Influences of two coexisting endosymbionts,CI‐inducing Wolbachia and male‐killing Spiroplasma,on the performance of their host Laodelphax striatellus (Hemiptera: Delphacidae)

The small brown planthopper Laodelphax striatellus (Hemiptera: Delphacidae) is reported to have the endosymbiont Wolbachia, which shows a strong cytoplasmic incompatibility (CI) between infected males and uninfected females. In the 2000s, female‐biased L. striatellus populations were found in Taiwan, and this sex ratio distortion was the result of male‐killing induced by the infection of another endosymbiont, Spiroplasma. Spiroplasma infection is considered to negatively affect both L. striatellus and Wolbachia because the male‐killing halves the offspring of L. striatellus and hinders the spread of Wolbachia infection via CI. Spiroplasma could have traits that increase the fitness of infected L. striatellus and/or coexisting organisms because the coinfection rates of Wolbachia and Spiroplasma were rather high in some areas. In this study, we investigated the influences of the infection of these two endosymbionts on the development, reproduction, and insecticide resistance of L. striatellus in the laboratory. Our results show that the single‐infection state of Spiroplasma had a negative influence on the fertility of L. striatellus, while the double‐infection state had no significant influence. At late nymphal and adult stages, the abundance of Spiroplasma was lower in the double‐infection state than in the single‐infection state. In the double‐infection state, the reduction of Spiroplasma density may be caused by competition between the two endosymbionts, and the negative influence of Spiroplasma on the fertility of host may be relieved. The resistance of L. striatellus to four insecticides was compared among different infection states of endosymbionts, but Spiroplasma infection did not contribute to increase insecticide resistance. Because positive influences of Spiroplasma infection were not found in terms of the development, reproduction, and insecticide resistance of L. striatellus, other factors improving the fitness of Spiroplasma‐infected L. striatellus may be related to the high frequency of double infection in some L. striatellus populations.     

Enhanced polyhydroxybutyrate (PHB) production via the coexpressed phaCAB and vgb genes controlled by arabinose PBAD promoter in Escherichia coli

Aim: To develop an approach to enhance polyhydroxybutyrate (PHB) production via the coexpressed phaCAB and vgb genes controlled by arabinose P_BAD promoter in Escherichia coli. Method and Results: The polyhydroxyalkanoates (PHAs) synthesis operon, (phaCAB), from Ralstonia eutropha was overexpressed under the regulation of the arabinose P_BAD promoter in Escherichia coli, and the vgb gene encoding bacterial haemoglobin from Vitreoscilla stercoraria (VHb) was further cloned at downstream of phaCAB to form an artificial operon. The cell dry weight (CDW), PHB content and PHB concentration were enhanced around 1·23‐, 1·57‐, and 1·93‐fold in the engineered cell harbouring phaCAB–vgb (SY‐2) upon 1% arabinose induction compared with noninduction (0% arabinose). Furthermore, by using a recombinant strain harbouring P_BAD promoter‐vgb along with native promoter‐phaCAB construction, the effect of vgb expression level on PHB biosynthesis was positive correlation. Conclusions: The results exploit the possibility to improve the PHB production by fusing the genes phaCAB–vgb from different species under the arabinose regulation system in E. coli. It also demonstrates that increase in VHb level enhances the PHB production. Significance and Impact of the Study: We were successful in providing a new coexpressed system for PHB synthesis in E. coli. This coexpressed system could be regulated by arabinose inducer, and is more stable and cheaper than other induced systems (e.g. IPTG). Furthermore, it could be applied in many biotechnology or fermentation processes.     

Biochemical Characterization of the Coating Mechanism of the Endosomal Donor Compartment of Synaptic Vesicles

The heterotetrameric adaptor protein complex, AP-3, sorts proteins to both the endosome/lysosome and the synaptic vesicles. We have characterized the recruitment of pure AP-3 complex and ADP-ribosylation factor (ARF) onto the endosomal donor compartments that give rise to synaptic vesicles. We demonstrated that endosomes become heavier in a sucrose gradient after incubation with rat brain cytosol and a nonhydrolyzable GTP analog, GTPgammaS. This process requires a small GTPase, ARF-1. Furthermore, the endosomal coating is specific for AP-3 but not the AP-2 complex. This process requires only two soluble proteins AP-3 and ARF, with the recruitment of AP-3 being saturable at about 30 nM. These results establish that the synaptic vesicle's donor membrane is coated with AP-3 before vesiculation, in a coat-protein-specific and dose-dependent fashion.     

A probabilistic method to correlate ion pairs with protein thermostability

Recent developments in research on the stability of proteins - specifically, comparisons of the ion pairs of homologous structures - show that ion pairs potentially contribute to the thermostability of proteins. This study proposes a probabilistic Bayesian statistical method to efficiently predict the thermostability of proteins based on the properties of ion pairs. The experimental results suggest that the numbers, types and bond lengths of ion pairs can be used to predict with high accuracy (up to 80%) the thermostability of functionally similar proteins. The predictions have high precision (99%), especially for hyperthermophilic proteins. Results for proteins with differing functions also indicate that the number of ion pairs is related to the thermostability of proteins, and that predictions of thermostability can also be made for proteins with different functions.     

A systematic review of the literature examining the diagnostic efficacy of measurement of fractionated plasma free metanephrines in the biochemical diagnosis of pheochromocytoma

BACKGROUND: Fractionated plasma metanephrine measurements are commonly used in biochemical testing in search of pheochromocytoma. METHODS: We aimed to critically appraise the diagnostic efficacy of fractionated plasma free metanephrine measurements in detecting pheochromocytoma. Nine electronic databases, meeting abstracts, and the Science Citation Index were searched and supplemented with previously unpublished data. Methodologic and reporting quality was independently assessed by two endocrinologists using a checklist developed by the Standards for Reporting of Diagnostic Studies Accuracy Group and data were independently abstracted. RESULTS: Limitations in methodologic quality were noted in all studies. In all subjects (including those with genetic predisposition): the sensitivities for detection of pheochromocytoma were 96%-100% (95% CI ranged from 82% to 100%), whereas the specificities were 85%-100% (95% CI ranged from 78% to 100%). Statistical heterogeneity was noted upon pooling positive likelihood ratios when those with predisposition to disease were included (p < 0.001). However, upon pooling the positive or negative likelihood ratios for patients with sporadic pheochromocytoma (n = 191) or those at risk for sporadic pheochromocytoma (n = 718), no statistical heterogeneity was noted (p = 0.4). For sporadic subjects, the pooled positive likelihood ratio was 5.77 (95% CI = 4.90, 6.81) and the pooled negative likelihood ratio was 0.02 (95% CI = 0.01, 0.07). CONCLUSION: Negative plasma fractionated free metanephrine measurements are effective in ruling out pheochromocytoma. However, a positive test result only moderately increases suspicion of disease, particularly when screening for sporadic pheochromocytoma.     

A protein dissection study demonstrates that two specific hydrophobic clusters play a key role in stabilizing the core structure of the molten globule state of human alpha-lactalbumin

The molten globule state of alpha-lactalbumin (alpha LA) has served as a paradigm for understanding the role of these partially folded states in protein folding. We previously showed that a peptide construct consisting of the A and B helices (residues 1-38) cross-linked to the D- and C-terminal 3(10) helices (residues 101-120) of alpha LA is capable of folding to a stable molten globule-like state. Here, we report the study of three peptide constructs that are designed to investigate the contribution two short hydrophobic sequences located near the C-terminus of alpha LA make to the structure and stability of the alpha LA molten globule state. These regions of the protein have been shown to form stable non-native structures in isolation. The three peptide constructs contain residues 1-38 cross-linked to three separate C-terminal peptides via the native 28-111 disulfide bond. The C-terminal peptides consist of residues 101-114, 106-120, and 106-114. The results of CD, fluorescence, ANS binding, and urea denaturation experiments indicate that constructs that lack either of the hydrophobic sequences (residues 101-105 and 115-120) are significantly less structured. These results highlight the importance of long-range, mutually stabilizing interactions within the molten globule state of the protein. Proteins 2001;42:237-242.     

Determination of urinary beryllium,arsenic, and selenium in steel production workers

Some of the most pernicious dangers of pollution arise from the presence of traces of toxic elements in the environment. In this work, we report on the determination of beryllium, arsenic, and selenium in the urine of steel production and steel quality control (QC) workers, in comparison to healthy control subjects. The urine samples were digested by a microwave system. Graphite furnace and hydride atomic absorption was used for the quantitative measurements of Be and As and Se, respectively. A quality control method for these procedures was established with concurrent analysis of Standard Trace Metals 7879 Level II and NIST SRM 2670 (Toxic Elements in Freeze Dried Urine). The results show that the urinary levels of these elements in steel production (As, 38.1±28.7 μg/L; Be, 1.58±0.46 μg/L, and Se, 69.2±28.8μg/L) and in quality control workers (As, 23.9±18.1 μg/L; Be, 1.58±0.46 μg/L, and Se, 54.8±25.1 μg/L) are significantly higher than in the controls (As, 10.3±8.7 μg/L; Be, 0.83±0.46 μg/L; and Se, 32.3±13.5 μg/L). The possible connection of these elements with the etiology of disease and the possible role of selenium as a protective agent against the oncogenic and teratogenic action of other substances is discussed. We suggest the need for improvement of environmental conditions in the workplace through better ventilation and industrial hygiene practices.