Expressing Vitreoscilla hemoglobin in statically cultured Acetobacter xylinum with reduced O(2) tension maximizes bacterial cellulose pellicle production

Vitreoscilla hemoglobin (VHb) was constitutively expressed in Acetobacter xylinum to enhance bacterial cellulose (BC) production. A pronounced enhancement of BC production in static culture was observed. Reducing O(2) tension in gaseous phase of the culture by tightly sealing the culture tube could also enhance BC production by 70%. O(2) tension in gaseous phase reduced from 21 to 15% in the sealed and static culture of VHb-expressing A. xylinum after 7 days cultivation, while 7.36g/l of BC with yield of 0.44 were obtained. BC pellicle production by VHb-expressing A. xylinum was successfully scaled-up in a sealed 4l disposable zip lock plastic bag with BC yield of 0.38 and concentration of 6.73g/l.     

The impact of logging on the abundance, species richness and community composition of butterfly guilds in Borneo

Abstract:  The impact of logging on the relative abundance, species richness and community composition of four butterfly guilds (generalists, herb specialists, liana specialists and tree specialists) was assessed in differentially disturbed logging treatments located within the province of Central Kalimantan, Indonesian Borneo. Logging affected the overall butterfly composition by increasing the dominance of liana specialists at the expense of tree specialists and increasing the species richness of herb specialists and, to a lesser extent, generalists. There was no significant difference, however, in the species richness of liana specialists or tree specialists across logging treatments. The species composition of all guilds differed significantly among logging treatments with the greatest difference between unlogged forest and road sites with older and recently logged forest intermediate between these extremes. Our results indicate that logging has a disparate effect on abundance and species richness within each butterfly guild. We suggest that shifts in the dominance of butterfly guilds are due to large-scale logging-induced changes in vegetation, particularly in relation to liana abundance. The higher butterfly species richness in logged areas on the other hand is probably because of butterfly species associated with open areas entering the logged forest from roads or other large open areas.     

Kinetic analysis and comparison of uptake, distribution, and excretion of 48V-labeled compounds in rats

Setyawati, I. A., K. H. Thompson, V. G. Yuen, Y. Sun, M. Battell, D. M. Lyster, C. Vo, T. J. Ruth, S. Zeisler, J. H. McNeill, and C. Orvig. Kinetic analysis and comparison of uptake,distribution, and excretion of⁴⁸V-labeled compounds in rats.J. Appl. Physiol. 84(2): 569-575, 1998.Vanadium has been found to be orally active in lowering plasmaglucose levels; thus it provides a potential treatment for diabetesmellitus. Bis(maltolato)oxovanadium(IV) (BMOV) is a well-characterizedorganovanadium compound that has been shown in preliminarystudies to have a potentially useful absorption profile. Tissuedistributions of BMOV compared with those of vanadyl sulfate (VS) werestudied in Wistar rats by using⁴⁸V as a tracer. In this study,the compounds were administered in carrier-added forms by either oralgavage or intraperitoneal injection. Data analyzed by a compartmentalmodel, by using simulation, analysis, and modeling (i.e., SAAM II)software, showed a pattern of increased tissue uptake with use of⁴⁸V-BMOV compared with⁴⁸VS. The highest⁴⁸V concentrations at 24 h aftergavage were in bone, followed by kidney and liver. Most ingested⁴⁸V was eliminated unabsorbed byfecal excretion. On average, ⁴⁸Vconcentrations in bone, kidney, and liver 24 h after oraladministration of ⁴⁸V-BMOV weretwo to three times higher than those of⁴⁸VS, which is consistent with theincreased glucose-lowering potency of BMOV in acute glucose loweringcompared with VS.

     

Purinergic signaling in tanycytes and its contribution to nutritional sensing

Tanycytes are hypothalamic radial glial-like cells with an important role in the regulation of neuroendocrine axes and energy homeostasis. These cells have been implicated in glucose, amino acids, and fatty acid sensing in the hypothalamus of rodents, where they are strategically positioned. While their cell bodies contact the cerebrospinal fluid, their extensive processes contact neurons of the arcuate and ventromedial nuclei, protagonists in the regulation of food intake. A growing body of evidence has shown that purinergic signaling plays a relevant role in this homeostatic role of tanycytes, likely regulating the release of gliotransmitters that will modify the activity of satiety-controlling hypothalamic neurons. Connexin hemichannels have proven to be particularly relevant in these mechanisms since they are responsible for the release of ATP from tanycytes in response to nutritional signals. On the other hand, either ionotropic or metabotropic ATP receptors are involved in the generation of intracellular Ca²⁺ waves in response to hypothalamic nutrients, which can spread between glial cells and towards neighboring neurons. This review will summarize recent evidence that supports a nutrient sensor role for tanycytes, highlighting the participation of purinergic signaling in this process.     

Evaluating hydrogen bond interactions in enzymes containing Mn(III)-histidine complexation using manganese-imidazole complexes

It is often difficult to control hydrogen bond interactions in small molecule compounds that model metalloenzyme active sites. The imidazole-containing ligands 4,5-dicarboxyimidazole (H(3)DCBI) and 4,5-dicarboxy- N-methylimidazole (H(2)MeDCBI) allow examination of the effects of internal hydrogen bonding between carboxylate and imidazole nitrogen atoms. A new series of mononuclear manganese imidazole complexes have been prepared using these ligands: Mn(III)(salpn)(H(2)DCBI)(DMF) (1), Mn(III)(salpn)(HMeDCBI) (2), Mn(III)(dtsalpn)(HMeDCBI) (3), [Mn(IV)(dtsalpn)(HMeDCBI)]PF(6) (4), Mn(III)(salpn)(H(2)DCBI) (5), Mn(III)(dtsalpn)(H(2)DCBI) (6), and Mn(IV)(dtsalpn)(H(2)DCBI)PF(6) (8). Complexes 1, 2, 3, 5, and 6 have been prepared by direct reaction of salpn [salpn=(salicylideneaminato)-1,3-diaminopropane)] or dtsalpn [dtsalpn=(3,5-di- t-butylsalicylideneaminato)-1,3-diaminopropane)] and H(3)DCBI and H(2)MeDCBI with Mn(III) acetate, while complexes 4 and 8 were made by bulk electrolysis of complex 3 or 6 in dichloromethane. Complexes 1, 2, and 6 were characterized by X-ray diffraction. The impact of hydrogen bonding interactions of the complexes has been demonstrated by X-ray diffraction, cyclic voltammetry, and EPR spectroscopy. In all complexes the central metal ion is present in a six-coordinate geometry. Magnetic susceptibility measurements confirm the spin and oxidation states of the complexes. The cyclic voltammograms of 3 and 6 in dichloromethane reveal single, reversible redox waves with E(1/2)=600 mV and 690 mV, respectively. The X-band EPR spectrum of 4 shows a broad signal around g=4.4, and the corresponding complex 8 possesses a broad signal at slightly lower field ( g=5.5) than 4. These studies demonstrate that even small changes in the effective charge of the imidazole ligand can have a profound impact on the structure, spectroscopy, and magnetism of manganese(IV) complexes. We use these observations to present a model that may explain the origin of the g=4.1 signal in the S(2) state of photosystem II.     

Divergence of the Response Induced by Xenogenic Immunization in the Sepsis Survival of Rats

We have previously described that boosted natural xenoantibodies in rats cross-react to bacteria by targeting carbohydrate antigens. This type of immunization is associated with reduced survival after cecal ligation and puncture (CLP). In the present study, we investigated further this phenomenon by immunizing Lewis rats with three intraperitoneal injections, every other day, of hamster blood compared to saline-injected control animals. One day after the last injection, CLP was performed to produce a low-grade sepsis. Induction of xenoantibodies was associated with a reduction in animal survival after CLP relative to controls (45% vs. 90%, p<0.01). No bacterial blood load was observed after CLP in this model either with or without xenoantibody enhancement, indicating that the augmented mortality was not mediated by a direct effect of boosted xenoantibodies over blood bacteria. Nevertheless, the xenoimmunization produced a systemic inflammatory response in all rats. Additionally, a lack of weight gain at the time of CLP was present in animals that died after the procedure, which was not observed in surviving rats and controls. The cytokine profile at the time of CLP in animals that died after the procedure was characterized by an increase in the serum level of several cytokines, particularly adipokines. In contrast, the cytokine profile at CLP of xenoimmunized rats that survived the procedure was characterized by a reduction in the level of cytokines. In conclusion, this study failed to show a direct effect of boosted xenoantibodies over blood bacterial isolates as cause for the decreased survival after CLP. However, it evidenced that non-infectious systemic inflammation may lead to a pattern of augmented cytokines, particularly adipokines, which impairs survival after subsequent CLP. Therefore, the profile of cytokines existing before the infectious insult appears more crucial than that resulting from the condition for the outcome of sepsis.     

Aedes aegypti abundance and insecticide resistance profiles in the Applying Wolbachia to Eliminate Dengue trial

The Applying Wolbachia to Eliminate Dengue (AWED) trial was a parallel cluster randomised trial that demonstrated Wolbachia (wMel) introgression into Ae. aegypti populations reduced dengue incidence. In this predefined substudy, we compared between treatment arms, the relative abundance of Ae. aegypti and Ae. albopictus before, during and after wMel-introgression. Between March 2015 and March 2020, 60,084 BG trap collections yielded 478,254 Ae. aegypti and 17,623 Ae. albopictus. Between treatment arms there was no measurable difference in Ae. aegypti relative abundance before or after wMel-deployments, with a count ratio of 0.96 (95% CI 0.76, 1.21) and 1.00 (95% CI 0.85, 1.17) respectively. More Ae. aegypti were caught per trap per week in the wMel-intervention arm compared to the control arm during wMel deployments (count ratio 1.23 (95% CI 1.03, 1.46)). Between treatment arms there was no measurable difference in the Ae. albopictus population size before, during or after wMel-deployment (overall count ratio 1.10 (95% CI 0.89, 1.35)). We also compared insecticide resistance phenotypes of Ae. aegypti in the first and second years after wMel-deployments. Ae. aegypti field populations from wMel-treated and untreated arms were similarly resistant to malathion (0.8%), permethrin (1.25%) and cyfluthrin (0.15%) in year 1 and year 2 of the trial. In summary, we found no between-arm differences in the relative abundance of Ae. aegypti or Ae. albopictus prior to or after wMel introgression, and no between-arm difference in Ae. aegypti insecticide resistance phenotypes. These data suggest neither Aedes abundance, nor insecticide resistance, confounded the epidemiological outcomes of the AWED trial.     

Self-immobilized recombinant Acetobacter xylinum for biotransformation

Biofilms have been successfully applied for biotransformation for decades, especially in the area of bioremediation due to the feature of harsh reaction condition resistance. Acetobacter xylinum is known for its cellulose pellicle forming capability. Like biofilm, A. xylinum cells are immobilized by simultaneously produced cellulose nanofibers in the pellicle. A recombinant A. xylinum was constructed with the expectation that the cells could be self-immobilized and achieve a desired and stable biotransformation. d-Amino acid oxidase (DAAO) of Rhodosporidium toruloides was used as the model enzyme to be expressed in the recombinant A. xylinum. The constructed recombinant A. xylinum not only successfully produced DAAO activity but also self-immobilized by cellulose nanofibers in both the static and shaken culture. Although self-immobilized cells demonstrated a DAAO activity approximately 10% of the cell crude extract activity, it provided the benefits of improved thermal stability, operational stability, and easy retrieval for repeated use.     

Butterfly species and traits associated with selectively logged forest in Borneo

Logging can significantly change the structure of rainforest communities. To better understand how logging drives this change, butterflies and environmental variables were assessed within both unlogged and logged forest in Indonesian Borneo. In the whole dataset, we found local environmental variables and geographic distance combined captured 53.1% of the variation in butterfly community composition; 29.6% was associated with measured local environmental variables, 13.6% with geographic distance between sites, and 9.9% with covariation between geographic distance and environmental variables. The primary axis of variation in butterfly community composition represented a disturbance gradient from unlogged to logged forest. Subsequent axes represented gradients influenced by variables such as canopy cover and total tree density. There were significant associations between environmental variables and geographic range and larval host plant use of species. Specifically, butterflies using trees as larval host plants and those with distributions limited to Borneo were more likely to be present in unlogged forest. By contrast, species that tended to be more abundant in logged forest were those with widespread distributions and those using lianas and grasses as larval host plants. The results of this study highlight the importance of environmental variables and disturbance, e.g., selective logging, in structuring rainforest community diversity. Moreover, they confirm how species traits, such as larval food use and geographic distributions can determine patterns of species abundance following environmental change.