Biomedical subjects

Kanjana Thumanu

Publications and source records attributed to Kanjana Thumanu.

3 recordsLinked to original sources

PubMed2026

Breed classification of Lao People's Democratic Republic (Lao PDR) and Thai native chickens using synchrotron radiation-based Fourier transform infrared spectroscopy and genotyping by sequencing.

Lao PDR harbors substantial genetic diversity in native chicken populations, representing an important resource for sustainable production and long-term food security. This study aimed to classify five Lao native chicken breeds-Ou, Black Bone, Horn Chou, Yolk, and Chae-and to discriminate them from a Thai native breed, Leung Hang Khao (LK), using integrative genotype-based approaches. Blood samples were collected from 50 LK and Lao native chickens (32 Ou, 10 Black Bone, 9 Horn Chou, 121 Yolk, and 41 Chae). Genomic DNA was extracted and analyzed using synchrotron radiation-based Fourier-transform infrared (SR-FTIR) spectroscopy to characterize biochemical composition, while genotyping-by-sequencing (GBS) was employed to identify genome-wide single nucleotide polymorphisms (SNPs). SR-FTIR analysis revealed highly significant differences among breeds in nucleotide-associated functional groups, including thymine, adenine, guanine, cytosine, as well as DNA backbone and deoxyribose components (P < 0.001). Multivariate analyses demonstrated that principal component analysis (PCA) of SR-FTIR spectra effectively discriminated chicken breeds, while hierarchical cluster analysis (HCA) further resolved them into two major clusters with distinct sub-clusters, reflecting variation in DNA biochemical composition. In contrast, GBS analysis identified 1484 common SNPs; however, PCA based on SNP data showed limited resolution in clearly separating breeds, despite revealing similar clustering trends. Overall, the results highlight the strong discriminatory power of SR-FTIR spectroscopy for rapid and effective classification of native chicken breeds at the molecular level, outperforming SNP-based differentiation under the current marker density. This study provides novel insights into the application of synchrotron-based spectroscopic techniques in poultry genetics and contributes valuable baseline information for the conservation and utilization of Lao native chicken genetic resources.

Breed classification↗

PubMed2006

Discrete steps in sensing of beta-lactam antibiotics by the BlaR1 protein of the methicillin-resistant Staphylococcus aureus bacterium.

Chemical sensing by cell-surface receptors to effect signal transduction is a ubiquitous biological event. Despite extensive structural biochemical study, detailed knowledge of how signal transduction occurs is largely lacking. We report herein a kinetic and structural study, obtained by stopped-flow IR spectroscopy, of the activation of the BlaR1 receptor of the Staphylococcus aureus bacterium by beta-lactam antibiotics. The cell-surface BlaR1 receptor alerts the bacterium to the presence of beta-lactam antibiotics, resulting in expression of the gene for a beta-lactamase enzyme. This enzyme hydrolytically destroys the remaining beta-lactam antibiotics. IR spectroscopic interrogation of the beta-lactam-BlaR1 receptor reaction has allowed the simultaneous measurement of the chemical events of receptor recognition of the beta-lactam and the characterization of the conformational changes in the BlaR1 receptor that result. The key chemical events in beta-lactam recognition are serine acylation and subsequent irreversible decarboxylation of the BlaR1 active site lysine carbamate. Both events are observed by stopped-flow IR kinetics and (13)C isotope-edited IR spectroscopy. The secondary structural changes in the BlaR1 receptor conformation that occur as a consequence of this acylation/decarboxylation are predicted to correlate to the signal transduction event accomplished by this receptor.

Acylation↗

PubMed2006

Elongated oligomers assemble into mammalian PrP amyloid fibrils.

In prion diseases, the mammalian prion protein PrP is converted from a monomeric, mainly alpha-helical state into beta-rich amyloid fibrils. To examine the structure of the misfolded state, amyloid fibrils were grown from a beta form of recombinant mouse PrP (residues 91-231). The beta-PrP precursors assembled slowly into amyloid fibrils with an overall helical twist. The fibrils exhibit immunological reactivity similar to that of ex vivo PrP Sc. Using electron microscopy and image processing, we obtained three-dimensional density maps of two forms of PrP fibrils with slightly different twists. They reveal two intertwined protofilaments with a subunit repeat of approximately 60 A. The repeating unit along each protofilament can be accounted for by elongated oligomers of PrP, suggesting a hierarchical assembly mechanism for the fibrils. The structure reveals flexible crossbridges between the two protofilaments, and subunit contacts along the protofilaments that are likely to reflect specific features of the PrP sequence, in addition to the generic, cross-beta amyloid fold.

Amyloid↗