exhibited a higher ratio of Try-like to Chy-like activities and Cas-like to Chy-like activities than C. crangon. Notably, the Chy-like activity of P. vannamei showed substrate or product inhibition at concentrations of more than 25 mmol L^?1. The K _M values ranged from 0.072 mmol L^?1 for the Try-like activity of P. vannamei to 0.309 mmol L^?1 for the Cas-like activity of C. crangon. Inhibition of the proteasome of P. vannamei by proteasome inhibitors was stronger than in C. crangon. The pH profiles were similar in both species. The Try-like, Chy-like, and Cas-like sites showed the highest activities between pH 7.5 and 8.5. The proteasomes of both species were sensitive against repeated freezing and thawing losing ~80–90% of activity. This study forms the basis for future investigations on the shrimp response against infectious diseases, and the role of the UPS therein.     

Bioactive M(II) complexes of amino acid-based N<Subscript>3</Subscript>O donor mixed ligand: in vitro and in silico DNA binding studies

Three novel mixed ligand M(II) complexes, namely [CoL¹L²Cl₂] (1), [CuL¹L²Cl₂] (2), and [ZnL¹L²Cl₂] (3), were synthesized using 1,4-naphthoquinone, L-histidine, and 1,10-phenanthroline as ligands. The ligand framework and the corresponding structural changes on complexation were ascertained based on the results of elemental analysis, conductivity measurements, magnetic behavior, FT-IR, UV-visible, ¹H NMR, ¹³C NMR, ESR spectral studies, and ESI mass spectrometry. The biological action of the ligand (L) and complexes 1–3 such as DNA binding and cleaving ability were studied. Results suggest that the ligand and the complexes could interact with calf thymus-DNA (CT-DNA) via intercalation mode. Additionally, complex 2 displayed potential antioxidant activity in in vitro studies. Docking simulation was performed to position the ligand and the complexes into the active site of BDNA (IBNA) to determine the probable binding mode.     

Interaction of the synthetic immunomodulatory dipeptide bestim with murine macrophages and thymocytes

The tritium-labeled dipeptide bestim (γ-D-Glu-L-Trp) with a specific activity of 45 Ci/mmol was obtained by high-temperature solid-state catalytic isotope exchange. It was found that [³H]bestim binds with a high affinity to murine peritoneal macrophages (K _d 2.1 ± 0.1 nM) and thymocytes (K _d 3.1 ± 0.2 nM), as well as with plasma membranes isolated from these cells (K _d 18.6 ± 0.2 and 16.7 ± 0.3 nM, respectively). The specific binding of [³H]bestim to macrophages and thymocytes was inhibited by the unlabeled dipeptide thymogen (L-Glu-L-Trp) (K _i 0.9 ± 0.1 and 1.1 ± 0.1 nM, respectively). After treatment with trypsin, macrophages and thymocytes lost the ability to bind [³H]bestim. Bestim in the concentration range of 10^?10 to 10^?6 M reduced the adenylate cyclase activity in the membranes of murine macrophages and thymocytes.     

Variation at Two Loci affecting Homoeologous Meiotic Chromosome Pairing in <Emphasis Type="Italic">Triticum aestivum</Emphasis> × <Emphasis Type="Italic">Aegilops mutica</Emphasis> Hybrids

HOMOEOLOGOUS chromosomes of the three genomes of bread wheat (Triticum aestivum 2n=6x=42) are normally prevented from pairing at meiosis by the activity of an allele at the Ph locus on chromosome 5B^L (refs. 1–4). This activity is responsible for the regular bivalent-forming meiotic behaviour and for the stable disomic inheritance of T. aestivum. If allelic variation occurs at the PA locus in nature it is extremely rare, although mutation has been induced and mutant alleles isolated^3,4.     

Solution of Levinthal’s paradox is possible at the level of the formation and assembly of protein secondary structures

The complete volume of a protein’s conformation space is smaller by many orders of magnitude at the level of secondary-structure elements as compared with the conformation of amino-acid residues. According to Levinthal’s estimate, the latter is ~10^2L, with L being the number of residues in the chain, while the former, at the level of secondary structures, increases no faster than ~L^N with N being the number of the secondary-structure elements. N is approximately L/15 according to the statistics of protein structures. This drastic decrease in the exponent (L/15 instead of 2L) considerably reduces the sampling space and explains the reason that sampling of the conformation space at the level of secondary-structure elements does not prevent the protein chain from finding its most stable structure.     

Lima bean nodulates efficiently with <Emphasis Type="Italic">Bradyrhizobium</Emphasis> strains isolated from diverse legume species

Lima bean (Phaseolus lunatus L.) is an important legume species that establishes symbiosis with rhizobia, mainly of the Bradyrhizobium genus. The aim of this study was to evaluate the efficiency of rhizobia of the genus Bradyrhizobium in symbiosis with lima bean, in both Leonard jars and in pots with a Latossolo Amarelo distrófico (Oxisol). In the experiment in Leonard jars, 17 strains isolated from nodules of the three legume subfamilies, Papilionoideae (Vigna unguiculata, Pterocarpus sp., Macroptilium atropurpureum, Swartzia sp., and Glycine max), Mimosoideae (Inga sp.), and Caesalpinioideae (Campsiandra surinamensis) and two uninoculated controls, one with a low concentration (5.25 mg L^?1) and another with a high concentration (52.5 mg L^?1) of mineral nitrogen (N) were evaluated. The six strains that exhibited the highest efficiency in Leonard jars, isolated from nodules of Vigna unguiculata (UFLA 03–144, UFLA 03–84, and UFLA 03–150), Campsiandra surinamensis (INPA 104A), Inga sp. (INPA 54B), and Swartzia sp. (INPA 86A), were compared to two uninoculated controls, one without and another with 300 mg N dm^?3 (NH₄NO₃) applied to pots with samples of an Oxisol in the presence and absence of liming. In this experiment, liming did not affect nodulation and plant growth; the INPA 54B and INPA 86A strains stood out in terms of shoot dry matter production and provided increases of approximately 48% in shoot N accumulation compared to the native rhizobia populations. Our study is the first to indicate Bradyrhizobium strains isolated from the three legume subfamilies are able to promote lima bean growth via biological nitrogen fixation in soil conditions.     

Photosynthetic activity of the phytoplankton in the reservoirs of the Volga River

The parameters of the photosynthetic activity per unit of the phytoplankton biomass have been studied for the reservoirs of the Volga River. The wide range of variability is accompanied by most of the values of A/B ratio laying within 0.5–3 mg O₂/(mg · day); the P/B ratio in the photic layer varies as 0.5–3 day^–1 and in the whole water column varies as 1 day^-1. The maximal values have been observed for the reservoirs located in the Upper Volga River. The turnover period of the phytoplankton biomass in the photic zone of the studied reservoirs was 0.2–1.6 day, or in2.1–3.8 times higher than for the whole water column from the surface down to the bottom. The seasonal variability of the A/B and P/B ratios in each reservoir had more pronounced individual variability than the variability observed for the whole cascade during the summer season. The A/B and P/B ratios decrease significantly in the oligotrophic waters to the eutrophic; these ratios have an indicator value.     

Biodegradation of the Pyrethroid Pesticide Esfenvalerate by Marine-Derived Fungi

Esfenvalerate biodegradation by marine-derived fungi is reported here. Esfenvalerate (S,S-fenvalerate) and its main metabolites [3-phenoxybenzaldehyde (PBAld), 3-phenoxybenzoic acid (PBAc), 3-phenoxybenzyl alcohol (PBAlc), and 2-(4-chlorophenyl)-3-methylbutyric acid (CLAc)] were quantitatively analyzed by a validated method in triplicate experiments. All the strains (Penicillium raistrickii CBMAI 931, Aspergillus sydowii CBMAI 935, Cladosporium sp. CBMAI 1237, Microsphaeropsis sp. CBMAI 1675, Acremonium sp. CBMAI 1676, Westerdykella sp. CBMAI 1679, and Cladosporium sp. CBMAI 1678) were able to degrade esfenvalerate, however, with different efficiencies. Initially, 100 mg L^?1 esfenvalerate (Sumidan 150SC) was added to each culture in 3 % malt liquid medium. Residual esfenvalerate (64.8–95.2 mg L^?1) and the concentrations of PBAc (0.5–7.4 mg L^?1), ClAc (0.1–7.5 mg L^?1), and PBAlc (0.2 mg L^?1) were determined after 14 days. In experiments after 7, 14, 21, and 28 days of biodegradation with the three most efficient strains, increasing concentrations of the toxic compounds PBAc (2.7–16.6 mg L^?1, after 28 days) and CLAc (6.6–13.4 mg L^?1, after 28 days) were observed. A biodegradation pathway was proposed, based on HPLC-ToF results. The biodegradation pathway includes PBAld, PBAc, PBAlc, ClAc, 2-hydroxy-2-(3-phenoxyphenyl)acetonitrile, 3-(hydroxyphenoxy)benzoic acid, and methyl 3-phenoxy benzoate. Marine-derived fungi were able to biodegrade esfenvalerate in a commercial formulation and showed their potential for future bioremediation studies in contaminated soils and water bodies.     

Enhancing carotenoid production in <Emphasis Type="Italic">Rhodotorula mucilaginosa</Emphasis> KC8 by combining mutation and metabolic engineering

Rhodotorula mucilaginosa has been considered as a potential industrial yeast due to its unicellular and fast-growing characteristics, and its ability to produce carotenoids, including torularhodin. However, its low total carotenoid production limits its commercial application. In this study, mutation breeding and metabolic engineering were employed to enhance carotenoid production in the R. mucilaginosa strain KC8. After chemical–physical mutagenesis, R. mucilaginosa K4 with a 67% greater concentration of carotenoids (14.47 ± 0.06 mg L^?1) than R. mucilaginosa KC8 (8.67 ± 0.07 mg L^?1) was obtained. To further enhance carotenoid production, gene HMG1 encoding the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was introduced from another yeast, Saccharomyces cerevisiae, and overexpressed in R. mucilaginosa K4. The carotenoid production of HMG1-gene-overexpression transformant G1 reached 16.98 mg L^?1. To relieve the feedback inhibition of ergosterol, and to down-regulate ergosterol synthesis, ketoconazole, an ergosterol synthesis inhibitor, was added at a concentration of 28 mg L^?1. The carotenoid production of the transformant G1 reached 19.14 ± 0.09 mg L^?1, which was 121% higher than in R. mucilaginosa KC8. This suggests that a combination of chemical–physical mutagenesis, overexpression of the HMG1 gene, and adding ketoconazole is an effective strategy to improve carotenoid production.     

<Emphasis Type="Italic">Deinococcus sedimenti</Emphasis> sp. nov. isolated from river sediment

A novel Gram-positive, oval-shaped, non-motile bacterium designated strain 16F1L^T was isolated from sediment collected from the Han River in Seoul, Republic of Korea. Based on the 16S rRNA gene sequence (1,448 bp), this strain was identified as a member of the genus Deinococcus that belongs to the class Deinococci. Similarities in the 16S rRNA gene sequence were shown with Deinococcus daejeonensis MJ27^T (99.0%), D. grandis DSM 3963^T (98.1%), D. radiotolerans C1^T (97.5%), and D. caeni Ho-08^T (97.2%). Strain 16F1L^T was classified as a different genomic species from closely related Deinococcus members, based on less than 70% DNA-DNA relatedness. Genomic DNA G+C content of strain 16F1L^T was 67.2 mol%. Strain 16F1L^T was found to grow at temperatures of 10–37°C (optimum 25°C) and pH 7–8 (optimum pH 7) on R2A medium, and was catalase-positive and oxidase-negative. Strain 16F1L^T showed resistance to gamma radiation (D₁₀ > 2 kGy). In addition, this strain had the following chemotaxonomic characteristics: the major fatty acids were C_15:1ω6c and C_16:1ω7c; the polar lipid profile contained phosphoglycolipids, unknown aminophospholipids, an unknown aminoglycolipid, unknown aminolipids, an unknown glycolipid, an unknown phospholipid, and an unknown polar lipid; the major quinone was MK-8. Phylogenetic, genotypic, phenotypic, and chemotaxonomic characteristics indicated that strain 16F1L^T represents a novel species within the genus Deinococcus, for which the name Deinococcus sedimenti sp. nov. is proposed. The type strain is 16F1L^T (=KCTC 33796^T =JCM 31405^T).     

Root-derived bicarbonate assimilation in response to variable water deficit in <Emphasis Type="Italic">Camptotheca acuminate</Emphasis> seedlings

Water deficit is one of the key factors that limits the carbon (C) assimilation and productivity of plants. The effect of variable water deficit on recently root-derived bicarbonate assimilation in Camptotheca acuminate seedlings was investigated. Three-month-old seedlings were subjected to three water regimes, well-watered (WW), moderate stress (MS), and severe stress (SS) induced by polyethyleneglycol, in conjunction with relatively high (H) and low (L) natural ¹³C-abundance of NaHCO₃-labeled treatments in hydroponics for 14 days. The δ¹³C of the newly expanded leaves in H were generally more enriched in heavy isotopes than were those in L, indicative of the involvement of bicarbonate in aboveground tissues. The C isotope fractionation of newly expanded leaves relative to air (?¹³C_air-leaves) ranged from 17.78 to 21.78‰ among the treatments. The ?¹³C_air-leaves under the MS and SS treatments in H were both more negative than was that in L. A linear regression between Ci/Ca and ?¹³C_air-leaves in both L and H were different from the theoretical regression. On the basis of the two end-member mixing model, the proportion of fixed CO₂ supplied from bicarbonate contributing to the total photosynthetically inorganic C assimilation were 10.34, 20.05 and 16.60% under the WW, MS, and SS treatments, respectively. These results indicated that the increase in water deficit decreased the atmospheric CO₂ gain but triggered a compensatory use of bicarbonate in C. acuminate seedlings.