Distribution of transfer RNA genes in thePisum sativum chloroplast DNA

Purified chloroplast tRNAs were isolated fromPisum sativum leaves and radioactively labeled at their 3′ end using tRNA nucleotidyl transferase and α³²P-labeled CTP. Pea ctDNA was fragmented using a number of restriction endonucleases and hybridized with thein vitro labeled chloroplast tRNAs by DNA transfer method. Genes for tRNAs have been found to be dispersed throughout the chloroplast genome. A closer analysis of the several hybrid regions using recombinant DNA plasmids have shown that tRNA genes are localized in the chloroplast genome in both single and multiple arrangements. Two dimensional gel electrophoresis of total ct tRNA have identified 36 spots. All of them have been found to hybridize withPisum sativum ctDNA. Using recombinant clones, 30 of the tRNA spots have been mapped inPisum sativum ctDNA.     

Genetic variations at the T cell receptor γ locus in circulating peripheral blood mononuclear cells of clinically categorised leprosy patients

The allelic polymorphisms at exon 3 and exon 2 of the T cell receptor (TCR) Cγ2 (TRGC2) gene, generating 18-kb and 5.4-kb HindIII fragments, respectively, were found to be more frequent in multibacillary leprosy patients than in the controls (P < 0.005 and P < 0.001, respectively) when screened with the IDP2.11 probe. The frequencies of heterozygotes for the 18-kb allele and homozygotes for the 5.4-kb allele were found to be significantly higher in the multibacillary patients than in the controls (P < 0.001). Interestingly, the 8.0-kb allele, originating from the triplication of exon 2 of Cγ2, was observed exclusively in the paucibacillary leprosy patients. Further, when DNA samples were screened with the pH60 probe for the HindIII RFLP at the TCR Jγ2 (TRGJ2) gene segment, the 2.1-kb allele was again more prevalent in leprosy patients with the multibacillary form of the disease than in the paucibacillary patients and the controls (P < 0.025). The frequency of homozygotes for the 2.1-kb allele was also significantly higher in the multibacillary patients than in the paucibacillary patients (P < 0.010) and the controls (P < 0.025). A significant difference was observed in the frequencies of detectable rearrangements involving the Vγ7/8 and Vγ9 gene segments at the γ locus between circulating peripheral blood mononuclear cells of the multibacillary leprosy patients and the controls. These rearrangements were detected less frequently in the multibacillary patients (P < 0.001 for Vγ7/8 and P < 0.005 for Vγ9). Received: 28 October 1996 / Accepted: 13 February 1997     

Three bridged 14β,26-epoxy-C-homo-pentacyclic triterpenes from Primula rosea

Three new bridged 14β,26-epoxy-C-homo-pentacyclic triterpenes isolated from Primula rosea have been shown to be 14β,26-epoxy-serratane-3,21-dione, 21α-hydroxy-14β,26-epoxy-serratane-3-one and 21β-hydroxy-14β,26-epoxy-serratane-3-one, respectively, on the basis of ¹H NMR, ¹³C NMR and mass spectral and chemical evidence.     

13a-hydroxytylophorine from tylophora hirsuta

13a-hydroxytylophorine isolated from Tylophora hirsuta on heating with concentrated hydrochloric acid gave a quaternized salt which was reduced with sodium borohydride to (+)-tylophorine. An amine and a ketoamine having a seco[10–13a] bond were formed after lithium aluminium hydride reduction and chromium trioxide oxidation, respectively.     

Olfactory perceptual decision-making is biased by motivational state

Growing evidence suggests that internal factors influence how we perceive the world. However, it remains unclear whether and how motivational states, such as hunger and satiety, regulate perceptual decision-making in the olfactory domain. Here, we developed a novel behavioral task involving mixtures of food and nonfood odors (i.e., cinnamon bun and cedar; pizza and pine) to assess olfactory perceptual decision-making in humans. Participants completed the task before and after eating a meal that matched one of the food odors, allowing us to compare perception of meal-matched and non-matched odors across fasted and sated states. We found that participants were less likely to perceive meal-matched, but not non-matched, odors as food dominant in the sated state. Moreover, functional magnetic resonance imaging (fMRI) data revealed neural changes that paralleled these behavioral effects. Namely, odor-evoked fMRI responses in olfactory/limbic brain regions were altered after the meal, such that neural patterns for meal-matched odor pairs were less discriminable and less food-like than their non-matched counterparts. Our findings demonstrate that olfactory perceptual decision-making is biased by motivational state in an odor-specific manner and highlight a potential brain mechanism underlying this adaptive behavior.

Growing evidence suggests that internal factors influence how we perceive the world; this study shows that food intake influences how humans perceive food odors, such as the scent of cinnamon buns. This effect is specific to meal-matched odors, and is paralleled by changes in odor-evoked brain activity.     

Effect of Age-Stiffening Tissues and Intraocular Pressure on Optic Nerve Damages

Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; and age-stiffening from 35 to 60 years old increased the potential vision loss to 52%. These results showed that while IOP plays a central role in glaucomatous damages, age-stiffening facilitates glaucomatous damages and may be the principal factor that resulted in a higher rate of glaucoma in the elderly than the general population.     

Discovery of biclonal origin and a novel oncogene SLC12A5 in colon cancer by single-cell sequencing

Single-cell sequencing is a powerful tool for delineating clonal relationship and identifying key driver genes for personalized cancer management. Here we performed single-cell sequencing analysis of a case of colon cancer. Population genetics analyses identified two independent clones in tumor cell population. The major tumor clone harbored APC and TP53 mutations as early oncogenic events, whereas the minor clone contained preponderant CDC27 and PABPC1 mutations. The absence of APC and TP53 mutations in the minor clone supports that these two clones were derived from two cellular origins. Examination of somatic mutation allele frequency spectra of additional 21 whole-tissue exome-sequenced cases revealed the heterogeneity of clonal origins in colon cancer. Next, we identified a mutated gene SLC12A5 that showed a high frequency of mutation at the single-cell level but exhibited low prevalence at the population level. Functional characterization of mutant SLC12A5 revealed its potential oncogenic effect in colon cancer. Our study provides the first exome-wide evidence at single-cell level supporting that colon cancer could be of a biclonal origin, and suggests that low-prevalence mutations in a cohort may also play important protumorigenic roles at the individual level.