Explore the vast range of titles available.

Diversity-generating retroelements (DGRs) create massive protein sequence variation (up to 10 30 ) 1 in ecologically diverse microorganisms. A recent survey identified around 31,000 DGRs from more than 1,500 bacterial and archaeal genera, constituting more than 90 environment types 2 . DGRs are especially enriched in the human gut microbiome 2 , 3 and nano-sized microorganisms that seem to comprise most microbial life and maintain DGRs despite reduced genomes 4 , 5 . DGRs are also implicated in the emergence of multicellularity 6 , 7 . Variation occurs during reverse transcription of a protein-encoding RNA template coupled to misincorporation at adenosines. In the prototypical Bordetella bacteriophage DGR, the template must be surrounded by upstream and downstream RNA segments for complementary DNA synthesis to be carried out by a complex of the DGR reverse transcriptase bRT and associated protein Avd. The function of the surrounding RNA was unknown. Here we show through cryogenic electron microscopy that this RNA envelops bRT and lies over the barrel-shaped Avd, forming an intimate ribonucleoprotein. An abundance of essential interactions in the ribonucleoprotein precisely position an RNA homoduplex in the bRT active site for initiation of reverse transcription. Our results explain how the surrounding RNA primes complementary DNA synthesis, promotes processivity, terminates polymerization and strictly limits mutagenesis to specific proteins through mechanisms that are probably conserved in DGRs belonging to distant taxa. This study presents cryogenic electron microscopy structural analysis of a diversity-generating retroelement (DGR) reverse transcription system from Bordetella bacteriophage, with results indicating that RNA surrounding the template controls reverse transcription through mechanisms that are conserved across distant taxa.

A heterogeneous photocatalyst amenable to catalyze different chemical reactions is a highly enabling and sustainable material for organic synthesis. Herein we report the synthesis and characterization of an azobenzene-based organic π–conjugated porous polymer (AzoCPP) as heterogeneous dual photocatalyst manifesting net-oxidative bromination of arenes and dehydroxylation of boronic acids to corresponding phenols. Hierarchical porosity and high surface area of the nano-sized AzoCPP allowed superior catalyst-substrate contact during catalyses, whereas the inherent structural defect present in the CPP backbone resulted in low-energy sinks functioning as de facto catalytic sites. A combination of these two structure-property aspects of AzoCPP, in addition to the dielectric constant manipulation of the system, led to excellent catalytic performance. The protocols remained valid for a wide substrate scope and the catalyst was recycled multiple times without substantial loss in catalytic activity. With the aid of subsequent control experiments and analytical characterizations, mechanisms for each catalysis are proposed and duly corroborated.

Diversity-generating retroelements (DGRs) create massive protein sequence variation in ecologically diverse microbes. Variation occurs during reverse transcription of a protein-encoding RNA template coupled to misincorporation at adenosines. In the prototypical bacteriophage DGR, the template must be surrounded by upstream and downstream RNA segments for cDNA synthesis by the reverse transcriptase bRT and associated protein Avd. The function of the surrounding RNA was unknown. Cryo-EM revealed that this RNA enveloped bRT and lay over barrel-shaped Avd, forming an intimate ribonucleoprotein (RNP). An abundance of essential interactions between RNA structural elements and bRT-Avd precisely positioned an RNA homoduplex for initiation of cDNA synthesis by -priming. Our results explain how the surrounding RNA primes cDNA synthesis, promotes processivity, terminates polymerization, and strictly limits mutagenesis to select proteins through mechanisms that are likely conserved in DGRs from distant taxa.

Recommender systems have become a core component of digital platforms, enabling personalized content delivery and enhancing user engagement across industries such as e-commerce, entertainment, and social networking. This study presents a comparative evaluation of collaborative filtering (CF) algorithms, including User-Based CF, Item-Based CF, Singular Value Decomposition (SVD), Non-negative Matrix Factorization (NMF), and a Hybrid CF model that integrates both memory-based and model-based approaches. Using the MovieLens 1M and Amazon Product Review datasets, the algorithms were assessed across multiple performance dimensions; predictive accuracy (RMSE, MAE), ranking quality (Precision@10, Recall@10, F1-score), and computational efficiency (training time, scalability, and memory usage). The results revealed that the Hybrid CF model achieved the highest overall performance, with the lowest RMSE (0.811) and the highest F1-score (0.731), outperforming traditional CF methods by over 13% in accuracy and 11% in ranking metrics. Although it required slightly higher computational resources, the Hybrid CF model demonstrated superior scalability and adaptability in both sparse and dense data environments. Cluster analysis further confirmed a clear distinction between memory-based and model-based methods, with the Hybrid CF forming an independent sub-cluster due to its unique performance balance. The findings conclude that hybrid collaborative filtering represents the most effective and future-ready solution for modern recommender systems, offering an optimal blend of accuracy, efficiency, and scalability for large-scale, data-intensive applications.

Moisture flux and precipitable water content (PWC) analysis are carried out over Himalayan state of Uttarakhand, India during the Indian summer monsoon season for the period 1959–2021 (1959–2001: P1; 2002–2021: P2) to understand their distribution pattern. The intense moisture convergence is seen over the hilly region in the recent past (P2) through the rotational and divergent components of moisture flux analysis. The analysis indicates an increasing trend of PWC with values 1.2, 1.9, 2.0 and 2.5 mm/decade during June to September months respectively. The spatial distribution of rainfall shows a stronger magnitude in the eastern part and relatively weaker magnitude in the western part, during June to August since 2002. Convective available potential energy (CAPE) is increased in the low altitude region in the summer months except July and shows maximum during September (~ 100 J/kg) since 2002. However, the study of vertically integrated moisture flux divergence (VIMFD) shows stronger (weaker) convergence in the windward side (leeward side) in Uttarakhand. These climatological distributions of PWC, CAPE, rainfall, and VIMFD analysis implicate a signature of cloud burst/heavy precipitation region in the recent past in Uttarakhand.

The intensity of Tropical Easterly Jet (TEJ) is profoundly associated with the Indian Summer monsoon rainfall (ISMR). Epochal analysis of the TEJ intensity has been carried out by dividing the period of 1976–2021 into two equal epochs, E1 (1976–1998) and E2 (1999–2021), with a breaking point corresponding to the 1998/99 climate shift. Further, the evolution of the relationship between ISMR and the intensity of TEJ across the two epochs has also been studied using Mann–Kendall (MK) trend analysis and Innovative trend analysis (ITA) techniques. Diabatic heating over the Tibetan anticyclonic and TEJ regions is also analyzed to study epochal variability. The relationship dynamics are further explored using multivariate correlation analysis of ISMR with the TEJ intensity, meridional temperature gradients (at 150 hPa and 200 hPa), air temperature anomaly index, and outgoing longwave radiation (OLR). The study indicates the reversal or stabilizing of the significant declining trend in the meridional upper-level tropospheric temperature gradient in E2, specifically at 150 and 200 hPa. OLR shows a declining trend of 0.12 Wm −2  yr −1 in E2 with a 90% confidence level, whereas with an insignificant decreasing trend of 0.06 Wm −2  yr −1 in E1. An increment in diabatic heating (Q1) and a regime shift is observed in the Tibetan anticyclonic (TP) region in E2 compared to E1. TEJ intensity increased with a confidence level above 90% at 150 hPa (0.04 ms −1  yr −1 ) and 200 hPa (0.06 ms −1  yr −1 .). Longitudinal oscillation in the position of the TEJ core is also observed; specifically, regime shift in the longitudinal position of the TEJ core is observed in E2 compared to E1. Multivariate correlation analysis of TEJ intensity at 150 and 200 hPa; meridional temperature gradient between TEJ and TP region at 150 and 200 hPa; OLR with ISMR indicate increased correlation of tropospheric temperature gradients at 150 and 200 hPa with OLR and ISMR. A marginal increase of 0.05 in the correlation coefficient between TEJ intensity and ISMR is also reported at 150 hPa.

Arsenic, a surreptitious presence in our environment, perpetuates a persistent global menace with its deleterious impacts. It possesses the capability to trigger substantial immunosuppression by instigating inflammation in critical organs like the thymus and spleen. L-Ascorbic acid (L-AA) exhibits robust immunoregulatory prowess by orchestrating the epigenetic terrain through TET and JHDM pathways. Conversely, α-tocopherol (α-T) demonstrates the capacity to dampen the production of pro-inflammatory cytokines by modulating the PI3K-Akt axis. Given these insights, this inquiry embarks on exploring the mitigative potential of L-AA and α-T co-supplementation at the transcriptome level within leukocytes under arsenic exposure. Concurrently, the research endeavours to unravel the potent anti-inflammatory effects of administering α-T and L-AA, alleviating inflammation within the spleen and thymus amidst arsenic-induced insult and delving deeply into their immunomodulatory mechanisms. The rats were randomly allocated into eight distinct groups for subsequent experimentation: (I) the control group was administered solely with distilled water as the vehicle (control); (II) NaAsO 2 -treated group (As); (III) NaAsO 2 treated along with L-ascorbic acid and α-tocopherol supplemented group (As + L-AA + α-T); (IV) L-ascorbic acid and α-tocopherol supplemented group (L-AA + α-T); (V) NaAsO 2 treated along with L-ascorbic acid supplemented group (As + L-AA); (VI) only L-ascorbic acid supplemented group (L-AA); (VII) NaAsO 2 treated along with α-tocopherol supplemented group (As + α-T); (VIII) only α-tocopherol supplemented group (α-T). Rats treated with NaAsO 2 exhibited an increased neutrophil count in their bloodstream, as revealed by a comprehensive transcriptomic analysis showcasing heightened expressions of ItgaM, MMP9, and Itga4 within circulating leukocytes under arsenic exposure. Concurrently, arsenic heightened the expression of pro-inflammatory cytokines within the thymus and spleen. This elevated cytokine activity promoted the upregulation of ICAM-1 on vascular endothelial cells, facilitating the infiltration of Ly6g + leukocytes into the afflicted thymus and spleen. Remarkably, the combination of L-AA acid and α-T demonstrated substantial therapeutic efficacy, adeptly reducing the influx of Ly6g + leukocytes into these immune sites and subsequent reduction of excessive collagen deposition. The dynamic duo of L-AA and α-T achieved this amelioration by suppressing the expression of ItgaM, MMP9, and Itga4 mRNA within circulating leukocytes and moderating tissue levels of pro-inflammatory cytokines in arsenic-exposed thymus and spleen. Graphical Abstract