Analysis of early growth of guppy strains,Poecilia reticulata,with different color patterns

Summary The guppy, Poecilia reticulata, is economically the most important species of freshwater ornamental fish cultured in Singapore. About 30 strains with different color patterns and fin shapes are reared in guppy farms practising monoculture in Singapore. To compare the growth rates of domesticated strains with different color patterns, newborn fry of 11 strains were obtained on the same day from a single farm in Singapore and were reared experimentally in the laboratory for about 100 days. Each strain was distributed randomly into 4 tanks with 30 fish/tank. Weekly weighings of 10 fish/tank were made from 17 to 100 days of age. Three strains were homozygous for the autosomal recessive blond gene which gives rise to a pale yellow background pigmentation (bb). These blond strains had significantly smaller body weights than corresponding ones with the same color pattern but with the wild-type grey-brown background coloration due to the dominant allele (BB). The strains with the red tail pattern due to a dominant X-linked gene (Rdt) had more rapid growth than those with other tail color patterns including the blue, black, green snakeskin and variegated. However, no significant differences were detected among the other color pattern strains. Thus among the strains studied, the blond strains were associated with slower growth while those with the red tail color were associated with faster growth.     

Electron microscopic visualization of asymmetric precursor translocation intermediates: SecA functions as a dimer

SecA, the ATPase of Sec translocase, mediates the post-translational translocation of preprotein through the protein-conducting channel SecYEG in the bacterial inner membrane. Here we report the structures of Escherichia coli Sec intermediates during preprotein translocation as visualized by electron microscopy to probe the oligomeric states of SecA during this process. We found that the translocase holoenzyme is symmetrically assembled by SecA and SecYEG on proteoliposomes, whereas the translocation intermediate 31 (I₃₁) becomes asymmetric because of the presence of preprotein. Moreover, SecA is a dimer in these two translocation complexes. This work also shows surface topological changes in the components of translocation intermediates by immunogold labeling. The channel entry for preprotein translocation was found at the center of the I₃₁ structures. Our results indicate that the presence of preprotein introduces asymmetry into translocation intermediates, while SecA remains dimeric during the translocation process.     

In vitro inhibition of human influenza A virus replication by chloroquine

Inhibition of the human cytomegalovirus UL97 kinase by maribavir is thought to be responsible for the antiviral activity of this compound. Some mutations that confer resistance to maribavir map to UL97, however additional mutations that also confer resistance to the drug were mapped to UL27. These open reading frames share a low level of homology, yet the function of pUL27 remains unknown. A recombinant virus with a deletion in the UL27 open reading frame was reported previously to exhibit a slight replication deficit, but a more important function in vivo was hypothesized given its homology to the UL97 kinase. The potential for an important function in vivo was investigated by determining if these knockout viruses could replicate in human tissue implanted in SCID mice. None of the AD169 derived viruses replicated well in the implanted thymus/liver tissue, and is consistent with previous observations, although all of the viruses replicated to some degree in retinal tissue implants. Replication of the parent viruses was observed at 7 days post inoculation, whereas no replication was detected with any of the recombinant viruses with deletions in UL27. By day 14, replication was detected in two of the three knockout viruses and in all of the viruses by day 42. These data are consistent with minimal defects observed in cell culture, but are not consistent with an important role for UL27 in vivo. We conclude that UL27 is not required for viral replication in vivo.     

Molecular differentiation of two morphological variants of Gracilaria salicornia

Xia in 1986 combined Gracilaria salicornia, G. canaliculata (G. crassa), G. cacalia and G. minor into one species: G.salicornia. Two morphological variants of G. salicornia were collectedfrom different localities in Malaysia. Variant A collected from Morib,Selangor grew on the roots of Avicennia. The samples showed absenceof main axis; segmented constrictions throughout; cylindrical or slightlycompressed thalli. Variant B was collected from the mudflats of TanjungTuan, growing on rocks, coral or forming mats on the mud. Plants showedabsence of main axis; segments were not constricted throughout the plant(if present only slightly articulated at the upper part), branching wasdichotomous or irregular; cylindrical or slightly compressed thalli. Thetechnique of Random Amplified Polymorphic DNA analysis (RAPD) wasused to investigate molecular characteristics of the two variants. Out ofsixty Operon primers that were screened, four primers, OPA 1, OPA 10,OPA 11 and OPK 7 were able to give polymorphism. The fingerprintsgenerated were stable and reproducible on repeated analysis. The DNAfingerprints generated were visually analysed and clustering analysis wascarried out using GelCompar 4.0. The matrix of similarities was based onthe Dice coefficients (S_D) and the cluster analysis was carried outusing the unweighted pair group method using arithmetic averages(UPGMA). DNA analysis showed that two primers (OPA 01, CAGGCCCTTC and OPK 07, AGCGAGCAAG) were able to differentiate the two variants.     

Effect of crystalloid administration on oxygen extraction in endotoxemic pigs

We asked whethercrystalloid administration improves tissue oxygen extraction inendotoxicosis. Four groups of anesthetized pigs(n = 8/group) received either normalsaline infusion or no saline and either endotoxin or no endotoxin. Wemeasured whole body (WB) and gut oxygen delivery and consumption duringhemorrhage to determine the critical oxygen extraction ratio(ER_O2 crit). Just after onset of ischemia (critical oxygen delivery rate), gut was removed for determination of area fraction of interstitial edema and capillary hematocrit. Radiolabeled microspheres were used todetermine erythrocyte transit time for the gut. Endotoxin decreased WBER_O2 crit(0.82 ± 0.06 to 0.55 ± 0.08, P < 0.05) and gutER_O2 crit(0.77 ± 0.07 to 0.52 ± 0.06, P < 0.05). Unexpectedly, saline administration also decreased WBER_O2 crit (0.82 ± 0.06 to 0.62 ± 0.08, P < 0.05) and gutER_O2 crit (0.77 ± 0.07 to 0.67 ± 0.06, P < 0.05) in nonendotoxin pigs. Saline administration increased thearea fraction of interstitial space (P < 0.05) and resulted in arterial hemodilution(P < 0.05) but not capillaryhemodilution (P > 0.05). Salineincreased the relative dispersion of erythrocyte transit times from0.33 ± 0.08 to 0.72 ± 0.53 (P < 0.05). Thus saline administration impairs tissue oxygen extractionpossibly by increasing interstitial edema or increasing heterogeneityof microvascular erythrocyte transit times.

     

Monoclonal Antibodies against Specific p53 Hotspot Mutants as Potential Tools for Precision Medicine

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Microdetermination of phosphorylated intermediates of sodium-potassium adenosine triphosphatase

We have described a simple, rapid, reliable, and sensitive method for measuring the covalent phosphoenzyme intermediates that form in the reaction of ATP and sodium-potassium sensitive adenosine triphosphatase. Results are reproducible even when microgram amounts of microsomal protein are used. The method involves recovery of ³²P-labeled phosphoenzyme intermediates on a Millipore filter.     

The importance of ornithine as a precursor for proline in mammalian cells.

Ornithine aminotransferase catalyzes the reversible transamination of L-ornithine to delta1-pyrroline-5-carboxylate, the immediate precursor of proline. The direction and flux through this pathway in mammalian cells has not been established. Glutamate has generally been considered to be the most important precursor for proline biosynthesis, but recent studies in xiphoid cartilage indicate that a significant fraction of cellular proline is derived from ornithine. Using newly isolated mutant Chinese hamster ovary cells with defined defects in the proline biosynthetic pathways, we now have established that cells can grow at a maximal rate with ornithine as the sole source of proline. Furthermore, we have measured the rate of proline formation from ornithine (1.6 nmol/h/10(6) cells); Future studies with these mutant Chinese hamster ovary cells may offer insight into the regulatory mechanism which coordinates proline biosynthesis from ornithine and glutamate.     

Effect of four chlorophytes on larval survival, development and adult body size of the mosquito Aedes aegypti

The effect of four microalgal chlorophytes, Chlorella vulgaris,Scenedesmus quadricauda, Chlorococcum sp. and Ankistrodesmus convolutus, on the survival, larval development and adultbody size of the mosquito Aedes aegypti was investigated. The percentage mortality of larvae fed with C. vulgaris, Chlorococcum sp.or S. quadricauda after six days was 100%, 84% and 88%,respectively. Delayed pupation and body size reduction of the mosquitoesfed with C. vulgaris, Chlorococcum sp. and S. quadricaudawere observed. In contrast, larvae fed with A. convolutus werebigger than those fed with normal insectory feed. The study showed thatC. vulgaris, S. quadricauda and Chlorococcum sp. have potentialto be used as larvicidal agents.