Epitope analysis and molecular modeling reveal the topography of the C-terminal peptide of the beta-subunit of human chorionic gonadotropin.

Human chorionic gonadotropin (hCG) belongs to a family of heterodimeric glycoprotein hormones that share a common alpha-subunit and a hormone-specific beta-subunit. Among the gonadotropin beta-subunits, greater than 85% homology exists between lutropin (hLH)beta and hCGbeta in their first 114 amino acid residues. However, unlike hLHbeta, hCGbeta contains a 31-amino acid hydrophilic stretch at its carboxyl end (CTPbeta: C-terminal peptide). Although the crystal structure of deglycosylated hCG has been solved, the topography of CTPbeta remains unknown. In this study, we have attempted to define the topology of CTPbeta using mAb probes. We investigated three epitopes on hCGalpha, which are hidden in the hCGalphabeta dimer. However, these epitopes are not hidden in hLH, which has a similar subunit interface to that of hCG, but lacks CTPbeta. This suggested that these epitopes are not masked at the subunit interface of hLH or hCG. Hence, we hypothesized that, in the case of hCG, these epitopes are masked by the CTPbeta. Consistent with this view, several treatments of hCG that removed CTPbeta unmasked these epitopes and enhanced their reactivity with the corresponding mAbs. In order to localise the position of CTPbeta on the alpha-subunit, we used an epitope-mapping strategy [N. Venkatesh & G. S. Murthy (1997) J. Immunol. Methods 202, 173-182] based on differential susceptibility of epitopes to covalent modifications. This enabled us to predict the possible topography of CTPbeta. Further, we were also able to build a model of CTPbeta, completely independently of the epitope-mapping studies, using a homology-based modeling approach [S. Krishnaswamy, I. Lakshminarayanan & S. Bhattacharya (1995) Protein Sci. 4 (Suppl. 2), 86-97]. Results obtained from these two different approaches (epitope analysis and homology modeling) agree with each other and indicate that portions of CTPbeta are in contact with hCGalpha in the native hCG dimer.     

Molecular organization of great millet (Sorghum vulgare) DNA

Approximately 52% of the nuclear genome of great millet(Sorghum vulgare) consists of repetitive DNA which can be grouped into very fast, fast and slow components. The reiteration frequencies of the fast and slow reassociating components are {dy7000} and 92 respectively. Approximately 90% of the genome consists of repeated sequences interspersed amongst themselves and with single copy sequences. The interspersed repeat sequences are of three sizesviz. > 1·5 kilobase pairs, 0·5–1·0 kilobase pairs and 0·15–0·30 kilobase pairs while the size of the single copy sequences is 3·0 kilobase pairs. Hence the genome organization of great millet is essentially of a mixed type NCL communication No. 3527.     

Metabolic differentiation of homologous leg muscles of two aquatic birds at the level of enzymatic organization

The quantitative determination of succinic dehydrogenase (SDH), hexokinase (HK), phosphorylase, phosphofructokinase (PFK), glycerol-3-phosphate dehydrogenase (G-3-PDH) and lactate dehydrogenase (LDH) was carried out in the homologous leg muscles of two aquatic Birds. It appears that the leg muscle fibres of the coot, a surface swimmer are more oxidative in nature and appear to utilize glucose as source of energy. The leg muscles of the dabchick, a diving Bird, on the other hand, seem to depend on glycogen as source of energy. The relative activity levels of HK, phosphorylase and PFK support the accepted r?le of glycogen as primary substrate of carbohydrate catabolism in the leg muscles. The ratio of G-3-PDH/LDH in the leg muscles revealed that glycerol 3-phosphate cycle appears to be insufficient to account for the major part of NADH oxidation. However, the LDH activity is quite high in all the muscles. These results led us to believe that glycerol 3-phosphate cycle may function during rest, when the rate of glycolysis will be low.     

Characterization of affinity-purified juvenile hormone esterase from the plasma of the tobacco hornworm, Manduca sexta

Juvenile hormone (JH) esterase found primarily in the hemolymph and tissues of insects is a low abundance protein involved in the ester hydrolysis of insect juvenile hormones, JHs. The enzyme was purified from the larval plasma of wild-type Manduca sexta using an affinity column prepared by binding the ligand, 3-[(4'-mercapto)butylthio]-1,1,1-trifluoropropan-2-one (MBTFP), to epoxy-activated Sepharose. The purification was greater than 700-fold with a 72% recovery, and the purified enzyme appeared as a single protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoelectrophoresis, reverse phase high performance liquid chromatography, and amino acid sequence analysis. The molecular weight was 66,000. The plasma JH esterase in wild-type, black, and white strains of M. sexta was similar when analyzed by immunotitration, wide range (pH 3.5-9.0) isoelectric focusing, and inhibition with MBTFP and 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP). Inhibition studies revealed a sensitive and insensitive form (I50 = 10(-9) and 10(-6) M, respectively) in these three biotypes. Narrow range isoelectric focusing (pH 4.0-7.0) indicated the presence of two major isoelectric forms with pI values of 6.0 and 5.5, but their inhibition kinetics with OTFP and O,O-diisopropyl phosphorofluoridate were identical.     

The role of male accessory-gland substance on female reproduction with some observations of spermatogenesis in the stable fly

The bulbous tubular portion of the median ejaculatory duct functions as the accessory gland in the male stable fly, Stomoxys calcitrans. The gland started to enlarge after emergence when the fly was fed on sugar-water or blood. Implants of accessory glands from sugar-water or blood-fed males were effective in stimulating oviposition in virgin females. The injection into females of accessory-gland extracts from males fed blood prevented insemination; this extract was effective in concentration as low as 0.25 gland per female. Accessory-gland extracts from sugar-water fed males were only partially effective in preventing female insemination. However, the accessory-gland extracts of male stable flies had little effect on insemination when injected into three other species of female dipterans.Spermatogenesis was completed by the time of emergence, or shortly thereafter, a process independent of blood feeding. Three types of spermatids were identified, forming a continuum of spermiogenesis stages. Fat, fusiform spermatozoa elongated to become thin, elongate and mature spermatozoa.     

A five‐step risk management process for geriatric dental practice during SARS‐CoV‐2 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is an RNA virus that causes coronavirus infection (COVID‐19). COVID‐19 is a highly contagious disease transmitted through respiratory droplets, saliva and other contact routes. Within 10 months of its outbreak, SARS‐CoV‐2 has infected more than 23 million people around the world. Evidence suggests that older adults are the most vulnerable to infection and have an increased risk of mortality. Reduced immunity and underlying medical conditions make them risk‐prone and vulnerable to critical care. Older adults affected with the SARS‐CoV‐2 virus present with distinct clinical manifestations necessitating specific treatment needs and management protocols. While it is crucial to prevent the spread of novel coronavirus (2019‐nCoV), the role of oral healthcare workers in addressing the specific needs of ageing adult patients by adopting specific guidelines and appropriate infection control protocols is timely. This paper aims to develop specific guidelines and protocols for the dental management of geriatric patients during the COVID‐19 pandemic.     

Granulometric analysis of spots in DNA microarray images

As the topological properties of each spot in DNA microarray images may vary from one another, we employed granulometries to understand the shape-size content contributed due to a significant intensity value within a spot. Analysis was performed on the microarray image that consisted of 240 spots by using concepts from mathematical morphology. In order to find out indices for each spot and to further classify them, we adopted morphological multiscale openings, which provided microarrays at multiple scales. Successive opened microarrays were subtracted to identify the protrusions that were smaller than the size of structuring element. Spot-wise details, in terms of probability of these observed protrusions,were computed by placing a regularly spaced grid on microarray such that each spot was centered in each grid. Based on the probability of size distribution functions of these protrusions isolated at each level, we estimated the mean size and texture index for each spot. With these characteristics, we classified the spots in a microarray image into bright and dull categories through pattern spectrum and shape-size complexity measures. These segregated spots can be compared with those of hybridization levels.