Standard Laboratory Conditions Research Articles

Meta-analysis of experimental studies of the effect of melatonin monotherapy on the levels of thyroid hormones and glucocorticoids in rats kept under standard condition

Melatonin is known to modulate circadian and seasonal rhythms in metabolism, reproduction, and behavior. However, the effect of exogenous melatonin supplementation on the functioning of the thyroid and adrenal glands in species without a clear seasonality in reproduction is still unclear. Using a meta-analysis of publications, to investigate the effect of melatonin monotherapy on the concentrations of pituitary thyroid-stimulating hormone, thyroid hormones (TG), pituitary adrenocorticotropic hormone and corticosterone (CS) in rats kept under standard laboratory conditions. In our work, using the Review Manager 5.3 program, we conducted a meta-analysis of publications examining the effect of melatonin monotherapy on the functioning of the thyroid gland (22 papers) and adrenal glands (20 papers) in rats kept under standard conditions. According to the results of our meta-analysis, the effects of melatonin on the levels of TG and CS depend on the dose and duration of therapy. A decrease in TG and CS was associated with therapy lasting no more than 4-5 weeks and with high doses of melatonin. An increase in CS and a trend toward increased TG levels were observed with longer therapy. However, a few studies have observed a decrease in TG with very long-term melatonin therapy (≥32 weeks). Among all TGs, total thyroxine (T4) showed maximum sensitivity to exogenous melatonin, which indicates the influence of melatonin on the secretory function of the thyroid gland. In addition, melatonin increased the relative weight of the adrenal glands. There was no convincing evidence that the effects of melatonin were influenced by the route and timing of administration, or the timing of blood sampling. As a result, exogenous melatonin can modulate TG and CS levels, even in species without a clear seasonality in reproductive function.

Chemical Diversity of Aspergillus alliaceus Phenotypes: Discovery of Brominated Bianthrones with Activity against Triple-Negative Breast Cancer Cell Lines.

Marine-derived fungi have emerged as a source for novel metabolites with a broad range of bioactivities. However, accessing the full potential of fungi under standard laboratory conditions remains challenging. LC-MS-based metabolomics in combination with varied culture conditions is a fast and powerful tool to detect new metabolites. Here, three developmental forms of the marine-derived fungus Aspergillus alliaceus were analyzed and 14 fungal metabolites, including new brominated polyketides (11-14) were isolated. Structure elucidation relied mainly on 1D and 2D NMR techniques and was supported by low- and high-resolution mass spectrometry and DFT-based computations. We sequenced the A. alliaceus genome, identified the bianthrone-producing biosynthetic gene cluster, and conducted expression analysis on genes involved in sexual development and biosynthesis. The NCI-60 cell line panel revealed selective in vitro activity against triple-negative breast cancer (TNBC) for the halogenated allianthrones and their full antiproliferative and cytotoxic effects were evaluated in five TNBC cell lines.

Genotoxicity Of The Herbicide Picloram (TORDON ® 24K) on tadpoles of Boana pulchella (Amphibia, Anura, Hylidae)

Picloram (PIC) is an herbicide widely used in Uruguay to control weeds, especially in forest crops. In the present study, we evaluate the acute toxicity and genotoxicity of formulated 24.9% PIC-based Tordon®24K on Boana pulchella tadpoles under standard laboratory conditions. In the acute toxicity test we use mortality as the endpoint and we obtained a 48-h LC50 of 16.5 mg/L, LOEC 14.5 mg/L, and NOEC 12.5 mg/L. We determined genotoxicity in GS36 tadpoles exposed to sublethal concentrations of 8.5 (NOEC/1.5) and 12.5 mg/L (NOEC) PIC using micronucleus frequency (MN) and occurrence of nuclear abnormalities (AN) as endpoints. We noticed a significant increase in the frequency of MN and AN in all treatments tested at sublethal concentrations. Our findings demonstrate the genotoxic effects of this herbicide, which represent a danger to amphibians that inhabit agroecosystems. Based on the results obtained and considering that Boana pulchella is not a threatened species and has a wide distribution in the Uruguayan territory and the Pampa Biome, it could be considered a reference organism in environmental monitoring programs in the region.

Fabrication of solar cells from polymer composite (3-Hexylthiophene-co-Thiophene) with Ag nanoparticles and study of electrical properties and efficiency

This study aims to prepare nano-polymer materials that contribute to improving the electrical properties and improving the properties and efficiency of solar cells. Also, the prepared materials are inexpensive compared to solar cells prepared from inorganic materials such as silicon and germanium. This study deals with the effect of a polymer layer containing pure polymer of 3-Hexylthiophene and Thiophenein combination with silver nanoparticles on the electrical properties relevant to solar cell applications. The polymer of 3-Hexylthiophene and Thiophene was prepared individually, then a polymer composite (3-Hexylthiophene-co-Thiophene) was made. after that then a Core-Shell of (3-hexylthiophene - CO-Thiophene) @ Ag Nanoparticles was made, after which two-layer and three-layer solar cells were made from the prepared samples. The polymers were manufactured using the additive polymerization method using chloroform (CHCl3) solvent and were subsequently characterized. The research focused on the electrical properties of the pure polymer (P3HT@Thio) doped with silver nanoparticles and its efficiency, with special attention to its application in solar cells. We found the best results in the two-layer structure. Current-voltage (I-V) measurements were conducted under illumination at room temperature with varying incident light intensities over a small area. Key parameters such as electrical conductivity, activation energy, open-circuit voltage (Voc), short-circuit current density (Jsc), maximum power point parameters (JP, VP), fill factor (FF), and power conversion efficiency (η) were calculated for all samples under standard laboratory conditions. The results demonstrate that the highest electrical conductivity (2.39x10⁻³ s.cm⁻¹) was achieved with the polymer blend of 70% P3HT-CO-30% PTH doped with 25% silver nanoparticles (Ag NPs). The activation energy, ranging from 0.1448 eV to 0.8537 eV, showed the lowest value at the same polymer blend, likely due to the proximity of the conduction and valence band levels induced by nanoparticle doping. Additionally, the efficiency of the solar cells was assessed, revealing significant improvements in device performance. The optimal efficiency, measured at 10.488%, was observed in the (PEDOT)/ (PCPM+Active Layer) structure. All relevant parameters, including Jsc, Voc, FF, and power conversion efficiency (PCE).

Comparison of machine learning methods for genomic prediction of selected Arabidopsis thaliana traits.

We present a comparison of machine learning methods for the prediction of four quantitative traits in Arabidopsis thaliana. High prediction accuracies were achieved on individuals grown under standardized laboratory conditions from the 1001 Arabidopsis Genomes Project. An existing body of evidence suggests that linear models may be impeded by their inability to make use of non-additive effects to explain phenotypic variation at the population level. The results presented here use a nested cross-validation approach to confirm that some machine learning methods have the ability to statistically outperform linear prediction models, with the optimal model dependent on availability of training data and genetic architecture of the trait in question. Linear models were competitive in their performance as per previous work, though the neural network class of predictors was observed to be the most accurate and robust for traits with high heritability. The extent to which non-linear models exploit interaction effects will require further investigation of the causal pathways that lay behind their predictions. Future work utilizing more traits and larger sample sizes, combined with an improved understanding of their respective genetic architectures, may lead to improvements in prediction accuracy.

Identification and characterization of the siderochelin biosynthetic gene cluster via coculture.

Many microbial biosynthetic gene clusters (BGCs) are inactive under standard laboratory conditions, making characterization of their products difficult. Silent BGCs are likely activated by specific cues in their natural environment, such as the presence of competitors. Growth conditions such as coculture with other microbes, which more closely mimic natural environments, are practical strategies for inducing silent BGCs. Here, we utilize coculture to activate BGCs in nine actinobacteria strains. We observed increased production of the ferrous siderophores siderochelin A and B during coculture of Amycolatopsis strain WAC04611 and Tsukamurella strain WAC06889b. Furthermore, we identified the siderochelin BGC in WAC04611 and discovered that the GntR-family transcription factor sidR3 represses siderochelin production. Deletion of the predicted aminotransferase sidA abolished production of the carboxamides siderochelin A/B and led to the accumulation of the carboxylate siderochelin D. Finally, we deleted the predicted hydroxylase sidB and established that it is essential for siderochelin production. Our findings show that microbial coculture can successfully activate silent BGCs and lead to the discovery and characterization of unknown BGCs for molecules like siderochelin.IMPORTANCESiderophores are vital iron-acquisition elements required by microbes for survival in a variety of environments. Furthermore, many siderophores are essential for the virulence of various human pathogens, making them a possible target for antibacterials. The significance of our work is in the identification and characterization of the previously unknown BGC for the siderophore siderochelin. Our work adds to the growing knowledge of siderophore biosynthesis, which may aid in the future development of siderophore-targeting pharmaceuticals and inform on the ecological roles of these compounds. Furthermore, our work demonstrates that combining microbial coculture with metabolomics is a valuable strategy for identifying upregulated compounds and their BGCs.

Evaluation of Lipid Profile Modulation by Berberis asiatica, Withania somnifera, and Their Synergy in Type 2 Diabetic Wistar Rats.

Introduction Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and hyperglycemia, leading to complications such as dyslipidemia, which increases cardiovascular risks. Current treatments for dyslipidemia often have undesirable side effects. This study aims to evaluate the effects ofBerberis asiatica(BA),Withania somnifera(WS), and their combination in the ratio of 1:1 on the lipid profile in T2DM-induced Wistar rats. Additionally, the study investigates the potential synergistic effects of these two herbs. Materials and methods Mature albino Wistar rats of both sexes were employed, weighing 150-250 g. Rats were obtained from the Central Animal House of Krishna Institute of Medical Sciences and kept under standard laboratory conditions. The study was conducted per theguidelines setby the Committee for Control and Supervision of Experiments on Animals (CCSEA). T2DM was induced using streptozotocin (STZ) and nicotinamide (NIC). Thirteen groups of rats were formed, including normal control (NC), diabetic control (DC), and various treatment groups received varying dosages of BA, WS, their polyherbal combination (PHC), and the conventional medications metformin (MET) and glimepiride (GLI). Lipid profiles were measured, and the data were analyzed using one-way ANOVA, followed by the Tukey-Kramer post-hoc test. Results The study revealed that both BA and WS showed statistically significant lipid-lowering effects in diabetic rats. The BA-treated groups displayed a statistically significant and considerable decrease in total cholesterol (TC) and low-density lipoprotein (LDL) levels compared to the DC group. Similarly, WS-treated groups also showed statistically significant reduced levels of TC and LDL, along with an increase in high-density lipoprotein (HDL). The PHCof BA and WS exhibited enhanced lipid-lowering effects compared to individual treatments. No significant differences in triglyceride (TG) levels were observed among the treatment groups. Conclusion BA and WS, individually and in combination,effectively modulate lipid profiles in T2DM rats. Their synergistic effects provide a promising alternative for managing dyslipidemia in diabetic patients. Further research is needed to determine the clinical consequences of these findings.

Chemical speciation of methylmercury and mercury(II) cations in fish by new fluorogenic naphthalimide alkynyl gold complexes: The ultimate test for detecting fish contamination

The proof of concept of a new portable protocol for the detection and speciation of methylmercury and mercury(II) cations in fish samples is described. In this way, traces of methylmercury and/or mercury(II) cations in fish were quantitatively detected using an elaborated protocol and including a fluorescent sensor. In-the-field accurate results were obtained due to the selective behavior of the chemical sensor in the presence of both cations, working at very low concentrations of mercury species in fish under standard laboratory conditions, that are suitable for daily use in ordinary sampling by border companies importing fish or remote laboratories where large devices cannot be carried. The reported fish protocol is useful under real-life conditions for analyzing fish for the presence of methylmercury in contrast to total mercury analysis. The combination of the protocol and the fluorescent reporter constitutes the ultimate test for fish contamination by mercury(II) species in the workplace. The reported limits of detection of 0.72 nM for Hg2+ and 1.62 nM for CH3Hg+ and the closely related values of the two mercury(II) species in fish samples, obtained by ICP-MS analysis and fluorescent measurements, make the method suitable for daily control of methylmercury in fish under the EU legislation parameters and the WHO recommendations.

Sand fly blood meal volumes and their relation to female body weight under experimental conditions

BackgroundSand fly females require a blood meal to develop eggs. The size of the blood meal is crucial for fecundity and affects the dose of pathogens acquired by females when feeding on infected hosts or during experimental membrane-feeding.MethodsUnder standard laboratory conditions, we compared blood meal volumes taken by females of ten sand fly species from four genera: Phlebotomus, Lutzomyia, Migonomyia, and Sergentomyia. The amount of ingested blood was determined using a haemoglobin assay. Additionally, we weighed unfed sand flies to calculate the ratio between body weight and blood meal weight.ResultsThe mean blood meal volume ingested by sand fly females ranged from 0.47 to 1.01 µl. Five species, Phlebotomus papatasi, P. duboscqi, Lutzomyia longipalpis, Sergentomyia minuta, and S. schwetzi, consumed about double the blood meal size compared to Migonomyia migonei. The mean body weight of females ranged from 0.183 mg in S. minuta to 0.369 mg in P. duboscqi. In males, the mean body weight ranged from 0.106 mg in M. migonei to 0.242 mg in P. duboscqi. Males were always lighter than females, with the male-to-female weight ratio ranging from 75% (in Phlebotomus argentipes) to 52% (in Phlebotomus tobbi).ConclusionsFemales of most species took a blood meal 2.25–3.05 times their body weight. Notably, the relatively tiny females of P. argentipes consumed blood meals 3.34 times their body weight. The highest (Mbl/Mf) ratios were found in both Sergentomyia species studied; females of S. minuta and S. schwetzi took blood meals 4.5–5 times their body weight. This parameter is substantially higher than that reported for mosquitoes and biting midges.Graphical

The Freshwater Cyanobacterium Synechococcus elongatus PCC 7942 Does Not Require an Active External Carbonic Anhydrase.

Under standard laboratory conditions, Synechococcus elongatus PCC 7942 lacks EcaASyn, a periplasmic carbonic anhydrase (CA). In this study, a S. elongatus transformant was created that expressed the homologous EcaACya from Cyanothece sp. ATCC 51142. This additional external CA had no discernible effect on the adaptive responses and physiology of cells exposed to changes similar to those found in S. elongatus natural habitats, such as fluctuating CO2 and HCO3- concentrations and ratios, oxidative or light stress, and high CO2. The transformant had a disadvantage over wild-type cells under certain conditions (Na+ depletion, a reduction in CO2). S. elongatus cells lacked their own EcaASyn in all experimental conditions. The results suggest the presence in S. elongatus of mechanisms that limit the appearance of EcaASyn in the periplasm. For the first time, we offer data on the expression pattern of CCM-associated genes during S. elongatus adaptation to CO2 replacement with HCO3-, as well as cell transfer to high CO2 levels (up to 100%). An increase in CO2 concentration coincides with the suppression of the NDH-14 system, which was previously thought to function constitutively.

Environmental enrichment reduces restricted repetitive behavior by altering gray matter microstructure.

Restricted, repetitive behaviors are common symptoms in neurodevelopmental disorders including autism spectrum disorder. Despite being associated with poor developmental outcomes, repetitive behaviors remain poorly understood and have limited treatment options. Environmental enrichment attenuates the development of repetitive behaviors, but the exact mechanisms remain obscure. Using the C58 mouse model of repetitive behavior, we performed diffusion tensor imaging to examine microstructural alterations associated with the development of repetitive behavior and its attenuation by environmental enrichment. The C57BL/6 mouse strain, which displays little or no repetitive behavior, was used as a control group. We observed widespread differences in diffusion metrics between C58 mice and C57BL/6 mice. In juvenile C58 mice, repetitive motor behavior displayed strong negative correlations with fractional anisotropy in multiple gray matter regions, whereas in young adult C58 mice, high repetitive motor behavior was most strongly associated with lower fractional anisotropy and higher radial diffusivity in the striatum. Environmental enrichment increased fractional anisotropy and axial diffusivity throughout gray matter regions in the brains of juvenile C58 mice and overlapped predominantly with cerebellar and sensory regions associated with repetitive behavior. Our results suggest environmental enrichment reduces repetitive behavior development by altering gray matter microstructure in the cerebellum, medial entorhinal cortex, and sensory processing regions in juvenile C58 mice. Under standard laboratory conditions, early pathology in these regions appears to contribute to later striatal and white matter dysfunction in adult C58 mice. Future studies should examine the role these regions play in the development of repetitive behavior and the relationship between sensory processing and cerebellar deficits and repetitive behavior.

FGF1

Fibroblast Growth Factor 1 (Fgf1), also known as acidic FGF (aFGF), is involved in the regulation of various biological processes, ranging from development to disease pathogenesis. It is a single chain polypeptide and is highly expressed in adult brain and kidney tissues. Its expression has been shown to be directed by multiple tissue-specific promoters, which generate transcripts of varying lengths. During development the Fgf1 gene is widely expressed, including in the neural tube, heart and lung. Mouse mutants for this gene are normal under standard laboratory conditions. However, when Fgf1 mutants are exposed to a high fat diet, an aggressive diabetic phenotype has been reported, along with aberrant adipose tissue expansion. Ongoing research on FGF1 and its signalling pathways holds promise for greater understanding of developmental processes as well as the development of novel therapeutic interventions for diseases including diabetes.

Substantial contribution of inorganic carbon sources to CO2 emissions in calcareous vineyard soils in Germany

AbstractIn light of climate change and increasing global temperatures, it is important to equally prioritize the study of inorganic carbon dynamics in calcareous soils within temperate ecosystems, as has been done for arid or semiarid environments. A significant area of vineyards in Germany is established on calcareous soils. However, the potential influence of inorganic carbon on CO2 emissions in these vineyards has not been sufficiently explored when evaluating the carbon footprint of management practices in relation to carbon storage. Therefore, we aimed to differentiate between organic and inorganic sources of CO2 emissions from six vineyard soils located in the southwest of Germany that had previously received organic soil amendments (OA). Inorganic carbon content varied between 8 and 55 g kg−1 across different sites, with variations observed in the inorganic‐to‐organic carbon ratio. Soil samples were incubated under standard laboratory conditions for 48 h, and the source of emitted CO2 was determined using a two‐end‐member mixing model. The contribution of inorganic carbon to CO2 emissions was influenced by the quantity of inorganic carbon, with an increase in contribution with increasing inorganic‐to‐organic carbon ratio. On average, abiotic sources accounted for 5% to 40% of the emitted CO2 at the different sites, with one site showing no significant contribution of inorganic carbon. CO2 production from inorganic carbon was higher in the subsoil compared with the topsoil, likely related to the higher content of inorganic carbon in the subsoil. Notably, there was no discernible influence of OA on carbonate dissolution. This study emphasizes the significance of considering abiotic sources of CO2 emissions in addition to soil respiration in calcareous soils and highlights the need for further investigation to apply these findings at the field scale.

Effects of Aloe Vera Gel on Red Blood Cell-parameters in Phenylhydrazine-induced Anaemic Wistar albino Rats

Background & objective: Anaemia is the most significant disorder of the blood. Many researchers have developed the concept of using medicinal plants as an alternative source of treatment for anaemia with fewer side effects. Aloe vera, being a medicinal plant, is popularly used as a natural drug in haematological disorders. The present study was intended to observe the effects of Aloe vera gel on red blood cell parameters in phenylhydrazine (PHZ)-induced anaemic Wistar albino rats. Methods: This Experimental study was conducted in Dhaka Medical College, Dhaka from July 2021 to June 2022. A total of 24 healthy Wistar albino rats were selected for the study. After procurement, the rats were initially kept in a standard laboratory condition on a 12/12-hour light/dark cycle for 14 days of acclimatization before 21 days of the experiment. All the rats had free access to basal diet and normal saline during the period of acclimatization and experiment. After acclimatization for 14 days, the rats were divided into three groups-Group A (baseline control group, n = 8), Group B (PHZ-treated group, n = 8), and Group C, the Experimental Group (PHZ-induced and Aloe vera gel treated group, n = 8). To induce anaemia, Group B and Group C received intraperitoneal injection of PHZ at a dose of 0.5 ml/100 g body weight on days 1, 3, 5 and day 7. Moreover, the experimental group (Group C) received Aloe vera gel orally at a dose of 0.6 ml/kg body weight from Day 8 to Day 21. On day 22, rats were sacrificed to test their blood samples for haematologic variables (RBC count, Hb conc., and PCV) and haematological indices (MCV, MCH and MCHC). Result: All the haematological parameters and indices were almost similar among the study groups at baseline (on Day 1). On Day 8, rats of groups B and C demonstrated a drastically reduced count of RBC (2.66 ± 0.53 and 2.69 ± 0.52 million/μl respectively) compared to the rats of group A (8.16 ± 0.76 million/μl). On Day 22, the RBC count in rats of Group C staggeringly increased to 7.63 ± 0.64 million/μl; however, the RBC count in rats of Group B remained almost the same as was found on Day 8. A significant decrease in Hb conc. and PCV in PHZ-induced control on Day 8 compared to that on Day 1 was also observed. The mean MCV in all the study groups on Day 1 was around 50 fl, which abnormally increased to 85 and 87 fl in Groups B and C respectively on Day 8. On Day 22, Group B further exhibited an increase in MCV to > 87 fl. Meanwhile, the MCV in Group C (Aloe vera-treated group) favourably decreased to 55 fl. On the 8th Day of intervention, the MCH level significantly decreased in Groups B and C. Although no significant change in MCH was observed in Group B from Day 8 to Day 22, group C demonstrated a significant increase in the mean MCH to nearly 18 pg during the same period. The mean MCHC significantly dropped to < 23% in Groups B and C on Day 8 from the baseline figure of 34%. While no significant change in MCHC was evident in Group B from Day 8 to Day 22, it significantly improved to about 28% in Group C during the same period. Conclusion: From the study, it can be concluded that Aloe vera has significant erythropoietic potentials which result in the improvement of red blood cell parameters (RBC count, Hb conc., PCV, MCV, MCH and MCHC) in PHZ-induced anaemic rats. Ibrahim Card Med J 2023; 13 (1&2): 40-46

Metabolome and Genome Analysis of a Novel Endophytic Fungus Aureobasidium pullulans KB3: Discovery of Polyketones and Polyketone Biosynthesis Pathway.

Endophytic fungi associated with plants may contain undiscovered bioactive compounds. Under standard laboratory conditions, most undiscovered compounds are inactive, whereas their production could be stimulated under different cultivation conditions. In this study, six endophytic fungi were isolated from the bark of Koelreuteria paniculata in Quancheng Park, Jinan City, Shandong Province, one of which was identified as a new subspecies of Aureobasidium pullulans, named A. pullulans KB3. Additionally, metabolomic tools were used to screen suitable media for A. pullulans KB3 fermentation, and the results showed that peptone dextrose medium (PDM) was more beneficial to culture A. pullulans KB3 for isolation of novel compounds. Sphaerolone, a polyketone compound, was initially isolated from A. pullulans KB3 via scaled up fermentation utilizing PDM. Additionally, the whole-genome DNA of A. pullulans KB3 was sequenced to facilitate compound isolation and identify the biosynthesis gene clusters (BGCs). This study reports the multi-omics (metabolome and genome) analysis of A. pullulans KB3, laying the foundation for discovering novel compounds of silent BGCs and identifying their biosynthesis pathway.

The role of defects in high-silica zeolite hydrolysis and framework healing

The stability of high silica zeolites under standard laboratory and mild steaming conditions is understood to be due to the lack of hydrophilic Al-O-Si moieties, which can be targeted by water via hydrolysis reactions with relatively low barriers. However, in hydrophobic high-silica and siliceous frameworks, the specific interactions between water and the internal framework sites are incompletely understood. In particular, the behaviour of common internal defects, including partial hydrolysis species and silanol nests are not established, despite their expected role in accelerating the decomposition of the framework. In this work, we utilise machine learning potentials combined with density functional calculations to rigorously sample the hydrolysis processes in siliceous zeolites with topologies CHA and MFI under low water conditions and quantify the effect of defects. Internal silanol defect sites are found to accelerate zeolite decomposition primarily by bypassing the initial, high-barrier hydrolysis step. Subsequent steps proceed with lower reaction barriers. However, all reaction steps are found to be highly activated, and unlikely to occur rapidly at room temperature under conditions of low internal water concentration. Exchange-healing routes, which reverse hydrolysis while incorporating oxygen from water molecules are found to be competitive along the entire hydrolysis pathway in CHA, providing an additional source of stabilization against hydrolytic decomposition.

Malic enzyme 1 knockout has no deleterious phenotype and is favored in the male germline under standard laboratory conditions.

Malic Enzyme 1 (ME1) plays an integral role in fatty acid synthesis and cellular energetics through its production of NADPH and pyruvate. As such, it has been identified as a gene of interest in obesity, type 2 diabetes, and an array of epithelial cancers, with most work being performed in vitro. The current standard model for ME1 loss in vivo is the spontaneous Mod-1 null allele, which produces a canonically inactive form of ME1. Herein, we describe two new genetically engineered mouse models exhibiting ME1 loss at dynamic timepoints. Using murine embryonic stem cells and Flp/FRT and Cre/loxP class switch recombination, we established a germline Me1 knockout model (Me1 KO) and an inducible conditional knockout model (Me1 cKO), activated upon tamoxifen treatment in adulthood. Collectively, neither the Me1 KO nor Me1 cKO models exhibited deleterious phenotype under standard laboratory conditions. Knockout of ME1 was validated by immunohistochemistry and genotype confirmed by PCR. Transmission patterns favor Me1 loss in Me1 KO mice when maternally transmitted to male progeny. Hematological examination of these models through complete blood count and serum chemistry panels revealed no discrepancy with their wild-type counterparts. Orthotopic pancreatic tumors in Me1 cKO mice grow similarly to Me1 expressing mice. Similarly, no behavioral phenotype was observed in Me1 cKO mice when aged for 52 weeks. Histological analysis of several tissues revealed no pathological phenotype. These models provide a more modern approach to ME1 knockout in vivo while opening the door for further study into the role of ME1 loss under more biologically relevant, stressful conditions.

Assessment of Tooth Shade Measurement Precision and Consistency with Digital Photography Calibration System.

To ascertain the degree of precision and repeatability inherent in the "capture to edit" digital imaging system, namely the ColorChecker Passport Photo (X-Rite, MI, USA), and to juxtapose its performance against spectrophotometric assessments utilizing the Vita Easyshade® (Vita Zahnfabrik, H Rauter GmbH & Co. KG., Bad Sackingen, Germany) for the same set of teeth. Eighty participants aged 19-25 were included in the study; all of them were Croatian students at the School of Dental Medicine, University of Zagreb. Color measurements of the maxillary right central incisors were performed in controlled, standardized laboratory conditions. The measurements were performed on calibrated digital photographs by an experienced clinician three times in a row, and L, a, and b of CIELAB color space values were recorded. The same procedure was performed using the Vita Easyshade 5.0 spectrophotometer (Vita Zahnfabrik, Bad Säckingen, Germany) in "Tooth single" mode. The Cronbach's alpha was used as a repeatability measurement, thus revealing high consistency for both methods (α=0.94-1). Correlations were moderate (Pearson r=0.44-0.66 p<0.05). Testing confirmed that digital photography is inaccurate as spectrophotometry (p<0.05). An analysis of errors of means and their standard deviations revealed consistent discrepancies with minor deviations. The "capture to edit" method showed high consistency (Cronbach's α=0.94-0.96), and it exhibits comparability in terms of variability, reliability, and repeatability when compared to spectrophotometric measurement (VitaShade 5, VitaZahnfabrik). Disparities between the methods are evident and anticipated, yet they do not follow a consistently linear pattern. The combination of repeatability and consistency renders the "capture to edit" method a valuable tool for enhanced color mapping, thus facilitating comparisons between digital images.

Discovery, characterization, and engineering of an advantageous Streptomyces host for heterologous expression of natural product biosynthetic gene clusters

BackgroundStreptomyces is renowned for its robust biosynthetic capacity in producing medically relevant natural products. However, the majority of natural products biosynthetic gene clusters (BGCs) either yield low amounts of natural products or remain cryptic under standard laboratory conditions. Various heterologous production hosts have been engineered to address these challenges, and yet the successful activation of BGCs has still been limited. In our search for a valuable addition to the heterologous host panel, we identified the strain Streptomyces sp. A4420, which exhibited rapid initial growth and a high metabolic capacity, prompting further exploration of its potential.ResultsWe engineered a polyketide-focused chassis strain based on Streptomyces sp. A4420 (CH strain) by deleting 9 native polyketide BGCs. The resulting metabolically simplified organism exhibited consistent sporulation and growth, surpassing the performance of most existing Streptomyces based chassis strains in standard liquid growth media. Four distinct polyketide BGCs were chosen and expressed in various heterologous hosts, including the Streptomyces sp. A4420 wild-type and CH strains, alongside Streptomyces coelicolor M1152, Streptomyces lividans TK24, Streptomyces albus J1074, and Streptomyces venezuelae NRRL B-65442. Remarkably, only the Streptomyces sp. A4420 CH strain demonstrated the capability to produce all metabolites under every condition outperforming its parental strain and other tested organisms. To enhance visualization and comparison of the tested strains, we developed a matrix-like analysis involving 15 parameters. This comprehensive analysis unequivocally illustrated the significant potential of the new strain to become a popular heterologous host.ConclusionOur engineered Streptomyces sp. A4420 CH strain exhibits promising attributes for the heterologous expression of natural products with a focus on polyketides, offering an alternative choice in the arsenal of heterologous production strains. As genomics and cloning strategies progress, establishment of a diverse panel of heterologous production hosts will be crucial for expediting the discovery and production of medically relevant natural products derived from Streptomyces.

Right ventricular pacing-evoked left ventricular dysfunction is exaggerated by sustained left ventricular pressure overload in a rat model

Abstract Introduction A growing body of evidence suggests that in the presence of left bundle branch block-induced electromechanical dyssynchrony, the function of the left ventricle (LV) becomes extremely sensitive to arterial afterload. However, data is scarce whether right ventricular pacing (RVP) also sensitizes the LV to alterations in afterload. Purpose Hence, in the present translational study we aimed to characterize the acute effect of RVP on LV hemodynamics under standard laboratory conditions using a rat model of chronic LV pressure overload (PO). Methods Transverse aortic constriction (TAC group) was carried out in male Wistar rats to evoke sustained LV PO for six weeks. Age- and sex-matched sham-operated animals served as controls (Sham group). LV hemodynamics was assessed in anesthetized rats by pressure-volume analysis using a pressure-conductance micro-catheter (SPR-838) introduced to the LV via the right carotid artery. To evoke RVP, the right jugular vein was cannulated and an ultra-miniature octopolar electrophysiology catheter (EPR-800) was placed into the right ventricle. Pressure-volume loops were registered in the TAC and the Sham groups during intrinsic narrow QRS rhythm (termed as TAC-Vsense and Sham-Vsense) as well as during RVP (termed as TAC-Vpace and Sham-Vpace). Results RVP was associated with impaired diastolic function (active relaxation time constant [τ]: 8.6±0.3 vs. 9.6±0.3ms, Sham-Vsense vs. Sham-Vpace and 8.0±0.3 vs. 9.6±0.4ms, TAC-Vsense vs. TAC-Vpace; P&amp;lt;0.001 for both comparisons) and decreased LV contractility (preload recruitable stroke work [PRSW]: 139±9 vs. 114±9mmHg, Sham-Vsense vs. Sham-Vpace and 255±23 vs. 169±17mmHg, TAC-Vsense vs. TAC-Vpace; P&amp;lt;0.001 for both comparisons) in both the TAC and the Sham groups. Nevertheless, the extent of RVP-evoked active relaxation prolongation (Δτ: 12±2 vs. 20±2%, Sham vs. TAC, P=0.005) and LV contractility reduction (ΔPRSW: -18±4 vs. -34±3%, Sham vs. TAC, P=0.007) was found to be more robust in rats with sustained LV PO compared to controls. Conclusion Our experimental results indicate that RVP-induced LV dysfunction is exaggerated in case of sustained LV PO.