Conversion of volatile fatty acids into polyhydroxyalkanoate by Ralstonia eutropha

Aims:  The aims of this study were to optimize condensed corn solubles (CCS) as a medium for growth of Ralstonia eutropha and to determine the effects of individual volatile fatty acids (VFAs) on polyhydroxyalkanoate (PHA) production .
Methods and Results:  A CCS medium of concentration 240 g l⁻¹ with a carbon : nitrogen ratio of 50 : 1 was developed as the optimal medium. Cultures were grown in 1-l aerated flasks at 250 rev min⁻¹ at 30°C for 120 h. Comparable growth rates were observed in CCS vs a defined medium. At 48 h, VFAs were fed individually at different levels. Optimal levels of all the acids were determined to maximize PHA production. An overall comparison of the VFAs indicated that butyric and propionic acids provided the best results.
Conclusion:  An optimized CCS medium supported growth of R. eutropha . Butyric and propionic acids were the most efficient carbon sources to maximize PHA production when added at the 5 g l⁻¹ level.
Significance and Impact of the Study:  The study shows that a byproduct of ethanol industry can be effectively used as a low cost medium for PHA production, thus partly reducing the cost of commercialization of biopolymers.     

Characterization of a dihydrolipoyl dehydrogenase having diaphorase activity of Clostridium kluyveri

The Clostridium kluyveri bfmBC gene encoding a putative dihydrolipoyl dehydrogenase (DLD; EC 1.8.1.4) was expressed in Escherichia coli, and the recombinant enzyme rBfmBC was characterized. UV-visible absorption spectrum and thin layer chromatography analysis of rBfmBC indicated that the enzyme contained a noncovalently but tightly attached FAD molecule. rBfmBC catalyzed the oxidation of dihydrolipoamide (DLA) with NAD(+) as a specific electron acceptor, and the apparent K(m) values for DLA and NAD(+) were 0.3 and 0.5 mM respectively. In the reverse reaction, the apparent K(m) values for lipoamide and NADH were 0.42 and 0.038 mM respectively. Like other DLDs, this enzyme showed NADH dehydrogenase (diaphorase) activity with some synthetic dyes, such as 2,6-dichlorophenolindophenol and nitro blue tetrazolium. rBfmBC was optimally active at 40 degrees C at pH 7.0, and the enzyme maintained some activity after a 30-min incubation at 60 degrees C.     

Comparison of five tandem repeat loci between humans and chimpanzees.

Five tandem repeat loci were studied in humans and chimpanzees using VNTR probes derived from human DNA. Shared alleles were found at three loci and were often the modal allele in one species but never in both. There was no difference in the mean number of alleles per locus. However, these species exhibited substantially different levels of gene diversity, with chimpanzees monomorphic at two loci. Evidence of reduced variability in chimpanzees corroborates earlier comparisons using isozymes and plasma proteins. Molecular mechanisms, population dynamics, or both may be responsible for these differences. Equal numbers of alleles per locus may reflect high mutation rates. By one test, chimpanzees were out of equilibrium at one locus, which may reflect a typing error or population substructure. The long divergence time, and the high probability of backward mutations, precludes accurate estimation of genetic distance between these species.     

A novel transition state analog inhibitor of guanase based on azepinomycin ring structure: Synthesis and biochemical assessment of enzyme inhibition

Synthesis and biochemical inhibition studies of a novel transition state analog inhibitor of guanase bearing the ring structure of azepinomycin have been reported. The compound was synthesized in five-steps from a known compound and biochemically screened against the rabbit liver guanase. The compound exhibited competitive inhibition profile with a K_i of 16.7 ± 0.5 μM.     

A ‘Problematic fossil’ revealed:Pycnoporidium ? eomesozoicum Flügel, 1972 (Late Triassic,Tethys)—not an enigmatic alga but a strophomenid brachiopod (Gosaukammerella n.g.)

Summary The microproblematicumPycnoporidium ? eomesozoicum Flügel, 1972, from Upper Triassic reefs of the Alpine-Mediterranean region, Turkey Oman and Iran (originally interpreted as possible alga) represents the type species of a new strophomenid brachiopod genus (Gosaukammerella n.g.). The genus is characterized by a very small, millimeter-sized plano-convex shell, whose ventral valve is attached to the substratum (mainly sponges) by symmetrically arranged outgrowths developing from a pseudopunctate, lamellose foliated shell wall and composed of densely spaced subparallel ‘tubes’ comparable with productide spines secreted by papillose extensions of the mantle.Gosaukammerella seems to be the only reliable candidate for the existence of post-Paleozoic strophomenid (productid ?) brachiopods. Gosaukammerella eomesozoica is restricted to possibly cryptic, shaded reef environments inhabited predominantly by sponges serving as substrates for micromorphic brachiopods.     

Molecular and biochemical characterization of mungbean yellow mosaic India virus resistance in leguminous host <Emphasis Type="Italic">Vigna mungo</Emphasis>

Mungbean yellow mosaic India virus (MYMIV)—the causal agent of the yellow mosaic disease is responsible for severe damage of crops that are of great economic importance. In the current study, we explored the process of MYMIV infection and its natural resistance by analysing the expression of early and late viral genes at different time points in the leaves of resistant and susceptible Vigna mungo plants. Accordingly, we have periodically evaluated several biochemical parameters commonly associated with oxidative status of resistant and susceptible V. mungo plants during MYMIV infection. Our study revealed that accumulation levels of the early as well as late expressed genes of MYMIV were low and high in the resistant and susceptible plants, respectively; whereas membrane stability index (MSI) exhibited an opposite response. Moreover, a decrease in the malondialdehyde levels along with an increase in the activities/levels of different antioxidant enzymes, total phenol and H₂O₂ was noted during the early stages of infection in the resistant plants. Such observations argue in favour of strong defensive capability of the resistant plants in restricting the accumulation of viral RNA and generation of harmful free radicals within the studied tissue. Collectively, it appears that obstruction of viral invasion in plant cell wall, restriction in viral DNA replication, and early onset of antioxidant defense responses altogether might be responsible for MYMIV natural resistance. Such information is helpful in understanding the pathogenesis of MYMIV infection and its resistance in V. mungo and other economically important crops.     

Spatiotemporal cytokinin response imaging and ISOPENTENYLTRANSFERASE 3 function in Medicago nodule development

Most legumes can establish a symbiotic association with soil rhizobia that trigger the development of root nodules. These nodules host the rhizobia and allow them to fix nitrogen efficiently. The perception of bacterial lipo-chitooligosaccharides (LCOs) in the epidermis initiates a signaling cascade that allows rhizobial intracellular infection in the root and de-differentiation and activation of cell division that gives rise to the nodule. Thus, nodule organogenesis and rhizobial infection need to be coupled in space and time for successful nodulation. The plant hormone cytokinin (CK) contributes to the coordination of this process, acting as an essential positive regulator of nodule organogenesis. However, the temporal regulation of tissue-specific CK signaling and biosynthesis in response to LCOs or Sinorhizobium meliloti inoculation in Medicago truncatula remains poorly understood. In this study, using a fluorescence-based CK sensor (pTCSn::nls:tGFP), we performed a high-resolution tissue-specific temporal characterization of the sequential activation of CK response during root infection and nodule development in M. truncatula after inoculation with S. meliloti. Loss-of-function mutants of the CK-biosynthetic gene ISOPENTENYLTRANSFERASE 3 (IPT3) showed impairment of nodulation, suggesting that IPT3 is required for nodule development in M. truncatula. Simultaneous live imaging of pIPT3::nls:tdTOMATO and the CK sensor showed that IPT3 induction in the pericycle at the base of nodule primordium contributes to CK biosynthesis, which in turn promotes expression of positive regulators of nodule organogenesis in M. truncatula.

Precise spatial and temporal characterization of cytokinin (CK) responses reveals the function of the CK biosynthesis gene ISOPENTENYLTRANSFERASE 3 during nodule development in Medicago truncatula.     

Extracellular matrix proteome of chickpea (Cicer arietinum L.) illustrates pathway abundance, novel protein functions and evolutionary perspect

The extracellular matrix (ECM) or cell wall is a dynamic system and serves as the first line mediator in cell signaling to perceive and transmit extra- and intercellular signals in many pathways. Although ECM is a conserved compartment ubiquitously present throughout evolution, a compositional variation does exist among different organisms. ECM proteins account for 10% of the ECM mass, however, comprise several hundreds of different molecules with diverse functions. To understand the function of ECM proteins, we have developed the cell wall proteome of a crop legume, chickpea (Cicer arietinum). This comprehensive overview of the proteome would provide a basis for future comparative proteomic efforts for this important crop. Proteomic analyses revealed new ECM proteins of unknown functions vis-à-vis the presence of many known cell wall proteins. In addition, we report here evidence for the presence of unexpected proteins with known biochemical activities, which have never been associated with ECM.     

Expression of estrogen receptor {alpha} in the anteroventral periventricular nucleus of hypogonadal mice

Gonadotropin-releasing hormone-1 (GnRH-1) neurons play critical roles in the development and maintenance of reproductive function in all vertebrates. Due to a truncation in the GnRH-1 gene, hypogonadal (hpg) mice are unable to synthesize GnRH-1 and are infertile. These animals develop in the complete absence of exposure to gonadal steroid hormones, making them an interesting model for understanding brain sexual differentiation and dimorphism. We studied expression of the estrogen receptors (ERs) alpha and beta in the medial anteroventral periventricular nucleus (mAVPV), an important reproductive neuroendocrine brain region, in wild-type and hpg mice of both sexes. Adult wild-type and hpg mice of the same genetic background were used to quantify numbers of ERalpha and ERbeta immunoreactive cells in the mAVPV using a stereologic approach. Quantitative analyses showed that ERalpha cell numbers were significantly higher in hpg than wild-type mice, irrespective of sex. Qualitatively, ERalpha-immunoreactive cells were concentrated more densely along the ventricular zone of the AVPV of wild-type female mice compared with wild-type male mice or hpg male and female mice. No ERbeta-immunoreactive cells were detected in the mAVPV of any mice, a result that was surprising because ERbeta expression is abundant in the mAVPV of rats. These results on ERalpha provide additional evidence that the female brain is not the "default" organizational pattern, because neither ERalpha cell number nor its distribution in hpg mice, which develops with a deficiency of reproductive hormones, resembles that of the wild-type female mouse. Differences in ERalpha expression may be due in part to the absence of gonadal steroid hormones, although they more likely to also involve other factors, potentially GnRH itself.