Higher Organisms Research Articles

Mercury dynamics at the base of the pelagic food web of the Gulf of Gdańsk, southern Baltic Sea

Planktonic organisms, which have direct contact with water, serve as the entry point for mercury (Hg), into the marine food web, impacting its levels in higher organisms, including fish, mammals, and humans who consume seafood. This study provides insights into the distribution and behavior of Hg within the Baltic Sea, specifically the Gulf of Gdańsk, focusing on pelagic primary producers and consumers. Phytoplankton Hg levels were primarily influenced by its concentrations in water, while Hg concentrations in zooplankton resulted from dietary exposure through suspended particulate matter and phytoplankton consumption. Hg uptake by planktonic organisms, particularly phytoplankton, was highly efficient, with Hg concentrations four orders of magnitude higher than those in the surrounding water. However, unlike biomagnification of Hg between SPM and zooplankton, biomagnification between zooplankton and phytoplankton was not apparent, likely due to the low trophic position and small size of primary consumers, high Hg elimination rates, and limited absorption.

Dnttip2 is essential for 18S rRNA processing and digestive organ development in zebrafish

Dnttip2 is one of the components of the small subunit (SSU) processome. In yeast, depletion of dnttip2 leads to an inefficient processing of pre-rRNA and a decrease in synthesis of the mature 18S rRNA. However, the biological roles of Dnttip2 in higher organisms are poorly defined. In this study, we demonstrate that dnttip2 is a maternal gene in zebrafish. Depletion of Dnttip2 leads to embryonic lethal with severe digestive organs hypoplasia. The loss of function of Dnttip2 also leads to partial defects in cleavage at the A0-site and E-site during 18S rRNA processing. In conclusion, Dnttip2 is essential for 18S rRNA processing and digestive organ development in zebrafish.

Physiological adventures in Candida albicans: farnesol and ubiquinones.

SUMMARYFarnesol was first identified as a quorum-sensing molecule, which blocked the yeast to hyphal transition in Candida albicans, 22 years ago. However, its interactions with Candida biology are surprisingly complex. Exogenous (secreted or supplied) farnesol can also act as a virulence factor during pathogenesis and as a fungicidal agent triggering apoptosis in other competing fungi. Farnesol synthesis is turned off both during anaerobic growth and in opaque cells. Distinctly different cellular responses are observed as exogenous farnesol levels are increased from 0.1 to 100 µM. Reported changes include altered morphology, stress response, pathogenicity, antibiotic sensitivity/resistance, and even cell lysis. Throughout, there has been a dearth of mechanisms associated with these observations, in part due to the absence of accurate measurement of intracellular farnesol levels (Fi). This obstacle has recently been overcome, and the above phenomena can now be viewed in terms of changing Fi levels and the percentage of farnesol secreted. Critically, two aspects of isoprenoid metabolism present in higher organisms are absent in C. albicans and likely in other yeasts. These are pathways for farnesol salvage (converting farnesol to farnesyl pyrophosphate) and farnesylcysteine cleavage, a necessary step in the turnover of farnesylated proteins. Together, these developments suggest a unifying model, whereby high, threshold levels of Fi regulate which target proteins are farnesylated or the extent to which they are farnesylated. Thus, we suggest that the diversity of cellular responses to farnesol reflects the diversity of the proteins that are or are not farnesylated.

Biological activity of silver nanoparticles synthesized using viticultural waste

This research paper presents a novel approach to the green synthesis of silver nanoparticles (AgNPs) using viticultural waste, allowing to obtain NP dispersions with distinct properties and morphologies (monodisperse and polydisperse AgNPs, referred to as mAgNPs and pAgNPs) and to compare their biological activities. Our synthesis method utilized the ethanolic extract of Vitis vinifera pruning residues, resulting in the production of mAgNPs and pAgNPs with average sizes of 12 ± 5 nm and 19 ± 14 nm, respectively. Both these AgNPs preparations demonstrated an exceptional stability in terms of size distribution, which was maintained for one year. Antimicrobial testing revealed that both types of AgNPs inhibited either the growth of planktonic cells or the metabolic activity of biofilm sessile cells in Gram-negative bacteria and yeasts. No comparable activity was found towards Gram-positives. Overall, pAgNPs exhibited a higher antimicrobial efficacy compared to their monodisperse counterparts, suggesting that their size and shape may provide a broader spectrum of interactions with target cells. Both AgNP preparations showed no cytotoxicity towards a human keratinocyte cell line. Furthermore, in vivo tests using a silkworm animal model indicated the biocompatibility of the phytosynthesized AgNPs, as they had no adverse effects on insect larvae viability. These findings emphasize the potential of targeted AgNPs synthesized from viticultural waste as environmentally friendly antimicrobial agents with minimal impact on higher organisms.

Localization of RNAs to the Mitochondria - Mechanisms and Functions.

The mammalian mitochondrial proteome comprises over 1000 proteins, with the majority translated from nuclear-encoded messenger RNAs (mRNAs). Mounting evidence suggests many of these mRNAs are localized to the outer mitochondrial membrane (OMM) in a pre-or co-translational state. Upon reaching the mitochondrial surface, these mRNAs are locally translated to produce proteins that are co-translationally imported into mitochondria. Here, we summarize various mechanisms cells employ to localize RNAs, including transfer RNAs (tRNAs), to the OMM and recent technological advancements in the field to study these processes. While most early studies in the field were carried out in yeast, recent studies reveal RNA localization to the OMM and their regulation in higher organisms. Various factors regulate this localization process, including RNA sequence elements, RNA binding proteins (RBPs), cytoskeletal motors, and translation machinery. In this review, we also highlight the role of RNA structures and modifications in mitochondrial RNA localization and discuss how these features can alter the binding properties of RNAs. Finally, in addition to RNAs related to mitochondrial function, RNAs involved in other cellular processes can also localize to the OMM, including those implicated in the innate immune response and piRNA biogenesis. As impairment of mRNA localization and regulation compromise mitochondrial function, future studies will undoubtedly expand our understanding of how RNAs localize to the OMM and investigate the consequences of their mislocalization in disorders, particularly neurodegenerative diseases, muscular dystrophies, and cancers.

Novel Ion Channel Genes in Malaria Parasites.

Ion channels serve many cellular functions including ion homeostasis, volume regulation, signaling, nutrient acquisition, and developmental progression. Although the complex life cycles of malaria parasites necessitate ion and solute flux across membranes, the whole-genome sequencing of the human pathogen Plasmodium falciparum revealed remarkably few orthologs of known ion channel genes. Contrasting with this, biochemical studies have implicated the channel-mediated flux of ions and nutritive solutes across several membranes in infected erythrocytes. Here, I review advances in the cellular and molecular biology of ion channels in malaria parasites. These studies have implicated novel parasite genes in the formation of at least two ion channels, with additional ion channels likely present in various membranes and parasite stages. Computational approaches that rely on homology to known channel genes from higher organisms will not be very helpful in identifying the molecular determinants of these activities. Given their unusual properties, novel molecular and structural features, and essential roles in pathogen survival and development, parasite channels should be promising targets for therapy development.

The molecular circadian rhythms regulating the cell cycle.

The circadian clock controls the expression of a large proportion of protein-coding genes in mammals and can modulate a wide range of physiological processes. Recent studies have demonstrated that disruption or dysregulation of the circadian clock is involved in the development and progression of several diseases, including cancer. The cell cycle is considered to be the fundamental process related to cancer. Accumulating evidence suggests that the circadian clock can control the expression of a large number of genes related to the cell cycle. This article reviews the mechanism of cell cycle-related genes whose chromatin regulatory elements are rhythmically occupied by core circadian clock transcription factors, while their RNAs are rhythmically expressed. This article further reviews the identified oscillatory cell cycle-related genes in higher organisms such as baboons and humans. The potential functions of these identified genes in regulating cell cycle progression are also discussed. Understanding how the molecular clock controls the expression of cell cycle genes will be beneficial for combating and treating cancer.

Colonial Microcystis' biomass affects its shift to diatom aggregates under aeration mixing.

The effect of hydrodynamic mixing on controlling Microcystis blooms or changing the algal community to diatom dominance has been widely studied; however, the effects of colonial Microcystis biomass on the development of the algal community are poorly known. Here, in order to study the changes in Microcystis blooms under continuous aeration mixing, an experiment was carried out in a greenhouse with factors of varying biomass of Microcystis and inorganic nitrogen and phosphorus enrichment in summer. There were three chlorophyll a (Chl-a) levels in six treatments: low Chl-a level of 68.4μgL-1 (treatments L, L-E), medium Chl-a level of 468.7μgL-1 (treatments M, M-E), and high Chl-a level of 924.1μgL-1 (treatments H, H-E). Treatments L-E, M-E and H-E were enriched with the same inorganic nitrogen and phosphorus nutrients. During the experiment of 30days, the concentration of Microcystis and Chl-a decreased, and diatom Nitzschia palea cells appeared in all the treatments, which became dominant in treatments M, M-E, H and H-E, with the highest biomass of 9.41 ± 1.96mgL-1 Nitzschia in treatment H-E on day 30. The rank order of the biomass of Nitzschia from low to high was (L = L-E) < (M = M-E) < H < H-E (P < 0.05). In addition, Nitzschia cells were aggregates attached to Microcystis colonies in all the treatments. The results showed that the initial biomass of colonial Microcystis affected the algal shift from Microcystis dominance to Nitzschia dominance. However, the enriched inorganic nitrogen and phosphorus was beneficial for the Nitzschia increase in the high biomass treatment alone. The shift from Microcystis dominance to diatom dominance under continuous aeration mixing may be caused by low light conditions as well as the nutrients released from Microcystis decay. Moreover, the aerobic condition caused by aeration mixing maintained the colonial mucilaginous sheath to support the growth of Nitzschia cells in aggregation. This study found for the first time that Microcystis blooms could shift to diatom Nitzschia dominance in aggregates. It provided a method to control and manipulate Microcystis blooms to diatom dominance through continuous aeration mixing to proper biomass of Microcystis colonies. The shift to diatoms dominance would provide more high quality food organisms for aquaculture and be beneficial to the materialcycling and energy flowing in food web dynamics.

Assessment of Heavy Metal Accumulation in Freshwater Fishes in Irrigation Tanks, Anuradhapura

 &#x0D; Sri Lanka is well known for its dense freshwater irrigation tanks, especially in dry zones, which play an important role in sustaining both the environment and human livelihoods by providing essential resources such as drinking water, irrigation for agriculture, and nutrition through fish proteins. However, heavy metal contamination poses a significant threat to the sustainability of these valuable freshwater irrigation tanks due to their persistence and non-biodegradability. These heavy metals tend to accumulate in living organisms and biomagnified and have harmful effects on high tropic level organisms like humans who rely on aquatic fish species via food chains. This study was carried out to assess the heavy metal accumulation in muscle and liver parts of freshwater fishes, Tilapia (Oreochromis sp.), and striped snakehead; Lula (Channa striata) in Kammalakkulama, Hammillewa, Kirindegama, and Madawalagama tanks in Anuradhapura district, Sri Lanka. The Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyse the randomly collected fish samples for total Cadmium (Cd), Arsenic (As), Lead (Pb), and Mercury (Hg) in the tanks. The results indicated a significant difference (p&lt;0.05) in the detected concentrations of heavy metal levels in tested samples among the four tanks. The highest concentrations of Cd (2.098 mg/kg) and As (0.366 mg/kg) were recorded in the liver of Tilapia in the Kammalakkulama tank. The highest Pb (5.509 mg/kg) and Hg (2.015 mg/kg) concentration was recorded in the Tilapia muscle in the Hammillewa tank and the Lula muscle in the Madawalagama tank respectively exceeding the WHO/FAO standards. The accumulation levels of these heavy metals were higher in the fish liver compared to their muscle in most of the samples. Arsenic (As) showed a significant positive linear relationship (R2=0.531) between their dry body weight and accumulated concentration in the Tilapia muscle. The canonical discriminant analysis showed a significant differentiation among the four tanks concerning heavy metal levels in fish tissues.&#x0D;  &#x0D; Keywords: Channa striata, Heavy metals, Irrigation tanks, ICP-MS, Oreochromis sp.

Assessing the Effectiveness of Lateral and Semi Fowler’s Position on Selected Patients Admitted with Respiratory Problems in Different Hospitals

Introduction: Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible in higher organisms and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura, pleural cavity, the nerves and muscles of breathing. Positioning is one of the most frequently performed nursing activity in the critical care, often providing a central pivotal focus for planning other nursing activity. Lateral position involves the patient lying on either patient’s right or left side. Semi Fowler’s Position is a position in which a patient is positioned on their back with the head and trunk raise to 30 degrees. So, the main objective of this study was to compare and evaluate the effectiveness after giving Lateral position in group 1 &amp; Semi Fowler’s position in group 2 among patients admitted with Respiratory problems. Method: A comparative study was conducted to assess the effectiveness of Lateral position v/s Semi Fowler’s position on selected Respiratory Parameters among the patients admitted with Respiratory problems for which 40 samples were selected by non-random purposive sampling and the data was collected by assessing the selected respiratory parameters (blood pressure, oxygen saturation, breath holding time, respiration rate &amp; heart rate) using instruments. Quantitative Research Approach was used in this study and research design was Quasi Experimental Research Design. The collected data was analyzed by Descriptive and Inferential Statistics. Result: Majority of the patients are male as compared to female and above 51 years of age. On the basis of comparing the posttest mean values of both the group, the posttest mean value (417.05) of group 2 (Semi Fowler’s position) is much higher than the posttest mean value (403.1) of group 1 (Lateral position). The result revealed that both the positions are effective to improve the respiratory parameters but on the basis of mean post test score the semi fowler’s position is more effective when compared to lateral position on respiratory parameters. The t value is found to be 3.022 with the significance level of p&lt;0007. Therefore, Hypothesis H3 is accepted. Conclusion: From the finding of the study, the respiratory parameters were improved in semi fowler’s position as compared to lateral position. Paired ‘t’ value was significantly higher where p value is &lt;0.05. Thus, it is concluded that the Semi Fowler’s position is highly effective to improve the selected Respiratory Parameters on the patients admitted with Respiratory Problems.

Excess dietary sugar impairs Drosophila adult stem cells via elevated reactive oxygen species-induced JNK signaling.

High-sugar diets (HSDs) often lead to obesity and type 2 diabetes, both metabolic syndromes associated with stem cell dysfunction. However, it is unclear whether excess dietary sugar affects stem cells. Here, we report that HSD impairs stem cell function in the intestine and ovaries of female Drosophila prior to the onset of insulin resistance, a hallmark of type 2 diabetes. Although 1 week of HSD leads to obesity, impaired oogenesis and altered lipid metabolism, insulin resistance does not occur. HSD increases glucose uptake by germline stem cells (GSCs) and triggers reactive oxygen species-induced JNK signaling, which reduces GSC proliferation. Removal of excess sugar from the diet reverses these HSD-induced phenomena. A similar phenomenon is found in intestinal stem cells (ISCs), except that HSD disrupts ISC maintenance and differentiation. Interestingly, tumor-like GSCs and ISCs are less responsive to HSD, which may be because of their dependence on glycolytic metabolism and high energy demand, respectively. This study suggests that excess dietary sugar induces oxidative stress and damages stem cells before insulin resistance develops, a mechanism that may also occur in higher organisms.

Action Mechanism and Side Effects of Tetrodotoxin

Tetrodotoxin (TTX) is one of the most toxic neuro-toxins found in the world at present. This drug has been widely used in the medical field, such as treating cancer related pain and severe arrhythmias. It is widely distributed and has been found in various high and low organisms such as aquatic and terrestrial organisms. But the source of the TTX and detoxification methods still need to be studied, so the study of the TTX is very significant. At the same time, TTX can block sodium ion channels, has obvious analgesic effect, and also has antiarrhythmia, abandon drug addiction and other effects. As a result, TTX has high medical and commercial value. This research will mainly summarize the pharmacological action, side effects of TTX and its underlying principle. In addition, it is expected that this study can provide new ideas for the study of new functions of TTX and the treatment of new diseases.

The Viable but Non-Culturable (VBNC) State, a Poorly Explored Aspect of Beneficial Bacteria.

Many bacteria have the ability to survive in challenging environments; however, they cannot all grow on standard culture media, a phenomenon known as the viable but non-culturable (VBNC) state. Bacteria commonly enter the VBNC state under nutrient-poor environments or under stressful conditions. This review explores the concept of the VBNC state, providing insights into the beneficial bacteria known to employ this strategy. The investigation covers different chemical and physical factors that can induce the latency state, cell features, and gene expression observed in cells in the VBNC state. The review also covers the significance and applications of beneficial bacteria, methods of evaluating bacterial viability, the ability of bacteria to persist in environments associated with higher organisms, and the factors that facilitate the return to the culturable state. Knowledge about beneficial bacteria capable of entering the VBNC state remains limited; however, beneficial bacteria in this state could face adverse environmental conditions and return to a culturable state when the conditions become suitable and continue to exert their beneficial effects. Likewise, this unique feature positions them as potential candidates for healthcare applications, such as the use of probiotic bacteria to enhance human health, applications in industrial microbiology for the production of prebiotics and functional foods, and in the beer and wine industry. Moreover, their use in formulations to increase crop yields and for bacterial bioremediation offers an alternative pathway to harness their beneficial attributes.

Synergistic toxicity induced by the co-exposure of tenuazonic acid and patulin in Caenorhabditis elegans: Daf-16 plays an important regulatory role

Tenuazonic acid (TeA) and patulin (PAT), as the naturally occurring mycotoxins with various toxic effects, are often detected in environment and food chain, has attracted more and more attention due to their widespread and high contaminations as well as the coexistence, which leads to potential human and animals’ risks. However, their combined toxicity has not been reported yet. In our study, C. elegans was used to evaluate the type of combined toxicity caused by TeA+PAT and its related mechanisms. The results showed that TeA and PAT can induce synergistic toxic effects based on Combination Index (CI) evaluation model (Chou-Talalay method), that is, the body length, brood size as well as the levels of ROS, CAT and ATP were significantly affected in TeA+PAT-treated group compared with those in TeA- or PAT-treated group. Besides, the expressions of oxidative (daf-2, daf-16, cyp-35a2, ctl-1, ctl-3, pmk-1, jnk-1, skn-1) and intestinal (fat-5, pod-2, egl-8, pkc-3, ajm-1, nhx-2) stress-related genes were disrupted, among which daf-16 displayed the most significant alternation. Further study on daf-16 gene defective C. elegans showed that the damages to the mutant nematodes were significantly attenuated. Since daf-2, daf-16, jnk-1 and pmk-1 are evolutionarily conserved, our findings could hint synergistic toxic effects of TeA+PAT on higher organisms.

Essential omega-3 fatty acids are depleted in sea ice and pelagic algae of the Central Arctic Ocean.

Microalgae are the main source of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential for the healthy development of most marine and terrestrial fauna including humans. Inverse correlations of algal EPA and DHA proportions (% of total fatty acids) with temperature have led to suggestions of a warming-induced decline in the global production of these biomolecules and an enhanced importance of high latitude organisms for their provision. The cold Arctic Ocean is a potential hotspot of EPA and DHA production, but consequences of global warming are unknown. Here, we combine a full-seasonal EPA and DHA dataset from the Central Arctic Ocean (CAO), with results from 13 previous field studies and 32 cultured algal strains to examine five potential climate change effects; ice algae loss, community shifts, increase in light, nutrients, and temperature. The algal EPA and DHA proportions were lower in the ice-covered CAO than in warmer peripheral shelf seas, which indicates that the paradigm of an inverse correlation of EPA and DHA proportions with temperature may not hold in the Arctic. We found no systematic differences in the summed EPA and DHA proportions of sea ice versus pelagic algae, and in diatoms versus non-diatoms. Overall, the algal EPA and DHA proportions varied up to four-fold seasonally and 10-fold regionally, pointing to strong light and nutrient limitations in the CAO. Where these limitations ease in a warming Arctic, EPA and DHA proportions are likely to increase alongside increasing primary production, with nutritional benefits for a non-ice-associated food web.

Lipid-anchored proteasomes control membrane protein homeostasis.

Protein degradation in eukaryotic cells is mainly carried out by the 26S proteasome, a macromolecular complex not only present in the cytosol and nucleus but also associated with various membranes. How proteasomes are anchored to the membrane and the biological meaning thereof have been largely unknown in higher organisms. Here, we show that N-myristoylation of the Rpt2 subunit is a general mechanism for proteasome-membrane interaction. Loss of this modification in the Rpt2-G2A mutant cells leads to profound changes in the membrane-associated proteome, perturbs the endomembrane system, and undermines critical cellular processes such as cell adhesion, endoplasmic reticulum-associated degradation and membrane protein trafficking. Rpt2G2A/G2A homozygous mutation is embryonic lethal in mice and is sufficient to abolish tumor growth in a nude mice xenograft model. These findings have defined an evolutionarily conserved mechanism for maintaining membrane protein homeostasis and underscored the significance of compartmentalized protein degradation by myristoyl-anchored proteasomes in health and disease.

1222. Impact of Microbiology Reporting Changes in Treatment of AmpC Bloodstream Infections

Abstract Background Recent literature suggests that AmpC production may be overcalled in Enterobacterales, leading to unnecessary broad-spectrum antimicrobial utilization. The Infectious Diseases Society of America (IDSA) has since reassessed classification of high and low risk organisms with inducible AmpC expression. With this updated guidance, our health system approved changes to our microbiology reporting of AmpC producers in an effort to guide prescribing of appropriate antibiotics. The primary objective of this project was to compare antibiotic prescribing patterns for high and low risk AmpC producers in patients with bloodstream infections (BSI) based on the addition of appended comments to antimicrobial susceptibility results. Methods This multicenter, retrospective, cohort study included patients with BSI from October 2022 to March 2023who received at least 48 hours of antimicrobial therapy for the following high and low risk AmpC producers: Citrobacter spp., Enterobacter spp., Klebsiella aerogenes, Serratia spp., Morganella spp., Providencia spp. The primary endpoint was the number of patients placed on optimal therapy based on adherence to the appended microbiology comment and IDSA guidance. Secondary endpoints included time to effective treatment, time to optimal treatment, duration of therapy, 30 day mortality, microbiological failure, microbiological relapse, 30 day readmission, length of stay, and hospital acquired Clostridioides difficile infection. Results A total of 191 positive blood cultures were identified with 93 patients (pre-appended comment = 57; post-appended comment = 36) meeting inclusion criteria. Patients were more likely to receive optimal therapy post-appended comment based on IDSA guidance for BSI (38.6% vs 72.2%, OR 4.14; 1.68-10.21). When stratified by high risk and low risk organism, the number of patients on optimal therapy increased in the post-appended comment group but was not statistically significant (high risk: 70.3% vs 88%, OR 3.08; 0.72-13.32; low risk: 10% vs 36.3%, 5.14; 0.92-28.50). No difference in secondary outcomes were detected. Conclusion Implementation of an appended microbiology note has the potential to have a positive impact on antimicrobial prescribing patterns in treatment of AmpC bloodstream infections. Disclosures All Authors: No reported disclosures

Effect of heavy metals on the antioxidant system of the acid-tolerant microalga Coccomyxa onubensis

Coccomyxa onubensis (C. onubensis) is an acid-tolerant microalga whose ecosystem (Tinto River, Huelva, Spain) contains high amounts of different heavy metals. However, the potential of this microalga to remove these pollutants from the environment has still not been studied. Thus, this work evaluates the tolerance and physiological response of this microalga in the presence of three heavy metals, copper, cadmium, and mercury, and the metalloids As (III) and As (V). The results demonstrated that C. onubensis is able to improve its growth parameters with the presence of copper in the culture medium until concentrations of 2 mM Cu2+ and also shows high tolerance to other heavy metals and metalloids tested, such as Cd2+, As(III), As(V) or Hg2+. Moreover, this microalga seems to be a high arsenic accumulator organism, showing its high potential for arsenic bioremediation processes. Finally, the characterization of three antioxidant enzymes and their evaluation under heavy metal stress was performed. The results showed that ascorbate peroxidase (APX, EC:1.11.1.11), catalase (CAT, EC:1.11.1.6), and glutathione reductase (GR, EC:1.6.4.2) were upregulated to different degrees when C. onubensis was cultivated under heavy metal stress.

High trophic level organisms and the complexity of soil micro-food webs at aggregate scale regulate carbon accumulation in cropland soils

Enhancing soil organic carbon (SOC) levels via improved fertilization strategies can promote soil health and support sustainable crop production. While bacteria and fungi play a key role in SOC accumulation, the effects of soil micro-food webs that include organisms from higher trophic levels remain uncertain. We sought to narrow this knowledge gap by clarifying the associations between SOC accumulation and soil micro-food webs at the aggregate scale under long-term (18 years) fertilization treatments, which included a no-fertilizer control (Ctrl), synthetic fertilizers (NPK), and partial synthetic nitrogen replacement with pig slurry (OMNPK) or crop straw (RSDNPK). The concentration of SOC was significantly increased by fertilization following the order RSDNPK (13.1 g kg−1) > OMNPK (11.4 g kg−1) > NPK (9.1 g kg−1) > Ctrl (6.4 g kg−1). Nematodes and protists accounted for approximately 20% of all nodes in the multitrophic networks. Fertilization increased network complexity at the aggregate scale by 1–4 times across different sampling dates (P < 0.05). In all aggregate classes, the functionally important (FI) nematodes, protists, and bacterial taxa involved in soil carbon cycle had higher relative abundances under the fertilization treatments than under the Ctrl (P < 0.05). Structural equation modeling further indicated that besides soil microbes, network complexity, FI nematodes and protists were important to SOC accumulation. Compared with NPK, the key moments during which these soil biological attributes strongly regulated SOC under OMNPK and RSDNPK were delayed to late growth stages of maize. In conclusion, the increased network complexity and relative abundance of functionally important organisms from higher trophic levels of the soil micro-food webs at certain periods are vital contributors to effective SOC accumulation under fertilization regimes that include organic amendments.

A gonadal gap junction INX-14/Notch GLP-1 signaling axis suppresses gut defense through an intestinal lysosome pathway.

Gap junctions mediate intercellular communications across cellular networks in the nervous and immune systems. Yet their roles in intestinal innate immunity are poorly understood. Here, we show that the gap junction/innexin subunit inx-14 acts in the C. elegans gonad to attenuate intestinal defenses to Pseudomonas aeruginosa PA14 infection through the PMK-1/p38 pathway. RNA-Seq analyses revealed that germline-specific inx-14 RNAi downregulated Notch/GLP-1 signaling, while lysosome and PMK-1/p38 pathways were upregulated. Consistently, disruption of inx-14 or glp-1 in the germline enhanced resistance to PA14 infection and upregulated lysosome and PMK-1/p38 activity. We show that lysosome signaling functions downstream of the INX-14/GLP-1 signaling axis and upstream of PMK-1/p38 pathway to facilitate intestinal defense. Our findings expand the understanding of the links between the reproductive system and intestinal defense, which may be evolutionarily conserved in higher organism.