PCR-based DNA markers linked to a gall midge resistance gene, Gm4t, has potential for marker-aided selection in rice

Rice DNAs from a gall midge resistant variety, 'Abhaya', a susceptible variety, 'Tulsi' and their F3 progeny were screened using 500 random primers in conjunction with bulked-segregant analysis in a polymerase chain reaction (PCR) with a view to detecting random amplified polymorphic DNAs (RAPDs) linked to the gene, Gm4t, which confers resistance to gall midge, a dipteran insect pest of rice. A total of 454 primers were able to produce a distinct amplification pattern, and 3695 bands/loci were amplified between the phenotypically different parents. Of these, 304 bands were polymorphic between the parents, with 19 being phenotypespecific. One of these primers, E20, amplified 2 bands, E20570 and E20583, which are tightly linked to resistance and susceptibility, respectively. These specific bands were cloned and sequenced, and a 94% sequence homology was found between the two fragments. Two specific 20-mer oligonucleotides were synthesized, based on the sequence information of E20583, for use in PCR amplification directly from genomic DNAs. These PCR primers were able to amplify phenotype-specific bands, a 583-bp fragment in susceptible F3 lines and a 570-bp fragment in resistant F3 lines that had been derived from a cross between the parents, indicating their potential and utility for marker-aided selection of the Gm4t gene in rice. Its use would facilitate the early and efficient selection of resistant genes in plant breeding programmes and even in those areas where the insect is not known to occur. These phenotype-specific bands are single-copy sequences and are being mapped to ascertain their chromosomal location in rice.

Detection of a highly heterozygous locus in recombinant inbred lines of rice and its possible involvement in heterosis

Forty-seven recombinant inbred (RI) lines derived from a cross between two indica rices, cv 'Phalguna' and the Assam land race ARC 6650, were subjected to restriction fragment length polymorphism (RFLP) analysis using cloned probes defining 150 single-copy loci uniformly dispersed on the 12 chromosomes of rice. Of the probes tested, 47 detected polymorphism between the parents. Heterozygosity was calculated for each line and for each of the polymorphic loci. Average heterozygosity per line was 9.6% but was excessive (>20%) in the 5 lines that seemed to have undergone outcrossing immediately prior to harvest. Average heterozygosity detected by each probe across the 47 RI lines was 9.7%. The majority of probes revealed the low level of heterozygosity (<8%) expected for F5-F6 lines in a species showing about 5% outbreeding. On the other hand, 7 probes exhibited heterozygosity in excess of 15%, while with a eighth probe (RG2 from chromosome 11) heterozygosity varied according to the restriction enzyme employed, ranging from 2% with SaII to 72% with EcoRV. The presence of 34 recombination sites in a segment of the genome as short as 24 kb indicates a strong selection for recombination between two neighbouring loci, one required as homozygous for the 'Phalguna' allele, and the other heterozygous. Since selection was principally for yield advantage over that of the high-yielding parent, 'Phalguna', one or both of these loci may be important for heterosis in this cross. The results also indicate that heterozygosity as measured by RFLP can depend on the particular restriction endonuclease employed.

DNA markers tightly linked to a gall midge resistance gene (Gm2) are potentially useful for marker-aided selection in rice breeding

We have developed a polymerase chain reaction (PCR)-based assay that could effectively reduce the time period required to screen and select for Gall Midgeresistant rice lines under field conditions. The primers for the assay were designed on the basis of sequence information of two phenotype specific random amplified polymorphic DNA fragments which were found to be tightly linked to Gall Midge biotype-1 resistance gene (Gm2). The two RAPD fragments, F81700 in the susceptible parent 'ARC6650' and F10600 in the resistant parent 'Phalguna', were identified after screening 5450 loci using 520 random primers on genomic DNAs of 'ARC6650' and 'Phalguna'. These primers, when used in a multiplexed PCR, amplified specifically a 1.7-kb and 0.6-kb fragment in the susceptible and resistant parents, respectively. When this assay was performed on genomic DNAs of 44 recombinant inbred lines derived from 'ARC6650' x 'Phalguna' and 5 lines derived from other crosses where one of the parents was 'Phalguna', 'ARC6650' or their derivatives, the primers amplified a 1.7-kb fragment in all of the susceptible lines or a 0.6-kb fragment in all of the resistant ones. These markers can be of potential use in the marker-aided selection of Gall Midge biotype-1 resistant phenotypes. As screening for resistance can now be conducted independent of the availability of insects, the breeding of resistant varieties can be hastened.

The effects of corticosteroid and reduced glutathione on the endothelial viability during culture in MK medium. A light microscopy study

The effect of addition of dexamethasone and reduced glutathione to MK medium, in a concentration of 10(-3) Molar and 0.92 g/l, respectively, was evaluated. The post preservation corneal endothelial viability was assessed using light microscopy. Our results showed that the addition of dexamethasone to MK medium increased the preservation time of dog cornea from 7 to 10 days and that reduced glutathione could further increase the storage period to 12 days. It can be concluded that the addition of reduced glutathione to MK medium is an excellent means for intermediate term corneal preservation.

RFLP and RAPD mapping of the rice gm2 gene that confers resistance to biotype 1 of gall midge (Orseolia oryzae)

Gm2 is dominant gene conferring resistance to biotype 1 of gall midge (Orseolia oryzae Wood-Mason), the major dipteran pest of rice. The gene was mapped by restriction fragment length polymorphism (RFLP) analysis of a set of 40 recombinant inbred lines derived from a cross between the resistant variety 'Phalguna' and the susceptible landrace 'ARC 6650'. The gene is located on chromosome 4 at a position 1.3 cM from marker RG329 and 3.4 cM from RG476. Since the low (28%) polymorphism of this indica x indica cross hindered full coverage of the genome with RFLP markers, the mapping was checked by random amplified polymorphic DNA (RAPD)/bulked segregant analysis. Through the use of 160 RAPD primers, the number of polymorphic markers was increased from 43 to 231. Two RAPD primers amplified loci that co-segregated with resistance/susceptibility. RFLP mapping of these loci showed that they are located 0.7 cM and 2.0 cM from RG476, confirming the location of Gm2 in this region of chromosome 4. Use of these DNA markers will accelerate breeding for gall midge resistance by permitting selection of the Gm2 gene independently of the availability of the insect.

Epidemiology of Pseudomonas aeruginosa infections in a neonatal intensive care unit

During the 19-month study period, 48 (2 per cent) of the 2177 neonates admitted to the neonatal intensive care unit (NICU) yielded Pseudomonas aeruginosa growths in blood cultures. All these neonates had clinical and haematological evidences of sepsis. Prominent clinical features included sclerema, violaceus necrotic patches, necrotizing enterocolitis (NEC), conjugated hyperbilirubinaemia, and DIC. Over all mortality was 23 per cent, distinctly higher in premature neonates with RDS. The mean gestational age and birth weights (+/- SD) of these neonates were 36.42 (+/- 2.73) weeks and 2173.34 (+/- 567.33) g, respectively. Approximately half of the total cases had low birth weight. Other adverse perinatal events before the development of sepsis included birth asphyxia (60 per cent), neonatal resuscitation (67 per cent), meconium aspiration syndrome (29 per cent), hyaline membrane disease (8 per cent), prolonged hospitalization (44 per cent), closed incubator care (17 per cent), prolonged intravenous fluids (42 per cent), repeated blood sampling (63 per cent), and umbilical catheterization (4 per cent). Analysis of the trend of Pseudomonas sepsis in our NICU revealed six definite outbreaks (more than two cases) interspersed with occasional (one or two) cases. Six study months, however, remained free of Pseudomonas sepsis. Index case was demonstrable on seven occasions. Bacteriological surveillance of the NICU after onset of initial case/cases revealed statistically significant colonization of resuscitation equipment, baby placement sites, and various cleansing solutions by the same bacterial species (P < 0.05). It is possible that Pseudomonas was introduced to our NICU from transfer admissions from other hospitals since on four occasions index case was the one transferred from outside.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrauterine growth predictors

The present study was conducted to construct standards for midarm circumference and midarm/head circumference ratio to identify neonates at risk for metabolic complications and to assess the anthropometric variable which could be used to substitute weight to identify low birth weight neonates. A study of 2925 consecutive live births showed significant correlation (p less than or equal to 0.001) between different anthropometric variables studied. Since midarm circumference (MAC), midarm circumference/head circumference ratio (MAC/HC) and ponderal index (PI) had the least correlation with gestation, these were used as independent markers for gestation. Among these three, MAC had the best correlation with birth weight (r = 0.808). A midarm circumference of less than or equal to 8.6 cm and less than or equal to 7.4 cm had the best sensitivity and specificity for identifying neonates with a birth weight of less than or equal to 2500 and less than or equal to 2000 g, respectively. All the anthropometric variable studied can rule out low birth weight with great accuracy (high negative predictive value greater than 90%).

Coagulase negative staphylococcal septicemia in newborns

The case records of 2177 newborn infants admitted in the Neonatal Intensive Care Unit (NICU) from January, 1989, through July, 1990, with positive blood cultures for coagulase-negative staphylococci (C-NS) were evaluated. Seventy four (3.4%) neonates yielded C-NS in blood cultures during the study period. Of these, 58 (2.7%) infants had clinical and hematological features compatible with the diagnosis of septicemia. Remaining 16 babies with positive cultures had no evidence of sepsis, and were designated as "C-NS bacteremia". The age at which positive cultures were obtained differed between the bacteremic and septicemic groups. In bacteremic group, the onset occurred between one to four days of age. In contrast, in septicemic group the range was 6-20 days, with a mean of 10.22 (+/- 3.53) days. More than two third of total cases of C-NS sepsis were premature and low birth weight (LBW). Prominent clinical features included lethargy, poor feeding and fever. Besides this apneic spells were seen predominantly in babies weighing less than 1500 g. Further, before the diagnosis of C-NS sepsis, more than half of neonates had received prolonged intravenous fluid therapy, a quarter had undergone umbilical catheterization and a further quarter needed a ventilator support. Overall mortality in C-NS sepsis was 17.24%, distinctly higher in neonates with RDS and those requiring mechanical ventilation (p less than 0.05). Only 1.34% C-NS isolates were resistant to all routinely used antibiotics and sensitivity was maximum with newer cephalosporins, ciproflox and amikacin.

Effect of head-up tilting on systolic time intervals in normal young volunteers

Systolic time intervals (STI) are sensitive indices of myocardial function. Passive tilting is a rapidly reversible and non-invasive method for inducing cardiovascular stress. The present work was conducted to study the effect of graded head-up tilt (HUT) on STI. 20 male medical students were subjected to 30 degrees, 60 degrees and 80 degrees HUT on a tilting table. ECG, phonocardiogram and carotid pulse were recorded simultaneously on Grass polygraph. Electromechanical systole (QS2), left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LEVT ratio, heart rate (HR) and corrected STI were determined immediately after and at 1, 2, 3, 4 and 5 min after each angle tilt. HUT produced a decrease in QS2 which was more pronounced at higher angle tilt. LVET decreased after 60 degrees and 80 degrees HUT. PEP and PEP/LVET ratio decreased after each angle tilt. These changes in STI can be explained on the basis of sympathetic stimulation-induced increase in the inotropic state of the heart.

Clinico-biochemical study of experimental complicated cataracts

Clinically observed complicated cataracts, generally do not have a definite causal factor. We studied the effects of E. coli toxin injected suprachoroidally, to simulate the effect of toxins released by extraocular organisms on the lens. 79.2% of eyes had a definable cataract at the end of the 6th week of observation. The biochemical changes portrayed an increased oxidative activity in the lens, evidenced by a fall in glutathione concentration, and the consequent tertiary reorientation of proteins to increase insoluble proteins, forming a cataract.

Acute granulomatous iritis following 5 fluorouracil therapy for failed trabeculectomy

We are reporting a case which developed idiosyncratic anterior granulomatous uveitis following a single dose of subconjunctival 5 Fluorouracil. This has not been previously reported anywhere in the world.

Restriction fragment length polymorphism analysis of polymerase chain reaction products amplified from mapped loci of rice (Oryza sativa L.) genomic DNA

Thirty mapped Indica rice genomic (RG) clones were partially sequenced from each end. From such sequence data, pairs of oligonucleotides were synthesized to act as primers for polymerase chain reaction (PCR) amplification of the corresponding loci in crude total DNA preparations. The PCR products from DNA of Indica varieties were of the sizes expected from the sizes of the corresponding RG clones. However, size polymorphisms were seen between PCR products from Indica and Japonica varieties, and among wildOryza species. Restriction fragment length polymorphism (RFLP) was observed between PCR products of Indica varieties simply by electrophoretic analysis of restricted products, without the need for Southern hybridization or radiolabelling. The RFLPs noted between varieties ARC6650 and Phalguna were inherited in recombinant inbred lines derived from a cross between them. The RFLPs were detectable in PCR products amplified from DNA extracted by a simple procedure from single seedlings or leaves, and revealed genetic heterogeneity in cultivated lines. An approach is described that is relevant to the acceleration of classical plant breeding through molecular techniques.

Congenital syphilitic hepatitis

Hepatitis is a known manifestation of congenital syphilis, however hepatitis developing during penicillin therapy is unknown. Ten patients of congenital syphilis were studied and serial liver enzymes were done before and after starting penicillin therapy. Eight of the ten patients developed hepatitis after initiating penicillin therapy. Whether hepatitis in these cases was secondary to toxic reaction to the products of treponemal lysis or an autoimmune reaction needs to be investigated.

Oxidative stress induced by a copper-thiosemicarbazone complex

Copper thiosemicarbazones cause considerable oxidative stress. This effect may be related to their cytotoxicity. In the present work, the chemical and cellular properties of a new ligand, pyridoxal thiosemicarbazone (H2T), and its copper(II) chelate (CuT) are assessed. CuT is toxic to cultured Ehrlich ascites tumor cells, producing nearly complete cell kill at drug/cell ratios of 2.5-4 nmol/10(5) cells in a monolayer culture over a 48-h treatment period. This concentration is at least 1 order of magnitude lower than those required for a similar degree of cytotoxicity by H2T or CuCl2. The following observations support the view that activated oxygen species are generated by interaction of CuT with Ehrlich cells: (1) Room-temperature electron spin resonance spectroscopy and atomic absorption measurements show rapid cellular uptake and CuT-thiol adduct formation. (2) Cellular thiol content is reduced. (3) High levels of DNA strand scission result from 1-h treatments of cells by concentrations of CuT that cause growth inhibition and toxicity. (4) The extent of strand scission can be increased by addition of superoxide dismutase and decreased by catalase or DMSO in the treatment medium. Catalase and DMSO do not inhibit the toxic effect of CuT. This suggests that DNA damage is not responsible for inhibition of cell proliferation by CuT.