Selection of an efficient in vitro micropropagation and regeneration system for potato (Solanum tuberosum L.) cultivar Desirée

Sprouts of about 40 to 80 mm length were excised, surface sterilized with 70% CloroxR and cultured on solid full-strength Murashige and Skoog (MS) medium. Shoot nodal segments (1.0 cm) from in vitro plantlets (2 to 4 weeks old) were multiplied through periodic subculturing on full-strength MS medium with 30 g/L sucrose, 100 ml/L myo-inositol and 0.5 ml/L silver thiosulfate. The shoots were rooted on the same medium. Microtubers were stimulated on MS medium supplemented with 80 g/L sucrose, 100 ml/L myo-inositol and 5 ml/L benzyl adenine. They generally originate on aerial etiolated shoots producing . 1.0 } 0.5 microtuber/explant with diameter approx. 3 to 10 mm. Shoot regeneration was performed from  tuber discs, internodes and leaf explants using 6 different media. Different regeneration capacities were  observed by the explants along 60 days. The average number of shoots was highest from tuber discs (6.2)  than from leaf explants (2.6) which exceeds about three times; no shoot from internode explants cultured on the various media. Regenerated plantlets produced from both tuber discs and leaf explants exhibited random amplification of polymorphic DNA (RAPD) analysis using five selected primers to detect  somaclonal variation. All the morphological variants were excluded. One of the regenerated plantlet  derived from leaf-explants was true-to-type to the main in vitro plantlet, so it will be used as a source of explants for transformation experiments. The other regenerated plantlets derived from leaf explants and tuber discs show the presence and/or absence of polymorphic bands. Results also showed that  microtubers were initiated on the etiolated shoots of the regenerants at the first 10 days. The etiolated shoots induced about 2.6 } 0.6 and 2.2 } 0.5 microtuber/explants.Key words: Solanum tuberosum L., seed tuber, sprouting, micropropagation, microtubers, explants, regeneration, random amplification of polymorphic DNA (RAPD)

Multiple-input multiple-output causal strategies for gene selection

Traditional strategies for selecting variables in high dimensional classification problems aim to find sets of maximally relevant variables able to explain the target variations. If these techniques may be effective in generalization accuracy they often do not reveal direct causes. The latter is essentially related to the fact that high correlation (or relevance) does not imply causation. In this study, we show how to efficiently incorporate causal information into gene selection by moving from a single-input single-output to a multiple-input multiple-output setting.Journal ArticleResearch Support, N.I.H. ExtramuralResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Molecular mechanism for 3:1 subunit stoichiometry of rod cyclic nucleotide-gated ion channels

Molecular determinants of ion channel tetramerization are well characterized, but those involved in heteromeric channel assembly are less clearly understood. The heteromeric composition of native channels is often precisely controlled. Cyclic nucleotide-gated (CNG) channels from rod photoreceptors exhibit a 3:1 stoichiometry of CNGA1 and CNGB1 subunits that tunes the channels for their specialized role in phototransduction. Here we show, using electrophysiology, fluorescence, biochemistry, and X-ray crystallography, that the mechanism for this controlled assembly is the formation of a parallel 3-helix coiled-coil domain of the carboxy-terminal leucine zipper region of CNGA1 subunits, constraining the channel to contain three CNGA1 subunits, followed by preferential incorporation of a single CNGB1 subunit. Deletion of the carboxy-terminal leucine zipper domain relaxed the constraint and permitted multiple CNGB1 subunits in the channel. The X-ray crystal structures of the parallel 3-helix coiled-coil domains of CNGA1 and CNGA3 subunits were similar, suggesting that a similar mechanism controls the stoichiometry of cone CNG channels

Gentamicin Rapidly Inhibits Mitochondrial Metabolism in High-Frequency Cochlear Outer Hair Cells

Aminoglycosides (AG), including gentamicin (GM), are the most frequently used antibiotics in the world and are proposed to cause irreversible cochlear damage and hearing loss (HL) in 1/4 of the patients receiving these life-saving drugs. Akin to the results of AG ototoxicity studies, high-frequency, basal turn outer hair cells (OHCs) preferentially succumb to multiple HL pathologies while inner hair cells (IHCs) are much more resilient. To determine if endogenous differences in IHC and OHC mitochondrial metabolism dictate differential sensitivities to AG-induced HL, IHC- and OHC-specific changes in mitochondrial reduced nicotinamide adenine dinucleotide (NADH) fluorescence during acute (1 h) GM treatment were compared. GM-mediated decreases in NADH fluorescence and succinate dehydrogenase activity were observed shortly after GM application. High-frequency basal turn OHCs were found to be metabolically biased to rapidly respond to alterations in their microenvironment including GM and elevated glucose exposures. These metabolic biases may predispose high-frequency OHCs to preferentially produce cell-damaging reactive oxygen species during traumatic challenge. Noise-induced and age-related HL pathologies share key characteristics with AG ototoxicity, including preferential OHC loss and reactive oxygen species production. Data from this report highlight the need to address the role of mitochondrial metabolism in regulating AG ototoxicity and the need to illuminate how fundamental differences in IHC and OHC metabolism may dictate differences in HC fate during multiple HL pathologies

Genomics of alkaliphiles

Alkalinicity presents a challenge for life due to a “reversed” proton gradient that is unfavourable to many bioenergetic processes across the membranes of microorganisms. Despite this, many bacteria, archaea, and eukaryotes, collectively termed alkaliphiles, are adapted to life in alkaline ecosystems and are of great scientific and biotechnological interest due to their niche specialization and ability to produce highly stable enzymes. Advances in next-generation sequencing technologies have propelled not only the genomic characterization of many alkaliphilic microorganisms that have been isolated from nature alkaline sources but also our understanding of the functional relationships between different taxa in microbial communities living in these ecosystems. In this review, we discuss the genetics and molecular biology of alkaliphiles from an “omics” point of view, focusing on how metagenomics and transcriptomics have contributed to our understanding of these extremophiles.https://link.springer.com/bookseries/10hj2021BiochemistryGeneticsMicrobiology and Plant Patholog