Retinestatin, a Polyol Polyketide from a Termite Nest-Derived Streptomyces sp.

A new polyol polyketide, named retinestatin (1), was obtained and characterized from the culture of a Streptomyces strain, which was isolated from a subterranean nest of the termite Reticulitermes speratus kyushuensis Morimoto. The planar structure of 1 was elucidated on the basis of the cumulative analysis of ultraviolet, infrared, mass spectrometry, and nuclear magnetic resonance spectroscopic data. The absolute configuration of 1 at 12 chiral centers was successfully assigned by employing a J-based configuration analysis in combination with ROESY correlations, a quantum mechanics-based computational approach to calculate NMR chemical shifts, and a 3 min flash esterification by Mosher's reagents followed by NMR analysis. Biological evaluation of retinestatin (1) using an in vitro model of Parkinson's disease revealed that 1 protected SH-SY5Y dopaminergic cells from MPP+-induced cytotoxicity, indicating its neuroprotective effects.

Corpuscles of Stannius development requires FGF signaling.

The corpuscles of Stannius (CS) represent a unique endocrine organ of teleostean fish that secrets stanniocalcin-1 (Stc1) to maintain calcium homeostasis. Appearing at 20-25 somite stage in the distal zebrafish pronephros, stc1-expressing cells undergo apical constriction, and are subsequently extruded to form a distinct gland on top of the distal pronephric tubules at 50 â€‹h post fertilization (hpf). Several transcription factors (e.g. Hnf1b, Irx3b, Tbx2a/b) and signaling pathways (e.g. Notch) control CS development. We report now that Fgf signaling is required to commit tubular epithelial cells to differentiate into stc1-expressing CS cells. Inhibition of Fgf signaling by SU5402, dominant-negative Fgfr1, or depletion of fgf8a prevented CS formation and stc1 expression. Ablation experiments revealed that CS have the ability to partially regenerate via active cell migration involving extensive filopodia and lamellipodia formation. Activation of Wnt signaling curtailed stc1 expression, but had no effect on CS formation. Thus, our observations identify Fgf signaling as a crucial component of CS cell fate commitment.

DS86760016, a Leucyl-tRNA Synthetase Inhibitor, Is Active against Mycobacterium abscessus.

Benzoxaboroles are a new class of leucyl-tRNA synthetase inhibitors. Epetraborole, a benzoxaborole, is a clinical candidate developed for Gram-negative infections and has been confirmed to exhibit favorable activity against a well known pulmonary pathogen, Mycobacterium abscessus. However, according to ClinicalTrials.gov, in 2017, a clinical phase II study on the use of epetraborole to treat complicated urinary tract and intra-abdominal infections was terminated due to the rapid emergence of drug resistance during treatment. Nevertheless, epetraborole is in clinical development for nontuberculous mycobacteria (NTM) disease especially for Mycobacterium avium complex-related pulmonary disease (MAC-PD). DS86760016, an epetraborole analog, was further demonstrated to have an improved pharmacokinetic profile, lower plasma clearance, longer plasma half-life, and higher renal excretion than epetraborole in animal models. In this study, DS86760016 was found to be similarly active against M. abscessus in vitro, intracellularly, and in zebrafish infection models with a low mutation frequency. These results expand the diversity of druggable compounds as new benzoxaborole-based candidates for treating M. abscessus diseases.

Synergistic Effect of Q203 Combined with PBTZ169 against Mycobacterium tuberculosis.

Q203 is a first-in-class drug candidate against Mycobacterium tuberculosis. In its recently completed phase 2 clinical trial, Q203 reduced the number of live M. tuberculosis cells in a dose-dependent manner. This orally active small molecule blocks M. tuberculosis growth by inhibiting the cytochrome bc1 complex, which consequently inhibits the synthesis of ATP. Here, we studied the interaction profiles of Q203 with several antituberculosis drugs or drug candidates (specifically, bedaquiline, PBTZ169, PA-824, OPC-67683, SQ109, isoniazid, rifampin, streptomycin, and linezolid) using the checkerboard method, based on resazurin microtiter assays (REMAs). In the assay, none of the interactions between Q203 and the tested drugs were antagonistic, and most of the interactions were additive. However, the interaction between Q203 and PBTZ169 was synergistic, with a fractional inhibitory concentration index of 0.5. Furthermore, Q203 (one-half the MIC50) and PBTZ169 (one-half the MIC50) inhibited more bacterial growth on an agar plate compared to the dimethyl sulfoxide (DMSO) control. This synergistic effect was no longer effective when the Q203-PBTZ169 combination was tested against an M. tuberculosis mutant containing a T313A mutation causing resistance to Q203, suggesting that QcrB inhibition is integral to the Q203-PBTZ169 interaction. Thus, this synergy is not an off-target mechanism. Zebrafish (Danio rerio)-Mycobacterium marinum infection and a curing model further validated the synergistic effect of Q203 and PBTZ169 in vivo. In this study, the synergy between these two new antituberculosis drugs, Q203 and PBTZ169, is an important finding that could lead to the development of a new TB regimen.

Gwanakosides A and B, 6-Deoxy-α-l-talopyranose-Bearing Aromatic Metabolites from a Streptomyces sp. and Coculture with Pandoraea sp.

Single-strain cultivation of a mountain soil-derived Streptomyces sp. GA02 and its coculture with Pandoraea sp. GA02N produced two aromatic products, gwanakosides A and B (1 and 2, respectively). Their spectroscopic analysis revealed that 1 is a new dichlorinated naphthalene glycoside and 2 is a pentacyclic aromatic glycoside. The assignment of the two chlorine atoms in 1 was confirmed by the analysis of its band-selective CLIP-HSQMBC spectrum. The sugars in the gwanakosides were identified as 6-deoxy-α-l-talopyranose based on 1H-1H coupling constants, Rotating frame Overhauser enhancement spectroscopy (ROESY) NMR correlations, and chemical derivatization followed by spectroscopic and chromatographic analyses. The absolute configuration of 2, whose production was enhanced approximately 100-fold in coculture, was proposed based on a quantum mechanics-based chemical shift analysis method, DP4 calculations, and the chemically determined configuration of 6-deoxy-α-l-talopyranose. Gwanakoside A displayed inhibitory activity against pathogenic bacteria, including Staphylococcus aureus (MIC = 8 µg/mL) and Mycobacterium tuberculosis (MIC50 = 15 µg/mL), and antiproliferative activity against several human cancer cell lines (IC50 = 5.6-19.4 µM).

Effect of nucleocytoplasmic ratio on the in vitro porcine embryo development after in vitro fertilization or parthenogenetic activation.

This study was conducted to examine whether the nuclear to cytoplasmic (N/C) ratio had any influence on the timing of embryo compaction and blastocoel formation, as well as formation rate and quality of blastocyst. First, we produced embryos with increased N/C ratio by removal of approximately one-third of the cytoplasm and with decreased N/C ratio by doubling the oocyte cytoplasm with an enucleated oocyte. The initiation of compaction and cavitation in reduced cytoplasm group was significantly earlier (P < 0.05) compared with the control and doubled cytoplasm groups. The rate of blastocysts in the reduced cytoplasm and doubled cytoplasm groups was significantly lower (P < 0.05) compared with the control group. Blastocyst quality in terms of total cell number in the reduced cytoplasm group was significantly lower (P < 0.05) compared with the doubled cytoplasm group, but not different from the control group. Next, we produced embryos with various N/C ratios by oocyte fusion combined with cytochalasin D treatment. The onset of compaction and cavitation in the 2N/2C group (decreased N/C ratio) was significantly delayed (P < 0.05) or had the tendency to be delayed (P = 0.064), respectively, compared with the control group (2N/1C). A significantly higher rate of blastocyst was observed in the 4N/2C group compared with the 1N/1C group (P < 0.05) but not different from the remaining groups. These results demonstrated that an increase in N/C ratio caused an earlier occurrence of morula compaction and blastocyst formation in both in vitro fertilization (IVF) and parthenogenetically activated pig embryos.

Doubling of the cytoplasm volume improves the developmental competence of porcine oocytes injected with freeze-dried somatic cells.

In the present study using pig cells, we examined the effect of the cryoprotectant trehalose on the DNA integrity of freeze-dried cells. We then investigated whether donor cell types and storage duration had impact on DNA integrity in freeze-dried cells or developmental competence of oocytes injected with freeze-dried somatic cells. We also examined whether double cytoplasm nuclear transfer (DCNT) would improve developmental competence of such oocytes. Furthermore, using a PCR-based method for sex identification, we determined whether the blastocysts obtained had actually been generated from the freeze-dried cells. It was found that, for a short storage duration at low temperature, trehalose had no beneficial effect on protection from DNA damage, and that donor cell type had no effect on the DNA integrity of freeze-dried somatic cells or the developmental competence of oocytes injected with them. We also confirmed that all of the blastocysts obtained following nuclear transfer were of freeze-dried somatic cell origin. Storage of freeze-dried somatic cells for up to 1 year at low temperature did not degrade DNA integrity in comparison with storage for 1 month, 1 week or 1 day. Following injection of freeze-dried cells, the proportion of oocytes that developed to blastocysts after storage for up to 1 year was similar to that after storage for 1 month, 1 week or 1 day. Moreover, DCNT significantly improved the developmental competence of oocytes treated in this way. In summary, using DCNT, we have demonstrated that freeze-dried porcine somatic cells subjected to long-term storage at 4 °C have nearly the same potential to develop to blastocysts as non-freeze-dried cells.

Establishment of porcine nuclear transfer-derived embryonic stem cells using induced pluripotent stem cells as donor nuclei.

We investigated whether sequential reprogramming via porcine induced pluripotent stem cells (piPSCs) or exposure to oocyte cytoplasm following nuclear transfer could generate nuclear transfer-derived ESCs (piPSCs-ntESCs). Nuclear transfer embryos were reconstructed with piPSCs possessing a ZsGreen fluorescent marker for expression of exogenous Nanog and Lin28. Reconstructed oocytes developed to morphologically normal 8-cell/morulae (35/93, 37.6%) and blastocysts (12/93, 12.9%). Although most green fluorescent protein-positive blastocysts showed efficient outgrowth (8/10, 80%), none formed primary colonies and all cultures degenerated. Conversely, 15% of fluorescent positive 8-cell/morula stage embryos showed outgrowth (6/40), with three forming primary colonies (7.5%). All three were expanded and maintained as piPSC-ntESC lines. These cell lines expressed stem cell marker genes and proteins. Despite inactivation of one X chromosome, all piPSC-ntESC lines formed teratomas comprising derivatives from all three embryonic germ layers. Strong SSEA1, 3, and 4 expression was detected at the 8-cell/morula stage in embryos reconstructed from both piPSCs and porcine embryonic fibroblasts (PEFs). SSEA3 was notably absent from IVF controls at pre-implantation embryo stages. Finally, we attempted to establish ntESCs from 8-cell/morulae reconstructed with PEFs using the same culture conditions as those for piPSC-ntESC derivation. Although eight primary colonies arose from 107 embryos (7.5%), they all degenerated after the first passage culture. Early and sustained expression of key reprogramming regulatory factors may be critical for pluripotent stem cell derivation to derive piPSC-ntESCs from 8-cell/morula stages, while the expression of SSEAs may be involved in the initial stem cell colony formation phases.

Successful activation of rat T lymphocytes by sperm specific antigens in vitro.

Autoimmune orchitis is a condition related to cellular immunity. A disease model involving transfer of T lymphocytes activated by known antigens would be useful for defining pathogenical molecules. Since no method for activating rat T cells using specific antigens is available, we started the study to develop the method. T cells were collected from draining lymph nodes of immunized rats, then co-cultured with syngeneic splenocytes as antigen-presenting cells (APC) in antigen-supplemented medium (= stimulation). The cells were then incubated in medium without antigens and APC (= resting). Repetitive stimulation and resting increased the number of the T cells more than 100-fold. The antigen-specific activation was demonstrated by cell proliferation assay and ELISA assay for interferon gamma. Flow cytometry revealed that > 95% of the cells expressed tumor necrosis factor alpha, a cytokine responsible for autoimmune orchitis. The present method will provide a new procedure to evaluate antigenicity of sperm molecules.

Combined refinements to somatic cell nuclear transfer methods improve porcine embryo development.

The discovery of how to utilize CRISPR (clustered, regularly interspaced, short, palindromic repeats)-Cas (CRISPR-associated) systems for genome modification has accelerated development of the field of genome editing, especially in large animals such as pigs. The low efficiency of somatic cell nuclear transfer (SCNT) is now becoming a major obstacle in the production of genome-edited animals via cell-mediated approaches and improving efficacy of this technique is crucial. In this study, we propose a few simple modifications to a zona-free SCNT protocol that are effective to produce numerous high-quality blastocysts. To refine the SCNT protocol we modified the following steps/factors: 1) culture medium for SCNT embryos, 2) chemical treatment to prevent precocious activation of the manipulated/reconstructed oocytes and 3) donor cell serum starvation treatment. Although changes in each of these steps only resulted in small improvements, the combination of all modifications altogether significantly enhanced developmental competence of SCNT embryos. Our modified method yielded approximately three times greater blastocyst formation rates. Moreover, resulting blastocysts had roughly twice as many cells as compared to blastocysts produced by the conventional SCNT method. With these significant in vitro improvements, our refined SCNT method is potentially suited for use in the production of genome edited pigs.

Vitrification of porcine cumulus-oocyte complexes at the germinal vesicle stage does not trigger apoptosis in oocytes and early embryos, but activates anti-apoptotic Bcl-XL gene expression beyond the 4-cell stage.

The aim of the present study was to clarify whether or not our vitrification procedure at the germinal vesicle (GV)-stage triggers the apoptotic cascade in oocytes and subsequent embryos. Immature porcine cumulus-oocyte complexes were either vitrified and warmed (vitrified group) or subjected to cryoprotectant agents (CPA group) or cultured without any treatment (control). Oocytes of all treatment groups were subjected to in vitro maturation (IVM), fertilization, and embryo culture. Apoptosis was assayed in live oocytes at the end of IVM culture and in cleavage-stage embryos after in vitro fertilization (IVF). We detected similar frequencies of DNA fragmentation, levels of caspase activity, phosphatidylserine externalization, and mRNA levels for pro-apoptotic Bax and CASP3 genes in oocytes at the end of IVM and in early embryos among all groups. However, in the vitrified group, the anti-apoptotic Bcl-XL gene was upregulated in 4-8 cell embryos, which caused an 8-fold significant increase in the Bcl-XL/Bax mRNA ratio compared with the control and CPA groups (P < 0.05). In conclusion, vitrification of porcine oocytes at the GV stage by our method did not trigger the apoptotic cascade in oocytes and subsequent embryos but triggered the upregulation of the anti-apoptotic Bcl-XL gene in embryos.

Effects of vitrification of cumulus-enclosed porcine oocytes at the germinal vesicle stage on cumulus expansion, nuclear progression and cytoplasmic maturation.

Although offspring have been produced from porcine oocytes vitrified at the germinal vesicle (GV) stage, the rate of embryo development remains low. In the present study, nuclear morphology and progression, cumulus expansion, transzonal projections (TZPs), ATP and glutathione (GSH) levels were compared between vitrified cumulus-oocyte complexes (COCs) and control COCs (no cryoprotectant treatment and no cooling), as well as a toxicity control (no cooling). Vitrification was performed with 17.5% (v/v) ethylene glycol and 17.5% (v/v) propylene glycol. Vitrification at the GV stage caused premature meiotic progression, reflected by earlier GV breakdown and untimely attainment of the MII stage. However, cytoplasmic maturation, investigated by measurement of ATP and GSH levels, as well as cumulus expansion, proceeded normally despite detectable damage to TZPs in vitrified COCs. Moreover, treatment with cryoprotectants caused fragmentation of nucleolus precursor bodies and morphological changes in F-actin from which oocytes were able to recover during subsequent IVM culture. Reduced developmental competence may be explained by premature nuclear maturation leading to oocyte aging, although other mechanisms, such as initiation of apoptosis and reduction of cytoplasmic mRNA, can also be considered. Further research will be required to clarify the presence and effects of these phenomena during the vitrification of immature COCs.

Improvement of the developmental competence of porcine oocytes collected from early antral follicles by cytoplast fusion.

In the present study, we propose an alternative technique called cytoplast fusion to improve the maturation rate and developmental competence of growing oocytes collected from early antral follicles in pigs. We examined whether the fusion of a growing oocyte with the cytoplast from a fully-grown oocyte (CFR group) could better promote maturation and developmental competence of the growing oocyte compared to germinal vesicle (GV) transfer (GVTR group). After 44 h of in vitro maturation (IVM), most growing oocytes (GR group) were still arrested at the GV stage (64.0 ± 5.1%); this number was significantly higher (P < 0.01) than that of the other groups. No matured oocyte was observed in the GR group. The maturation rate of GVTR oocytes was significantly improved (18.8 ± 3.5%) compared with that of growing oocytes. The proportion of oocytes that reached the metaphase-II (M-II) stage in the CFR group (37.8 ± 2.0%) was significantly higher (P < 0.05) than that in the GVTR group, although still lower than that in the control group (75.2 ± 4.4%). No blastocyst was derived from growing oocytes. Among in vitro fertilized GVTR oocytes, 3.0 ± 1.9% developed into blastocysts; however, this percentage showed an insignificant increase compared with the GR group. On the other hand, the percentage of CFR embryos that developed into blastocysts (12.0 ± 4.3%) was significantly higher than that of GR embryos (0.0%), although still lower than that of control embryos (27.0 ± 5.5%). Total cell number in blastocysts in the GVTR group (23.3 ± 6.9) was significantly lower (P < 0.05) than that in the control group (50.4 ± 5.0). Meanwhile, the total cell number in blastocysts derived from CFR oocytes (36.3 ± 4.8) was comparable to that of the control group. In summary, cytoplast fusion significantly improves maturation rate and developmental competence of growing oocytes compared with GV transfer.

Leukemia inhibitory factor promotes porcine oocyte maturation and is accompanied by activation of signal transducer and activator of transcription 3.

We produced recombinant porcine leukemia inhibitory factor (pLIF) and examined its effect on in vitro maturation (IVM) of porcine oocytes and their developmental competence after in vitro fertilization. Porcine cumulus-oocyte complexes (COCs) were matured in a medium supplemented with pLIF during the first 22 hr, last 22 hr, or entire 44 hr duration of IVM. Oocytes in all groups tended to show enhanced nuclear maturation rates by the metaphase II (MII) stage (76.1%, 82.1%, and 86.6%, respectively) compared to the without-pLIF treatment group (69.6%, control). A significant increase in MII rate (P < 0.05) and obvious induction of cumulus expansion were observed over the whole time span (44 hr) in the IVM group. When cumulus cells were removed at 22 hr and denuded oocytes were further cultured, pLIF showed no effect on maturation rate. Oocytes matured in pLIF-supplemented medium showed a tendency for more rapid blastocyst development (21.1% vs. 16.2%, P = 0.0715). Examination of transcripts and proteins of the LIF signaling pathway in COCs revealed that LIF, LIF receptors, and signal transducer and activator of transcription 3 (STAT3) are present in both cumulus cells and oocytes. The amount of phosphorylated STAT3 (p-STAT3) markedly increased in both cumulus cells and oocytes cultured in pLIF-supplemented media, although oocyte p-STAT3 disappeared after 44 hr of IVM. These results suggest that the LIF/STAT3 pathway is functional during IVM of porcine oocytes, and supplementing pLIF in the IVM medium can improve oocyte maturation by activating this pathway.

Prevalence and determinants of household medicine storage in Vietnam: A community-based cross-sectional study.

Objectives: The COVID-19 pandemic has significantly impacted individual health, potentially increasing the demand for home medicine storage. However, inappropriate household medicine storage can lead to drug waste and unnecessary hazards. This study aimed to explore the prevalence of and identify the factors that predict medicine storage in Vietnamese households. Methods: A community-based cross-sectional study was conducted with 800 households in Danang, Vietnam. A multi-stage sampling method was applied in this study. The data collection tool was modified from previous studies and consisted of three sections: household head characteristics, household characteristics, and medicine storage practice. Bivariable and multivariable binary logistic regression analyses were used to identify the factors influencing medicine storage at a p-value of less than 0.05. Results: Among 800 households surveyed, 71.6% stored medicine. Analgesics-antipyretics were the most common type of medicine stored (80.8%). 90.1% of households obtained their medicines from private pharmacies, 68.1% of households stored medicine for future use and 58.8% had a home medicine cabinet. 9.4% of households did not store medicine in the appropriate packaging and 19.4% of households did not check the expiry date of their medicine. Educational level (AOR = 2.74; 95% CI = 1.84-4.06), income (AOR = 11.38; 95% CI = 1.46-88.79), presence of chronic illnesses (AOR = 12.44; 95% CI = 7.20-21.21), presence of children (AOR = 2.36; 95% CI = 1.56-3.58), presence of healthcare professionals (AOR = 2.14; 95% CI = 1.28-3.56) were predictors of the medicine storage. Conclusions: The current study found a high prevalence of household medication storage and some inappropriate storage behaviors. Therefore, attention should be given to develop effective interventions and policies to promote safe and appropriate storage practices.

Exploring antibiotic resistance mechanisms in Mycobacterium abscessus for enhanced therapeutic approaches.

Mycobacterium abscessus, a leading cause of severe lung infections in immunocompromised individuals, poses significant challenges for current therapeutic strategies due to resistance mechanisms. Therefore, understanding the intrinsic and acquired antibiotic resistance of M. abscessus is crucial for effective treatment. This review highlights the mechanisms employed by M. abscessus to sustain antibiotic resistance, encompassing not only conventional drugs but also newly discovered drug candidates. This comprehensive analysis aims to identify novel entities capable of overcoming the notorious resistance exhibited by M. abscessus, providing insights for the development of more effective therapeutic interventions.

Ectopic antenna induction by overexpression of CG17836/Xrp1 encoding an AT-hook DNA binding motif protein in Drosophila.

Drosophila imaginal discs are an excellent model system for studies of developmental plasticity. In imaginal discs, most cells adhere strictly to their specific identity, but some cells undergo transdetermination, a process wherein the determined identity switches to another disc-specific identity. In this study, we performed gain-of-function screening and identified a gene, CG17836/Xrp1, that induces ectopic antennae in the eye field upon overexpression at the early eye disc stage. An essential factor in the distalization process, Distalles, and its upstream regulators Wingless, Hedgehog, and Decapentaplegic, are ectopically induced by CG17836/Xrp1 overexpression in eye discs, and this provides molecular evidence of the formation of ectopic antennae. Further, forced expression of CG17836/Xrp1 induced severe cell-proliferation defects. These findings suggest that CG17836/Xrp1 is involved in the regulation of cell proliferation in eye discs and affects disc identity specification.

Downregulation of histone methyltransferase genes SUV39H1 and SUV39H2 increases telomere length in embryonic stem-like cells and embryonic fibroblasts in pigs.

Telomere is a nucleoprotein structure at the ends of chromosomes that helps to protect the ends of chromosomes from being fused with other chromosomes. Knockout of histone methyltransferases Suv39h1 and Suv39h2 increases the telomere length in murine cells, whereas downregulation of SUV39H1 and SUV39H2 genes decreases the telomere length in human cells, suggesting that telomere biology is different among mammalian species. However, epigenetic regulation of the telomere has not been studied in mammals other than the human and mouse. In the present study, the effect of knockdown of SUV39H1 and SUV39H2 genes on telomere length was examined in porcine embryonic stem-like cells (pESLCs) and porcine embryonic fibroblasts (PEFs). The telomeres in SUV39H1 and SUV39H2 knockdown (SUV39KD) pESLCs (37.1 ± 0.9 kb) were longer (P<0.05) compared with those of the control (33.0 ± 0.7 kb). Similarly, SUV39KD PEFs had longer telomeres (22.1 ± 0.4 kb; P<0.05) compared with the control (17.8 ± 1.1 kb). Telomerase activities were not different between SUV39KD pESLCs (10.4 ± 1.7) and the control (10.1 ± 1.7) or between SUV39KD PEFs (1.0 ± 0.3) and the control (1.0 ± 0.4), suggesting that telomerase activities did not contribute to the telomere elongation in SUV39KD pESLCs and SUV39KD PEFs. Relative levels of trimethylation of histone H3 lysine 9 and expressions of DNMT1, DNMT3A and DNMT3B were decreased in SUV39KD cells, suggesting that telomere lengthening in SUV39KD pESLCs and SUV39KD PEFs might be not only related to the loss of histone modification marks but also linked to the decrease in DNA methyltransferase in pigs.

Fertilization ability of porcine oocytes reconstructed from ooplasmic fragments produced and characterized after serial centrifugations.

Mitochondria are reported to be critical in in vitro maturation of oocytes and subsequent embryo development after fertilization, but their contribution for fertilization has not been investigated in detail. In the present study, we investigate the contribution of mitochondria to fertilization using reconstructed porcine oocytes by fusion of ooplasmic fragments produced by serial centrifugations (centri-fusion). Firstly, we evaluated the characteristics of ooplasmic fragments. Three types of fragments were obtained by centrifugation of porcine oocytes matured in vitro for 46 h: brownish (B), transparent (T) and large (L) fragments containing both B and T parts in a fragment. The production efficiencies of these types of fragments were 71.7, 91.0 and 17.8 fragments/100 oocytes, respectively. In experiments, L fragments were excluded because they contained both brownish and transparent components that were apparently intermediate between B and T fragments. Observations by confocal microscopy after staining with MitoTracker Red CMXRos® and transmission electron microscopy revealed highly condensed active mitochondria in B fragments in contrast to T fragments that contained only sparse organelles. We reconstructed oocytes by fusion of a karyoplast and two cytoplasts from B and T fragments (B and T oocytes, respectively). The B oocytes showed higher sperm penetration (95.8%) and male pronuclear formation rates (94.2%) by in vitro fertilization than T oocytes (66.7% and 50.0%, respectively). These results suggest that the active mitochondria in oocytes may be related to their ability for fertilization.

CRISPR Interference-Based Inhibition of MAB_0055c Expression Alters Drug Sensitivity in Mycobacterium abscessus.

There is an unmet medical need for effective treatments against Mycobacterium abscessus infections. Although advanced molecular genetic tools to validate drug targets and resistance of M. abscessus exist, the practical design and construction of plasmids are relatively laborious and time-consuming. Thus, for this purpose, we used CRISPR interference (CRISPRi) combined with catalytically deactivated Cas9 to inhibit the gene expression of a predicted LysR-type transcriptional regulator gene, MAB_0055c, in M. abscessus and evaluated its contribution to the development of drug resistance. Our results showed that silencing the MAB_0055c gene lead to increased rifamycin susceptibility depending on the hydroquinone moiety. These results demonstrate that CRISPRi is an excellent approach for studying drug resistance in M. abscessus. IMPORTANCE In this study, we utilized CRISPR interference (CRISPRi) to specifically target the MAB_0055c gene in M. abscessus, a bacterium that causes difficult-to-treat infections. The study found that silencing the gene lead to increased rifabutin and rifalazil susceptibility. This study is the first to establish a link between the predicted LysR-type transcriptional regulator gene and antibiotic resistance in mycobacteria. These findings underscore the potential of using CRISPRi as a tool for elucidating resistance mechanisms, essential drug targets, and drug mechanisms of action, which could pave the way for more effective treatments for M. abscessus infections. The results of this study could have important implications for the development of new therapeutic options for this challenging-to-treat bacterial infection.