Long-term H<Subscript>2</Subscript> photoproduction from starch by co-culture of <Emphasis Type="Italic">Clostridium butyricum</Emphasis> and <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis> in a repeated batch process

Objectives

To prove the possibility of efficient starch photofermentation in co-culture of heterotrophic and phototrophic bacteria over prolonged period.

Results

Repeated batch photofermentation of starch was demonstrated in co-culture Clostridium butyricum and Rhodobacter sphaeroides under microaerobic conditions. It continued 15 months without addition of new inoculum or pH regulation when using 4–5 g starch l^?1 and 0.04 g yeast extract l^?1. The complete degradation of starch without volatile fatty acids accumulation was shown in this co-culture. The average H₂ yield of 5.2 mol/mol glucose was much higher than that in Clostridium monoculture. The species composition of co-culture was studied by q-PCR assay. The concentration of Clostridium cells in prolonged co-culture was lower than in monoculture and even in a single batch co-culture. This means that Clostridia growth was significantly limited whereas starch hydrolysis still took place.

Conclusion

The prolonged repeated batch photofermentation of starch by co-culture C. butyricum and R. sphaeroides provided efficient H₂ production without accumulation of organic acids under conditions of Clostridia limitation.

     

Genome-wide analysis of across herd <Emphasis Type="Italic">F</Emphasis> <Subscript>st</Subscript> Heterogeneity in holsteinized cattle

To form a reference population necessary for genomic selection of dairy cattle, it is important to acquire information on the genetic diversity of the base population. Our report is the first among the studies on breeding of farm animals to implement Wright’s F-statistics for this purpose. Genotyping of animals was performed using BovineSNP50 chip. In total, we genotyped 499 heifers from 13 breeding farms in the Leningrad region. We calculated Weir and Cockerham’s F_st estimate for all pairwise combinations of herds from breeding farms and the values obtained were in the range of 0.016–0.115 with the mean of 0.076 ± 0.002. Theoretical F_st values for the same pairwise combinations of herds were calculated using the ADMIXTURE program. These values were significantly (P < 0.05) higher than Weir and Cockerham’s F_st estimates and fell in the range of 0.063–0.136 with the mean of 0.100 ± 0.001. We discuss the reasons for this discrepancy between the two sets of F_st data. The obtained F_st values were used to identify reliable molecular-genetical differences between the herds. The ADMIXTURE program breaks the pool of 476 heifers into 16 subpopulations, the number of which is close to the number of herds used in the experiment. Results of the comparison between F_st values obtained using SNP markers with published data obtained on microsatellites are in support of the common opinion that microsatellite analysis results in underestimation of F_st values. On the whole, the obtained across-herd F_st values are in the range Fst data reported for cattle breeds. Results of comparison of F_st values with the data on the origin of bulls imported from different countries lead to the conclusion on the expediency of the use of F_st data to assess heterogeneity of the herds. Thus, we have demonstrated that use of F_st data provides the means to assess genetic diversity of cattle herds and is a necessary step in the formation of a reference population for dairy cattle.     

The Effects of Low Doses of Gamma-Radiation on Growth and Membrane Activity of <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> GRP3 and <Emphasis Type="Italic">Escherichia coli</Emphasis> M17

Microorganisms are part of the natural environments and reflect the effects of different physical factors of surrounding environment, such as gamma (γ) radiation. This work was devoted to the study of the influence of low doses of γ radiation with the intensity of 2.56?μW (m²?s)^?1 (absorbed doses were 3.8 mGy for the radiation of 15?min and 7.2 mGy—for 30?min) on Escherichia coli M-17 and Pseudomonas aeruginosa GRP3 wild type cells. The changes of bacterial, growth, survival, morphology, and membrane activity had been studied after γ irradiation. Verified microbiological (specific growth rate, lag phase duration, colony-forming units (CFU) number, and light microscopy digital image analysis), biochemical (ATPase activity of bacterial membrane vesicles), and biophysical (H⁺ fluxes throughout cytoplasmic membrane of bacteria) methods were used for assessment of radiation implications on bacteria. It was shown that growth specific rate, lag phase duration and CFU number of these bacteria were lowered after irradiation, and average cell surface area was decreased too. Moreover ion fluxes of bacteria were changed: for P. aeruginosa they were decreased and for E. coli—increased. The N,N′-dicyclohexylcarbodiimide (DCCD) sensitive fluxes were also changed which were indicative for the membrane-associated F₀F₁-ATPase enzyme. ATPase activity of irradiated membrane vesicles was decreased for P. aeruginosa and stimulated for E. coli. Furthermore, DCCD sensitive ATPase activity was also changed. The results obtained suggest that these bacteria especially, P. aeruginosa are sensitive to γ radiation and might be used for developing new monitoring methods for estimating environmental changes after γ irradiation.     

Flubendiamide affects visual and locomotory activities of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> for three successive generations (P,F<Subscript>1</Subscript> and F<Subscript>2</Subscript>)

Flubendiamide is widely used in agricultural fields to exterminate a broad spectrum of pests (lepidopteran insects) by disrupting their muscle function. The main objective of this study was to find the effects of flubendiamide on a non-target organism, Drosophila melanogaster (dipteran insect). In the present study, different sub-lethal concentrations of Flubendiamide caused a significant (P?<?0.05) decrease in acetylcholinesterase activity and increase in cytochrome P450 activity in adult D. melanogaster. Phototaxis and climbing behaviours were found to significantly (P?<?0.05) alter in exposed flies. The observed alteration in phototaxis and climbing behaviours were not restricted to P generation, but were found to be transmitted to subsequent generations (F₁ and F₂ generation) that had never been directly exposed to the test chemical during their life time. It is only their predecessors (P generation) who have been affronted with different concentrations of Flubendiamide. Humans and Drosophilids share almost 60% genomic similarity and 75% disease gene resemblance. Moreover, most of the circuits governing the behaviours studied involve the inhibition and excitation of neurotransmitters, which are conserved in humans and flies. Thus, the present findings suggest that chronic flubendiamide exposure might induce alteration in neurotransmission leading to discrepancy in the behavioural responses (vision and flight) in other beneficial insects and insect-dependent organisms.     

Bonding,aromaticity, and planar tetracoordinated carbon in Si<Subscript>2</Subscript>CH<Subscript>2</Subscript> and Ge<Subscript>2</Subscript>CH<Subscript>2</Subscript>

Natural bond orbital (NBO) analyses and dissected nucleus-independent chemical shifts (NICS _{π z z} ) were computed to evaluate the bonding (bond type, electron occupation, hybridization) and aromatic character of the three lowest-lying Si₂CH₂ (1-Si, 2-Si, 3-Si) and Ge₂CH₂ (1-Ge, 2-Ge, 3-Ge) isomers. While their carbon C₃H₂ analogs favor classical alkene, allene, and alkyne type bonding, these Si and Ge derivatives are more polarizable and can favor “highly electron delocalized”? and “non-classical”? structures. The lowest energy Si ₂CH₂ and Ge ₂CH₂ isomers, 1-Si and 1-Ge, exhibit two sets of 3–center 2–electron (3c-2e) bonding; a π-3c-2e bond involving the heavy atoms (C–Si–Si and C–Ge–Ge), and a σ-3c-2e bond (Si–H–Si, Ge–H–Ge). Both 3-Si and 3-Ge exhibit π and σ-3c-2e bonding involving a planar tetracoordinated carbon (ptC) center. Despite their highly electron delocalized nature, all of the Si₂CH₂ and Ge₂CH₂ isomers considered display only modest two π electron aromatic character (NICS(0) _{π z z} =--6.2 to –8.9 ppm, computed at the heavy atom ring center) compared to the cyclic-C ₃H₂ (–13.3 ppm).

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Graphical Abstract The three lowest Si2CH2 and Ge2CH2 isomers.

     

Spawning and fertility of F<Subscript>1</Subscript> hybrids of the coral genus <Emphasis Type="Italic">Acropora</Emphasis> in the Indo-Pacific

The role of hybridization through multi-specific synchronous spawning in the evolution of reef-building corals has been discussed since the 1990s, particularly for the genus Acropora. However, F₁ hybrids have been reported as common in only one case in the Caribbean, with no evidence of mechanisms that would allow continuous reproduction of the hybrids. In this study, we report for the first time the fecundity of two F₁ hybrid colonies produced experimentally from two Indo-Pacific species, A. intermedia and A. florida. These F₁ hybrids spawned at the same time as the parental corals. Backcrossing and F₁ hybrid crossing were successful in both directions. Furthermore, more than 90% self-fertilization was achieved in an F₁ hybrid, although it was negligible in the parental corals. While it is possible that the F₁ hybrid was a chimera, these results suggest that some products of interspecific hybridization may persist as the offspring of self-fertilizing F₁ hybrids.     

Discovery and introgression of the wild sunflower-derived novel downy mildew resistance gene <Emphasis Type="Italic">Pl</Emphasis><Subscript><Emphasis Type="Italic">19</Emphasis></Subscript> in confection sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis> L.)

Key message

A new downy mildew resistance gene, Pl ₁₉ , was identified from wild Helianthus annuus accession PI 435414, introduced to confection sunflower, and genetically mapped to linkage group 4 of the sunflower genome.

Abstract

Wild Helianthus annuus accession PI 435414 exhibited resistance to downy mildew, which is one of the most destructive diseases to sunflower production globally. Evaluation of the 140 BC₁F_2:3 families derived from the cross of CMS CONFSCLB1 and PI 435414 against Plasmopara halstedii race 734 revealed that a single dominant gene controls downy mildew resistance in the population. Bulked segregant analysis conducted in the BC₁F₂ population with 860 simple sequence repeat (SSR) markers indicated that the resistance derived from wild H. annuus was associated with SSR markers located on linkage group (LG) 4 of the sunflower genome. To map and tag this resistance locus, designated Pl ₁₉ , 140 BC₁F₂ individuals were used to construct a linkage map of the gene region. Two SSR markers, ORS963 and HT298, were linked to Pl ₁₉ within a distance of 4.7 cM. After screening 27 additional single nucleotide polymorphism (SNP) markers previously mapped to this region, two flanking SNP markers, NSA_003564 and NSA_006089, were identified as surrounding the Pl ₁₉ gene at a distance of 0.6 cM from each side. Genetic analysis indicated that Pl ₁₉ is different from Pl ₁₇ , which had previously been mapped to LG4, but is closely linked to Pl ₁₇ . This new gene is highly effective against the most predominant and virulent races of P. halstedii currently identified in North America and is the first downy mildew resistance gene that has been transferred to confection sunflower. The selected resistant germplasm derived from homozygous BC₂F₃ progeny provides a novel gene for use in confection sunflower breeding programs.

     

Co-cultivation of <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> with <Emphasis Type="Italic">Azotobacter chroococcum</Emphasis> improved H<Subscript>2</Subscript> production

Objectives

To improve H₂ production, the green algae Chlamydomonas reinhardtii cc849 was co-cultured with Azotobacter chroococcum.

Results

The maximum H₂ production of the co-culture was 350% greater than that of the pure algal cultures under optimal H₂ production conditions. The maximum growth and the respiratory rate of the co-cultures were about 320 and 300% of the controls, and the dissolved O₂ of co-cultures was decreased 74%. Furthermore, the in vitro maximum hydrogenase activity of the co-culture was 250% greater than that of the control, and the in vivo maximum hydrogenase activity of the co-culture was 1.4-fold greater than that of the control. In addition, the maximum starch content of co-culture was 1400% that of the control.

Conclusions

Azotobacter chroococcum improved the H₂ production of the co-cultures by decreasing the O₂ content and increasing the growth and starch content of the algae and the hydrogenase activity of the co-cultures relative to those of pure algal cultures.

     

Messenger Discriminating Species of Initiation Factor F<Subscript>3</Subscript>

Species of the polypeptide chain initiation factor F₃ with high selectivity toward either MS2 or T4 phage messenger RNAs have been isolated from normal E. coli cells.     

Biomanufacture of nano-Pd(0) by <Emphasis Type="Italic">Escherichia coli</Emphasis> and electrochemical activity of bio-Pd(0) made at the expense of H<Subscript>2</Subscript> and formate as electron donors

Objective

Palladised cells of Desulfovibrio desulfuricans and Shewanella oneidensis have been reported as fuel cell electrocatalysts but growth at scale may be unattractive/costly; we have evaluated the potential of using E. coli, using H₂/formate for Pd-nanoparticle manufacture.

Results

Using ‘bio-Pd’ made under H₂ (20 wt%) cyclic voltammograms suggested electrochemical activity of bio-NPs in a native state, attributed to proton adsorption/desorption. Bio-Pd prepared using formate as the electron donor gave smaller, well separated NPs; this material showed no electrochemical properties, and hence little potential for fuel cell use using a simple preparation technique. Bio-Pd on S. oneidensis gave similar results to those obtained using E. coli.

Conclusion

Bio-Pd is sufficiently conductive to make an E. coli-derived electrochemically active material on intact, unprocessed bacterial cells if prepared at the expense of H₂, showing potential for fuel cell applications using a simple one-step preparation method.

     

Transmission and characterization of <Emphasis Type="Italic">bla</Emphasis><Subscript>NDM-1</Subscript> in <Emphasis Type="Italic">Enterobacter cloacae</Emphasis> at a teaching hospital in Yunnan,China

Background

In recent years, New Delhi metallo-beta-lactamases 1 (bla _NDM-1) has been reported with increasing frequency and become prevalent. The present study was undertaken to investigate the epidemiological dissemination of the bla _NDM-1 gene in Enterobacter cloacae isolates at a teaching hospital in Yunnan, China.

Methods

Antimicrobial susceptibility testing was performed using VITEK 2 system and E test gradient strips. The presence of integrons and insertion sequence common region 1 were examined by PCR and sequencing. Clonal relatedness was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Conjugation experiments and Southern blot hybridization were performed to determine the transferability of plasmids.

Results

Ten E. cloacae isolates and their Escherichia coli transconjugants were exhibited similar resistant patterns to carbapenems, cephalosporins and penicillins. 8 (80%) of E. cloacae isolates carried class 1 integron and 1 (12.5%) carried class 2 integron. Integron variable regions harbored the genes which encoded resistance to aminoglycosides (aadA1, aadA2, aadA5, aadB, aac(6′)-Ib-cr), sulfamethoxazole/trimethoprim (dfrA17, dfrA12, dfrA15) and Streptozotocin (sat2). Six E. cloacae isolates belonged to ST74 and exhibited highly similar PFGE patterns. Each isolate shared an identical plasmid with ~33.3 kb size that carried the bla _NDM-1 gene, except T3 strain, of which the bla _NDM-1 gene was located on a ~50 kb plasmid.

Conclusions

Our findings suggested that plasmid was able to contribute to the dissemination of bla _NDM-1. Hence, more attention should be devoted to monitor the dissemination of the bla _NDM-1 gene due to its horizontal transfer via plasmid. In addition, nosocomial surveillance system should actively monitor the potential endemic clone of ST74 to prevent their further spread.

     

Natively oxidized amino acid residues in the spinach cytochrome <Emphasis Type="Italic">b</Emphasis><Subscript><Emphasis Type="Italic">6</Emphasis></Subscript><Emphasis Type="Italic">f</Emphasis> complex

The cytochrome b ₆ f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b ₆ f is 10–20 fold higher than that observed for the analogous respiratory cytochrome bc₁ complex. The types of ROS produced (O₂^{??, 1}O₂, and, possibly, H₂O₂) and the site(s) of ROS production within the b ₆ f complex have been the subject of some debate. Proposed sources of ROS have included the heme b _p , PQ _p ^?? (possible sources for O₂^??), the Rieske iron–sulfur cluster (possible source of O₂^?? and/or ¹O₂), Chl a (possible source of ¹O₂), and heme c _n (possible source of O₂^?? and/or H₂O₂). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b ₆ f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b ₆ f complex.     

Simple generalisation of a mesophyll resistance model for various intracellular arrangements of chloroplasts and mitochondria in C<Subscript>3</Subscript> leaves

The classical definition of mesophyll conductance (g _m) represents an apparent parameter (g _m,app) as it places (photo)respired CO₂ at the same compartment where the carboxylation by Rubisco takes place. Recently, Tholen and co-workers developed a framework, in which g _m better describes a physical diffusional parameter (g _m,dif). They partitioned mesophyll resistance (r _m,dif = 1/g _m,dif) into two components, cell wall and plasmalemma resistance (r _wp) and chloroplast resistance (r _ch), and showed that g _m,app is sensitive to the ratio of photorespiratory (F) and respiratory (R _d) CO₂ release to net CO₂ uptake (A): g _m,app = g _m,dif/[1?+?ω(F?+?R _d)/A], where ω is the fraction of r _ch in r _m,dif. We herein extend the framework further by considering various scenarios for the intracellular arrangement of chloroplasts and mitochondria. We show that the formula of Tholen et al. implies either that mitochondria, where (photo)respired CO₂ is released, locate between the plasmalemma and the chloroplast continuum or that CO₂ in the cytosol is completely mixed. However, the model of Tholen et al. is still valid if ω is replaced by ω(1?σ), where σ is the fraction of (photo)respired CO₂ that experiences r _ch (in addition to r _wp and stomatal resistance) if this CO₂ is to escape from being refixed. Therefore, responses of g _m,app to (F?+?R _d)/A lie somewhere between no sensitivity in the classical method (σ =1) and high sensitivity in the model of Tholen et al. (σ =0).     

Amino acid composition of leaf,grain and bracts of japonica rice (<Emphasis Type="Italic">Oryza Sativa</Emphasis> ssp. <Emphasis Type="Italic">japonica</Emphasis>) and its response to nitrogen fertilization

Heat stress is one of the main abiotic stresses that limit plant growth. The effects of high temperature on oxidative damage, PSII activity and D1 protein turnover were studied in three wheat varieties with different heat susceptibility (CS, YN949 and AK58). The results showed that heat stress induced lower lipid peroxidation in AK58 and YN949 than CS, which was related to different changes of SOD, CAT, POD and H₂O₂. Similarly, AK58 and YN949 performed better PSII photochemical efficiency (F_v/F_m, ΦPSII and ETR) under high temperature, which was attributed to rapid synthesis and degradation of D1 protein. Moreover, higher expression of D1 protein turnover-related genes (PsbA, STN8, PBCP, Deg1, Deg2, Deg5, Deg8, FtsH1/5 and FtsH2/8) and SOD activity in AK58 and YN949 under normal conditions also established a basis for acclimatizing high temperatures, thereby alleviating PSII photoinhibition and reducing oxidative damage when exposed to heat stress.     

Tight repulsion linkage between <Emphasis Type="Italic">Sr36</Emphasis> and <Emphasis Type="Italic">Sr39</Emphasis> was revealed by genetic,cytogenetic and molecular analyses

Key message

The shortening of Aegilops speltoides segment did not facilitate recombination between stem rust resistance genes Sr36 and Sr39 . Robustness of marker rwgs28 for marker-assisted selection of Sr39 was demonstrated.

Abstract

Stem rust resistance genes Sr39 and Sr36 were transferred from Aegilops speltoides and Triticum timopheevii, respectively, to chromosome 2B of wheat. Genetic stocks RL6082 and RWG1 carrying Sr39 on a large and a shortened Ae. speltoides segments, respectively, and the Sr36-carrying Australian wheat cultivar Cook were used in this study. This investigation was planned to determine the genetic relationship between these genes. Stem rust tests on F₃ populations derived from RL6082/Cook and RWG1/Cook crosses showed tight repulsion linkage between Sr39 and Sr36. The genomic in situ hybridization analysis of heterozygous F₃ family from the RWG1/Cook population showed that the translocated segments do not overlap. Meiotic analysis on the F₁ plant from RWG1/Cook showed two univalents at the metaphase and anaphase stages in a majority of the cells indicating absence of pairing. Since meiotic pairing has been reported to initiate at the telomere, pairing and recombination may be inhibited due to very little wheat chromatin in the distal end of the chromosome arm 2BS in RWG1. The Sr39-carrying large Ae. speltoides segment transmitted preferentially in the RL6082/Cook F₃ population, whereas the Sr36-carrying T. timopheevii segment over-transmitted in the RWG1/Cook cross. Genotyping with the co-dominant Sr39- and Sr36-linked markers rwgs28 and stm773-2, respectively, matched the phenotypic classification of F₃ families. The RWG1 allele amplified by rwgs28 was diagnostic for the shortened Ae. speltoides segment and alternate alleles were amplified in 29 Australian cultivars. Marker rwgs28 will be useful in marker-assisted pyramiding of Sr39 with other genes.