The Iroquois (Iro/Irx) homeobox genes are conserved Hox targets involved in motor neuron development.

The Iroquois (Iro/Irx) homeobox genes encode transcription factors with fundamental roles in animal development. Despite their link to various congenital conditions in humans, our understanding of Iro/Irx gene expression, function, and regulation remains incomplete. Here, we conducted a systematic expression analysis of all six mouse Irx genes in the embryonic spinal cord. We found five Irx genes (Irx1, Irx2, Irx3, Irx5, and Irx6) to be confined mostly to ventral spinal domains, offering new molecular markers for specific groups of post-mitotic motor neurons (MNs). Further, we engineered Irx2, Irx5, and Irx6 mouse mutants and uncovered essential but distinct roles for Irx2 and Irx6 in MN development. Last, we found that the highly conserved regulators of MN development across species, the HOX proteins, directly control Irx gene expression both in mouse and C. elegans MNs, critically expanding the repertoire of HOX target genes in the developing nervous system. Altogether, our study provides important insights into Iro/Irx expression and function in the developing spinal cord, and uncovers an ancient gene regulatory relationship between HOX and Iro/Irx genes.

Soil amendments reduce CH4 and CO2 but increase N2O and NH3 emissions in saline-alkali paddy fields.

Limited research has been conducted on ammonia (NH3) volatilization and greenhouse gases (GHGs) emissions in saline-alkali paddy fields, along with complex interaction involving various genes (16sRNA, amoA, narG, nirK, nosZ, and nifH). This study employed mesocosm-scale experiment to investigate NH3 volatilization and GHGs emissions, focusing on bacterial communities and genic abundance, in saline-alkali paddy fields with desulfurized gypsum (DG) and organic fertilizer (OF) amendments. Compared to the control (CK) treatment, DG and OF treatments reduced methane (CH4) and carbon dioxide (CO2) emissions by 78.05 % and 26.18 %, and 65.84 % and 11.62 %, respectively. However, these treatments increased NH3 volatilization by 26.26 % and 45.23 %, and nitrous oxide (N2O) emission by 41.00 % and 12.31 %. Notably, NH3 volatilization primarily stemmed from ammonia nitrogen (NH4+-N), rather than total nitrogen (TN) in soil and water. N2O was mainly produced from nitrate nitrogen (NO3--N) in soil and water, as well as NH4+-N in water. The increase in NH3 volatilization and N2O emission in DG and OF treatments, was attributed to the reduced competition among bacterial communities, rather than the increased bacterial activity and genic copies. These findings offer valuable insights for managing nutrient loss and gaseous emissions in saline-alkali paddy fields.

Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species.

Constructed wetlands (CWs) are pivotal for wastewater treatment due to their high efficiency and numerous advantages. The impact of plant species and diversity on greenhouse gas (GHG) emissions from CWs requires a more comprehensive evaluation. Moreover, controversial perspectives persist about whether CWs function as carbon sinks or sources. In this study, horizontal subsurface flow (HSSF) CWs vegetated with Cyperus alternifolius, Typhae latifolia, Acorus calamus, and the mixture of these three species were constructed to evaluate pollutant removal efficiencies and GHG emissions, and estimate carbon budgets. Polyculture CWs can stably remove COD (86.79 %), NH4+-N (97.41 %), NO3--N (98.55 %), and TP (98.48 %). They also mitigated global warming potential (GWP) by suppressing N2O emissions compared with monoculture CWs. The highest abundance of the Pseudogulbenkiania genus, crucial for denitrification, was observed in polyculture CWs, indicating that denitrification dominated in nitrogen removal. While the highest nosZ copy numbers were observed in CWs vegetated with Cyperus alternifolius, suggesting its facilitation of denitrification-related microbes. Selecting Cyperus alternifolius to increase species diversity is proposed for simultaneously maintaining the water purification capacity and reducing GHG emissions. Carbon budget estimations revealed that all four types of HSSF CWs were carbon sinks after six months of operation, with carbon accumulation capacity of 4.90 ± 1.50 (Cyperus alternifolius), 3.31 ± 2.01 (Typhae latifola), 1.78 ± 1.30 (Acorus calamus), and 2.12 ± 0.88 (polyculture) kg C/m2/yr. This study implies that under these operation conditions, CWs function as carbon sinks rather than sources, aligning with carbon peak and neutrality objectives and presenting significant potential for carbon reduction efforts.

Association of serum uric acid with male sexual hormones and erectile dysfunction: a bidirectional 2-sample Mendelian randomization analysis.

Background: Observational studies indicated that serum uric acid (SUA) was associated with male sexual hormones and erectile dysfunction (ED). However, their relationship was still heterogeneous. Aim: This study conducted 2-sample univariate mendelian randomization (UVMR) and multivariate mendelian randomization (MVMR) to explore the causal relationship between SUA and sexual hormones as well as ED. Methods: Genetic variants associated with SUA were derived from the UK Biobank database (N = 437 354). Outcomes from the IEU Open GWAS and summary data sets were sexual hormones (sex hormone-binding globulin [SHBG], testosterone, estradiol [E2], follicle-stimulating hormone, luteinizing hormone) and ED, with 3301 to 625 650 participants. UVMR analysis primarily utilized the inverse variance weighted method, complemented by MVMR analysis. Thorough sensitivity analyses were carried out to ensure the reliability of results. Moreover, mediation analysis was conducted to estimate the mediated effect between SUA and outcomes. Outcomes: The primary outcomes included results of UVMR and MVMR analysis and mediation analysis, along with sensitivity analyses involving the Cochran Q test, the MR Egger intercept test, leave-1-out analysis, and the MR-PRESSO method (mendelian randomization pleiotropy residual sum and outlier). Results: UVMR analysis revealed that an elevated SUA level could decrease levels of SHBG (ß = -0.10, P = 1.70 × 10-7) and testosterone (ß = -0.10, P = 5.94 × 10-3) and had a positive causal effect on ED (odds ratio, 1.10; P = .018). According to reverse mendelian randomization results, increased levels of SHBG (ß = -0.06, P = 4.82 × 10-4) and E2 (ß = -0.04, P = .037) could also reduce SUA levels. As shown by MVMR analysis, SUA had a negative effect on SHBG and testosterone levels (P < .05), while the significant causal relationship between SUA and ED disappeared. Furthermore, SHBG mediated 98.1% of the effect of SUA on testosterone levels. Results of other mendelian randomization analyses were not statistically significant. No pleiotropy was found by sensitivity analysis in this study. Clinical Implications: Given the causal relationship between SUA and sexual hormones, we must focus on SUA and E2 levels in men, especially patients with hypogonadism and ED. Strengths and Limitations: This study evaluated the causal effect of SUA on male sexual hormones and ED genetically for the first time, clarifying the common biases in observational studies and confirming the negative relationship between SUA and testosterone level. Limitations include a population based on European ancestry, some crossover of the samples, and unobserved confounding factors. Conclusion: Genetic studies provide evidence for the causal relationship between SUA and male sexual hormones (SHBG, testosterone, E2), while the relationship between SUA and ED should be further evaluated.

A molecular atlas of adult C. elegans motor neurons reveals ancient diversity delineated by conserved transcription factor codes.

Motor neurons (MNs) constitute an ancient cell type targeted by multiple adult-onset diseases. It is therefore important to define the molecular makeup of adult MNs in animal models and extract organizing principles. Here, we generate a comprehensive molecular atlas of adult Caenorhabditis elegans MNs and a searchable database. Single-cell RNA sequencing of 13,200 cells reveals that ventral nerve cord MNs cluster into 29 molecularly distinct subclasses. Extending C. elegans Neuronal Gene Expression Map and Network (CeNGEN) findings, all MN subclasses are delineated by distinct expression codes of either neuropeptide or transcription factor gene families. Strikingly, combinatorial codes of homeodomain transcription factor genes succinctly delineate adult MN diversity in both C. elegans and mice. Further, molecularly defined MN subclasses in C. elegans display distinct patterns of connectivity. Hence, our study couples the connectivity map of the C. elegans motor circuit with a molecular atlas of its constituent MNs and uncovers organizing principles and conserved molecular codes of adult MN diversity.