Backbone 1H, 13C and 15N resonance assignments of an intrinsically unstructured βγ-crystallin from Hahella chejuensis

The sequence specific backbone ¹H, ¹³C and ¹⁵N resonance assignments of an intrinsically unstructured βγ-crystallin from Hahella chejuensis are reported. The secondary structure chracterization of the unstructured protein reveals that large fraction of residues exhibits β-strand propensity, as in the case of the Ca²⁺-bound structured protein.     

Preliminary Studies on the Association Between Zooplankton and the Stramenopilan Fungi, Aplanochytrids

The relationship of the marine heterokont stramenopilan protists, the aplanochytrids, with the zooplankton was studied in coastal waters. The aplanochytrids were fed to the zooplankton specimens and observed for grazing by two different approaches: [1] using fluorescently-labeled prey approach and [2] using internal transcribed spacer-based molecular probe and in situ hybridization approach. The aplanochytrid cells were detected in the guts as well as fecal pellets of the zooplankton, thus serving as prey to them. Aplanochytrids were consistently isolated from zooplankton specimens. The isolates did not produce a wide array of enzymes, implicating that they may not play a major role in degradation of zooplankton exoskeleton. They were found to produce only protease considerably and sometimes lipase too. The amplified rDNA restriction analysis showed similar patterns, suggesting that most of the isolates might be same strains of Aplanochytrium spp. The existence of aplanochytrids with the zooplankton in marine waters points towards their probable association either as predator–prey or as commensalistic rather than saprophytic type of association.     

Studies on organic removal of 2,4-dichlorophenol wastewaters using a modified RBC

Phenolic compound wastes from a large number of industries big and small which are highly toxic and pose a direct threat to human and aquatic life are generally let into the rivers and coastal waters. 2,4-dichlorophenol is used in the manufacture of industrial and agricultural products such as pesticides, germicides, soil sterilants, seed disinfectants and antiseptics. A modified Rotating Biological Contactor (RBC) was used for the treatability studies of synthetic 2,4-di-chlorophenolic (2,4 CP) wastewaters. The RBC used was a four stage laboratory model and the discs were modified by attaching porous netlon sheets to enhance biofilm area and volume. Synthetic wastewaters were prepared with influent concentrations from 40 to 200?mg/l of 2,4 CP. Four hydraulic loads were used in the range of 0.024 to 0.065 m³.m^-2.d^-1 and the organic loads used were in the range of 2 to 13?g 2,4 CP.m^-2.d^-1. The RBC was operated at a speed of 12?rpm. Effect of hydraulic loadings and influent 2,4-dichlorophenol concentration on 2,4-dichlorophenol removal were discussed and showed maximum organic removal at hydraulic loads of 0.024 and 0.046?m³.m^-2.d^-1. Also, a correlation plot between 2,4 CP applied and 2,4 CP removed was presented. A mathematical model was proposed using regression analysis.     

Residual FDG‐PET metabolic activity in metastatic melanoma patients with prolonged response to anti‐PD‐1 therapy

18‐Fluorodeoxyglucose positron emission tomography (FDG‐PET) scans were performed on 27 patients with unresectable stage IIIC or IV melanoma after prolonged treatment with anti‐PD‐1 antibodies to examine the hypothesis that patients with prolonged response to treatment may have metabolically inactive lesions by FDG‐PET. Scans were performed at a median of 15.2 months (range 12–29 months) after starting treatment. Overall, 15 of 27 (56%) patients had a positive FDG‐PET scan. Eight patients with positive scans underwent biopsy; 5 of 8 (62%) were melanoma and 3 of 8 (38%) were immune cell infiltrates. Of the 12 patients with negative FDG‐PET scans, six had residual computerized tomography‐visible lesions, five have ceased treatment, and none have recurred with follow‐up of 6–10 months. Patients with residual metastases after a prolonged period without progression on anti‐PD‐1 therapy may have metabolically inactive lesions. Isolated metabolically active lesions in clinically well patients may reveal immune cell infiltrates rather than melanoma.     

Three-Directional Evaluation of Mitral Flow in the Rat Heart by Phase-Contrast Cardiovascular Magnetic Resonance

Purpose

Determination of mitral flow is an important aspect in assessment of cardiac function. Traditionally, mitral flow is measured by Doppler echocardiography which suffers from several challenges, particularly related to the direction and the spatial inhomogeneity of flow. These challenges are especially prominent in rodents. The purpose of this study was to establish a cardiovascular magnetic resonance (CMR) protocol for evaluation of three-directional mitral flow in a rodent model of cardiac disease.

Materials and Methods

Three-directional mitral flow were evaluated by phase contrast CMR (PC-CMR) in rats with aortic banding (AB) (N = 7) and sham-operated controls (N = 7). Peak mitral flow and deceleration rate from PC-CMR was compared to conventional Doppler echocardiography. The accuracy of PC-CMR was investigated by comparison of spatiotemporally integrated mitral flow with left ventricular stroke volume assessed by cine CMR.

Results

PC-CMR portrayed the spatial distribution of mitral flow and flow direction in the atrioventricular plane throughout diastole. Both PC-CMR and echocardiography demonstrated increased peak mitral flow velocity and higher deceleration rate in AB compared to sham. Comparison with cine CMR revealed that PC-CMR measured mitral flow with excellent accuracy. Echocardiography presented significantly lower values of flow compared to PC-CMR.

Conclusions

For the first time, we show that PC-CMR offers accurate evaluation of three-directional mitral blood flow in rodents. The method successfully detects alterations in the mitral flow pattern in response to cardiac disease and provides novel insight into the characteristics of mitral flow.     

The first range-wide assessment of Saddle-billed Stork Ephippiorhynchus senegalensis distribution

The Saddle-billed Stork Ephippiorhynchus senegalensis exemplifies a case in conservation research in which a species is assessed as Least Concern on the IUCN Red List and the resulting consideration of low conservation priority has precluded proper scientific study. As a first step in understanding this stork’s true status, we collated all available data to develop a distribution map and then investigated range-wide patterns of occurrence. The updated map greatly improves on past knowledge of the stork’s distribution and helps to identify regions where range contractions have occurred, particularly in Central Africa and parts of West Africa. We found that the stork’s distribution closely overlaps with protected areas and that there has been an overall increase in surface water (largely manmade water bodies)—a proxy for habitat—across the species’ extent of occurrence in recent decades. While this research represents a valuable contribution to our understanding of the Saddle-billed Stork, it also highlights the need for unbiased empirical data, especially from areas that are poorly surveyed, for developing a science-based conservation status assessment.     

Evolution of the mouse beta-globin genes: a recent gene conversion in the Hbbs haplotype

We have determined the complete nucleotide sequence of the two nonallelic adult beta-globin genes of the C57BL/10 mouse. These genes, designated beta s and beta t, show a sequence similarity of 99.6% over the region bordered by the translational start and stop codons. Both beta s and beta t encode functional polypeptide chains that are identical. A comparison of the C57BL/10 beta-globin haplotype, Hbbs, with that of the BALB/c mouse, Hbbd, suggests that the two haplotypes have distinct evolutionary histories. The two adult beta-globin genes of the Hbbd haplotype, beta dmaj and beta dmin, are 16% divergent at the nucleotide level and encode distinct polypeptides that are synthesized in differing amounts. Our analysis indicates that a gene correction mechanism has been operating on the Hbbs chromosome to keep beta s and beta t evolving in concert, whereas on the Hbbd chromosome, beta dmin has diverged considerably from beta dmaj. We suggest that gene conversion is responsible for the maintained similarity of the Hbbs genes. Furthermore, we attribute the divergence of the Hbbd genes in part to the absence of a region of simple-sequence DNA within the large intervening sequence of beta dmin. We propose that this region of DNA plays a role in facilitating gene conversion. The deletion of this area in beta dmin introduced a block of nonhomology between the beta dmaj-beta dmin gene pair and thus may have inhibited further gene correction within the Hbbd haplotype.      

Chromosome aberrations in lymphocytes of mice after sub-acute low-level inhalation exposure to benzene

Male and female CD-1 mice were exposed to near ambient air concentrations of benzene by inhalation for 22 h per day, 7 days per week for 6 weeks. The concentrations were 0, 40, 100 and 1000 ppb. Significant increases in chromosome aberrations in spleen lymphocytes were observed in exposed compared with control mice except in the high-dose group (p less than 0.05 for female mice in 2 experiments and for male mice in 1 experiment; p less than 0.15 for male mice in the second experiment). A lack of increase in aberrations among mice of the high-dose group may be due to an induction of detoxifying enzymes as observed by us in a previous study (Au et al., 1988b). We also found that the female mice were more sensitive to the clastogenic activity of benzene than male mice under our experimental conditions. Our study serves to emphasize the need to conduct subchronic, low-dose in vivo genotoxicity studies using exposure conditions similar to those of humans, for evaluation of potential hazards. Our data suggest that the current occupational exposure concentrations for benzene (less than 1000 ppb) may still be hazardous to humans.     

Functional expression of intrinsic factor-cobalamin receptor by renal proximal tubular epithelial cells.

Previous studies from our laboratory (Seetharam, B., Levine, J. S., Ramasamy, M., and Alpers, D. H. (1988) J. Biol. Chem. 263, 4443-4449; Fyfe, J. C., Ramanujam, K. S., Ramaswamy, K., Patterson, D. F., and Seetharam, B. (1991) J. Biol. Chem. 266, 4489-4494) have identified and isolated a 230-kDa receptor from rat and canine kidney which binds with high affinity [57Co]cyanocobalamin (Cbl) complexed to gastric intrinsic factor (IF). Although these studies have identified a renal receptor which binds intrinsic factor-cobalamin (IFCR), it is not known whether the binding is specific for IF-Cbl and whether renal cells internalize [57Co]Cbl bound to IF and transport [57Co]Cbl across the cell. Using a variety of renal cells, our results show that IF-[57Co]Cbl binding activity is detected in proximal tubular-derived epithelial cells from opossum (OK) and porcine kidney (LLC-PK1) but not in distal tubular-derived cells from canine kidney cells (MDCK). Metabolic labeling studies with Tran 35S-label confirmed the presence of a 230-kDa IFCR in OK and LLC-PK1 cells. Cell surface labeling and binding studies demonstrated that IFCR is targeted to the apical membrane. This apical expression of IFCR in OK cells is inhibited by the microtubule-disruptive drugs, colchicine and nocodazole. Opossum kidney cells when grown on culture inserts are polarized and transport [57Co]Cbl only when bound to IF and not to other Cbl binders. Furthermore, the transport of [57Co]Cbl occurred unidirectionally from the apical to the basolateral surface. Treatment of cells with colchicine or nocodazole inhibited the surface binding of IF-[57Co]Cbl as well as the transcytosis of [57Co]Cbl by 70-75%. IFCR retained intracellualarly by incubation of cells with colchicine or nocodazole is degraded by leupeptin-sensitive proteases. Based on these results, we suggest that proximal tubular-derived epithelial cells transport [57Co]Cbl bound to IF in a saturable way via receptor-mediated endocytosis.     

Organic reduction of tapioca wastewaters using modified RBC

A modified Rotating Biological Contactor (RBC) was used for the treatability studies of synthetic tapioca wastewaters. The RBC used was a four stage laboratory model and the discs were modified by attaching porous nechlon sheets to enhance biofilm area. Synthetic tapioca wastewaters were prepared with influent concentrations from 927 to 3600 mg/l of COD. Three hydraulic loads were used in the range of 0.03 to 0.09 m³·m^–2·d^–1 and the organic loads used were in the range of 28 to 306 g COD· m^–2·d^–1. The percentage COD removal were in the range from 97.4 to 68. RBC was operated at a rotating speed of 18 rpm which was found to be the optimal rotating speed. Biokinetic coefficients based on Kornegay and Hudson models were obtained using linear analysis. Also, a mathematical model was proposed using regression analysis.List of Symbols A m² total surface area of discs - d m active depth of microbial film onany rotating disc - K _s mg ·l^–1 saturation constant - P mg·m^–2·^–1 area capacity - Q l·d^–1 hydraulic flow rate - q m³·m^–2·d^–1 hydraulic loading rate - S ₀ mg·l^–1 influent substrate concentration - S _e mg·l^–1 effluent substrate concentration - w rpm rotational speed - V m³ volume of the reactor - X _f mg·l^–1 active biomass per unit volume ofattached growth - X _s mg·l^–1 active biomass per unit volume ofsuspended growth - X mg·l^–1 active biomass per unit volume - Y _s yield coefficient for attachedgrowth - Y _A yield coefficient for suspendedgrowth - Y yield coefficient, mass of biomass/mass of substrate removed Greek Symbols hr mean hydraulic detention time - (_max)_A d^–1 maximum specific growth rate forattached growth - (_max)_s d^–1 maximum specific growth rate forsuspended growth - _max d^–1 maximum specific growth rate - d^–1 specific growth rate - _v mg·l^–1·hr^–1 maximum volumetric substrateutilization rate coefficient