Search Results (68)

Calcareous tropical green macroalgae of the genus Halimeda are key reef-builders, yet the drivers of their diversification and population dynamics remain poorly understood. This study analyzed the species diversity of Halimeda in the Xisha (Paracel) Islands based on tufA gene sequences, focusing on evaluating the genetic diversity, population structure, and historical dynamics of two widespread species—Halimeda discoidea and Halimeda macroloba. The results indicate new records of Halimeda cylindracea and Halimeda cf. stuposa in the Xisha (Paracel) Islands. More importantly, H. discoidea and H. macroloba exhibited significantly different evolutionary histories. Specifically, H. discoidea showed a highly fragmented population structure, restricted gene flow, and a multimodal mismatch distribution, suggesting a complex historical process or long-term stability. In contrast, H. macroloba exhibited lower population differentiation, extensive gene flow, and non-significant neutrality test results, indicating long-term demographic stability without recent, drastic population events. Further validation based on gene flow analysis and divergence time estimation revealed that the lineage divergence of H. discoidea is older, while H. macroloba represents a lineage with a relatively younger evolutionary origin restricted to the Indo-Pacific region. This striking dichotomy clearly illustrates the interplay between intrinsic species-specific traits (e.g., dispersal capacity) and extrinsic historical factors (e.g., paleo-oceanographic events), leading to contrasting evolutionary outcomes among widespread marine taxa. By elucidating how differing evolutionary histories influence patterns of genetic diversity, this study provides a predictive framework for evaluating the resilience and guiding conservation priorities for critical marine calcifiers in the context of rapid environmental change. Full article

The intestine is a multifunctional organ responsible for digestion, nutrient absorption, metabolic regulation, and innate immunity. In flatworms, recent studies have highlighted the importance of intestine-enriched genes expressed strongly in cells of the digestive tract. These genes are not only involved in digestion, nutrient uptake, transport, metabolism, and feeding behavior, but also in the modulating dynamics of stem cells (neoblasts). In Macrostomum lignano, the molecular mechanisms regulating interaction between digestive and neural processes remain poorly understood, as in other free-living flatworms. Therefore, identifying the genes required for intestinal integrity and feeding behavior is essential for understanding the underpinning mechanisms. In this study, we examined intestine-enriched candidate genes predicted to be involved in cell differentiation and maintenance of the intestine in M. lignano and whether the knockdown of these genes affects other tissues’ functioning. Using RNAi-mediated gene silencing, we identified four genes (kri1, wbp2nl, Mlig-tuf1, and Mlig-tuf2) whose knockdown causes pronounced phenotypes, including reduced feeding, fasting behavior, decreased body size and cell proliferation, low reproduction, and altered expression of an intestine-specific apob promoter. We have characterized their roles in intestinal homeostasis and neoblast dynamics and discussed potential mechanisms linking gene disruption to changes in feeding behavior. Full article

Hemorrhagic septicemia (HS) is a fulminant bovine disease across Asia and Africa, yet Pasteurella multocida (P. multocida) isolated from yak is poorly reported. We isolated strain NQ01 from a fatal HS case in Xizang, China and identified it as P. multocida B:2 by morphology, Gram stain, and PCR (kmt1⁺, bcbD⁺, LPS L2). NQO1 formed smooth, non-hemolytic colonies. After Gram staining, the cells appeared as red rods with bipolar staining. Antimicrobial testing showed broad susceptibility to β-lactams, aminoglycosides, tetracyclines, fluoroquinolones, midecamycin, florfenicol, polymyxin, and vancomycin, with resistance to metronidazole, trimethoprim sulfamethoxazole, and clindamycin. Streptomycin and ofloxacin had intermediate activity. In mice, the intraperitoneal and intranasal LD₅₀ values were 40.64 CFU/mL and 9.53 × 10⁶ CFU/mL, respectively. The intranasal fatal cases were characterized by bacteremia with multifocal disseminated intravascular coagulation involving lung, liver, and spleen. The complete genome comprises a single 2.33 Mb chromosome (40.47% GC, 2115 CDS, no plasmids) with only one resistance gene (Eco_EFTu_PLV) and 28 virulence genes spanning adhesion (tadA, rcpA, ppdD, pilB, tuf/tufA, htpB, PM_RS00430, PM_RS00425, PM_RS08640), immune modulation (lpxB/C/D, msbB, manB, rfaE/F, gmhA/lpcA, kdsA, pgi, wecA, galE, bexD’, ABZJ_RS06285, ABD1_RS00310), and nutritional/metabolic factor (hgbA, hemR, hemN), plus a YadA-like factor. Phylogenetically, NQ01 clusters with regional B:2 bovine/yak isolates. Collectively, these data define NQ01 as a highly virulent, low-resistance yak isolate and a practical model for natural-route HS pathogenesis and targeted control in high-altitude pastoral settings yaks. Full article

(1) Studying the spatial distribution of wingless arthropods restricted to the Earth’s surface presents numerous challenges. In this study, we focused on the spatial distribution of terrestrial isopods (Oniscidea) within a managed forest ecosystem, examining relationships among abundance, variance, occupancy, and clumpiness (i.e., aggregation) to highlight their significant roles in the observed phenomena. (2) Terrestrial isopods were collected using pitfall traps along a gradient spanning deforested and forested areas. For analysis, we employed summary statistics to describe the community using 18 different coefficients. Abundance–variance and abundance–occupancy models, together with Taylor’s power law and ordination symbol plots were performed. (3) Nearly 1000 individuals representing 8 species were identified and analyzed. All species exhibited a clumped distribution; however, Ligidium hypnorum displayed the highest degree of clumpiness, which resulted in notably low frequency and constancy despite its high overall abundance. Shrubs were the habitat with the highest rate of aggregation. Most species concentrated their individuals in just up to 5 of the 75 pitfall traps, with the remaining traps typically containing fewer or no individuals. (4) Species that are highly abundant on a local scale can be surprisingly limited in their spatial distribution, making their assumed dominance questionable and causing them to deviate from established trends. Awareness of species-specific traits and attention to such details can progressively improve the interpretation of observed ecological patterns. Full article

‘Candidatus Phytoplasma solani’ is the causal agent of the Bois noir (BN), affecting grapevine worldwide. The complex epidemiology of BN, which involves multiple ‘Ca. P. solani’ host plants and insect vectors, as well as the occurrence of recovery (loss of symptoms on grapevine canopy), makes disease investigations and containment in vineyards difficult. To achieve early detection of ‘Ca. P. solani’, a droplet digital PCR (ddPCR)-based approach and quantitative (q)PCR assay were compared, testing specific primers based on the elongation factor Tu (tuf) gene using SYBR Green chemistry. The regression curve analysis of the ddPCR assay showed good linearity. Compared with the qPCR method, the sensitivity of ddPCR improved about 10-fold. The analysis of grapevine roots spiked with serial dilutions of ‘Ca P. solani’. PCR tuf fragments showed that qPCR was inhibited, while ddPCR was not affected. Testing 66 grapevine samples from 50 grapevine plants, the ddPCR provided superior diagnostic performance compared to qPCR in roots of symptomatic plants (75% detected by ddPCR, 41.6% by qPCR), roots of recovered plants (58.8% detected by ddPCR, 25% by qPCR), and asymptomatic leaf tissues from recovered plants (75% detected by ddPCR, 25% by qPCR). The ddPCR analysis allowed us to detect ‘Ca. P. solani’ on 40% of leaf samples from recovered plants and 20% of roots from asymptomatic plants. No differences among ddPCR and qPCR were found in detecting phytoplasma on symptomatic leaf samples. The ddPCR assay allowed the absolute quantification of ‘Ca. P. solani’ in complex matrices, such as roots, and when low titer of phytoplasma is present. Full article

Water scarcity poses a substantial challenge for turfgrass irrigation in the drought- and heat-stressed Desert Southwest region of the United States. Bermudagrass (Cynodon spp.), renowned for its exceptional drought resistance, is the predominant warm-season turfgrass in the region. Selecting and using drought-resistant bermudagrass cultivars remains a primary strategy for sustaining the turfgrass industry in the region. This study evaluated 48 hybrid bermudagrasses (Cynodon dactylon × C. transvaalensis Burtt-Davy), including two commercial cultivars (‘TifTuf’ and ‘Tifway’, as controls), under 80% × ETo (0.8ET), 60% × ETo (0.6ET) and 40% × ETo (0.4ET) reference evapotranspiration (ETo) replacement irrigation systems at Maricopa, AZ. The experiment was laid out in a split-plot design with two replications, where the 3 irrigation treatments were assigned to main plots and 48 genotypes were in sub-plots. Analysis of data from two years (2022 and 2023) revealed significant differences among bermudagrass hybrids, irrigation treatments, and their interaction effects. The hybrids exhibited substantial variation for spring green-up, density, turf color, and quality. With the largest deficit irrigation treatment 40% × ETo (0.4ET), OSU2104, OSU2106, and OSU2105 showed greater mean greenness and aesthetic quality scores than recorded for ‘TifTuf’ (6.5), a popular drought-tolerant cultivar. The results highlight the prevalence of genetic variation in germplasm with potential for development of improved varieties for drought tolerance. Full article

Nowadays, members of the genus Enterobacter have been documented as human and aquaculture pathogens. To date, no reports have described Enterobacter bugandensis infecting Hippocampus abdominalis. In the present study, an isolate of E. bugandensis, designated H4, was identified as a causative pathogen in cultured H. abdominalis following Koch’s postulate, and its virulence properties were further described. The isolate’s genome consisted of a single circular chromosome and harbored several virulence and resistance genes, including, but not limited to, csgG, acrB, hcp, gndA, galF, rpoS, fur, rcsB, and phoP involved in adherence, antimicrobial activity, effector delivery systems, immune modulation, and regulation, as well as baeR, blaACT-49, ramA, hns, ftsI, acrA, gyrA, fabI, crp, oqxB, parE, gyrB, phoP, rpoB, tuf, ptsI, and fosA2 functioning against aminoglycoside, cephamycin, disinfecting agent and antiseptic, fluoroquinolone, macrolide, peptide, and other antimicrobials. Additionally, the isolate exhibited multiple resistance to cephalosporins, penicillins, and tetracyclines and demonstrated a median lethal dose (LD₅₀) of 4.47 × 10⁵ CFU/mL in H. abdominalis. To our knowledge, this is the first study to describe E. bugandensis infecting H. abdominalis. These findings highlight the zoonotic potential of E. bugandensis and underscore the need for targeted health management in seahorse farming. Full article

Background/Objectives: Meningitis due to the species Streptococcus is a severe central nervous system infection caused by various microorganisms belonging to Streptococcus spp. Its accurate identification is critical for effective clinical management. This study aimed to identify Streptococcus spp. causing meningitis in Greece over a nine-year period using PCR and sequencing-based methods. Methods: A total of 189 clinical samples, collected between 2015 and 2024 from patients suffering from meningitis and/or septicemia, were analyzed by the use of a combination of multiplex polymerase chain reaction (PCR) assays and tuf gene sequencing for further species identification. Results: Sample analysis identified 70 samples as S. pyogenes (18.52%) (GAS) and S. agalactiae (18.52%) (GBS), while 119 (62.96%) were recorded as non-typable Streptococcus spp. Further analysis using sequencing methods revealed that the most frequent Streptococcus spp. belonged to the mitis group (42.86%) and the pyogenic group (20.17%). A higher prevalence was observed in children aged 0–14 years old and adults over 50 years old. Conclusions: This study highlights the use of molecular diagnostics in identifying other Streptococcus spp., providing insights into age-related susceptibility and epidemiological trends. Future studies are needed to explore the pathogenic role of the identified Lactococcus spp. Full article

The ability of terrestrial isopods (Crustacea: Isopoda: Oniscidea) to protect themselves effectively from predation by birds has never been tested. They are equipped with glands producing chemical substances; moreover, some species show conspicuous coloration, which might suffice as an aposematic signal. We evaluated the palatability of isopods to birds. We tested the responses of Parus major captured in the wild (and thus possessing some experience with common native isopod species) to the following isopod species: Porcellio scaber (native, inconspicuous), Oniscus asellus (native, moderately conspicuous), Armadillo officinalis (non-native, moderately conspicuous), Armadillidium versicolor (native, conspicuous), and Armadillidium gestroi (non-native, conspicuous). We compared bird responses to isopods with reactions to the Blaptica dubia, an edible roach very similar to isopods in size and appearance. Isopods were better protected from bird attacks than roaches; however, their color pattern did not affect the level of protection. Birds were able to differentiate isopods from the roach; in experiments, where we presented isopod and roach individuals together, the birds hesitated longer in attacking and observed both prey items for a longer time. Non-native species either profited from the generalization of the protection of native isopods or from neophobia. Some isopods elicited significantly more discomfort behavior in birds, suggesting differences in the chemical protection among the tested species. Full article

Fertilizer application is a critical component of turfgrass management as it influences growth, color, stress tolerance, and overall quality. However, limited information exists on how fertilizer application, particularly nitrogen (N), affects hybrid bermudagrass performance and actual plant evapotranspiration (ET_a) in both well-watered and deficit irrigation scenarios. A 7-week greenhouse experiment was conducted over two replicated runs to evaluate responses of ‘TifTuf’ hybrid bermudagrass (Cynodon dactylon × C. traansvalensis Burtt Davy) to three nitrogen rates (0, 2.4, and 4.8 g N m⁻² month⁻¹) and three irrigation levels (1.0, 0.65, and 0.30 × ET_a). Fertilized turfgrass exhibited 11–12% greater ET_a compared to unfertilized turfgrass, with no significant differences between the two fertilizer rates. Under well-watered conditions (1.0 × ET_a), the high nitrogen rate significantly improved visual quality (7.8) relative to the unfertilized control (7.1) and the low-rate treatment (7.4). High-rate fertilizer application significantly enhanced visual quality at both deficit levels (7.2 and 6.6, at 0.65 and 0.30 × ET_a, respectively) compared to the unfertilized control (6.2 and 5.9, at 0.65 and 0.30 × ET_a, respectively). At 0.30 × ET_a, low-rate fertilizer application also significantly improved visual quality (7.0) compared to the unfertilized control. Soil nitrate-N levels increased with higher nitrogen application (1.30 ppm, 0.48 ppm, and 0.37 ppm, respectively, for high-rate, low-rate, and unfertilized), and shoot tissue analysis revealed greater N concentration in fertilized turfgrass (1.51%, 1.24%, and 0.85%, respectively, for high-rate, low-rate, and unfertilized). Clipping production and water use efficiency (WUE) were also improved with fertilization, although root development was hindered at the 0.30 × ET_a irrigation level. These findings demonstrate that nitrogen fertilization improves visual quality, shoot growth, WUE, and drought response; however, tradeoffs such as elevated water use and nitrate-N leaching risk necessitate careful management to balance turfgrass performance with water conservation and ecosystem service preservation. Full article

Bermudagrass is a warm-season turfgrass commonly grown in drought-prone areas. Harnessing natural genetic variation available in germplasm is a principal strategy to enhance its resilience to drought stress. This study was carried out to assess the comparative performance of bermudagrass hybrids under drought conditions and their subsequent recovery following the drought period. A total of 48 hybrids, including 2 commercial cultivars, ‘Tifway’ and ‘TifTuf’, were established under optimum growth conditions in the greenhouse and then subjected to drought stress by withholding irrigation for four weeks. The dry-down experiment was laid out in a randomized complete block design with four replications. Turf color, visual quality, and active spectral reflectance data were collected weekly and used to assess the health and vigor of the hybrids during progression of the drought stress for four weeks and through recovery after rewatering. Analysis of variance revealed significant differences among the hybrids for color, visual quality, and spectral vegetation indices. A multivariate analysis grouped the hybrids into drought-tolerant with full recovery after rewatering, moderately tolerant, and susceptible to extended drought stress without recovery. These results showed the prevalence of genetic variation for drought tolerance and proved instrumental in the development of bermudagrass cultivars resilient to drought stress and improved water use efficiency. Full article

Understanding population genetic connectivity is crucial for the sustainability and persistence of marine biodiversity. As a fundamental reef-building macroalga of the coastal ecosystem, Halimeda macroloba Decaisne is one of the dominant intertidal seaweeds in the Indo-Pacific region. However, its genetic structure and population connectivity have been poorly recognized. Here, we explored the population genetic structure and genetic connectivity of H. macroloba using chloroplast tufA, rps3-rpl14, and rbcL. Our results indicated low genetic diversity and shallow population genetic structure at the intraspecific level, uncovering five genetic groups with six subdivided lineages in tufA and two genetic clusters in rps3-rpl14. We detected demographic expansion in the last glacial period of the Pleistocene and significantly asymmetric gene flow among different geographical units. We suggest that the southwestward ocean currents under the influence of northeast monsoon in the Indo-Pacific region are the main factor in shaping the present genetic structure, and the asexual reproduction of H. macroloba also plays an important role of the low genetic diversity pattern; in addition, the divergence between genetic clusters might be related to the historical isolation led by the paleoclimate oscillation in the Pleistocene. The Xisha Islands in the northern South China Sea might serve as a potential refugium of H. macroloba, which needs extra attention to conservation management. Given the limitation of sample size, we need to conduct more field work and carry out further research at a larger scale in the future. Our study provided new insights into the theory of population connectivity in the Indo-Pacific region and provided scientific basis for tropical costal seaweed conservation. Full article

Massive blooms of Ulva species, commonly known as green tides, pose serious ecological threats by disrupting coastal ecosystems and requiring costly removal efforts. This study presents a nature-based solution by seasonally valorizing Ulva ohnoi, a bloom-forming macroalga dominant in Jeju Island, South Korea. Biomass was collected across all four seasons and subjected to phylogenetic identification, biochemical characterization, and bioresource processing. Despite environmental fluctuations, tufA-based analysis confirmed U. ohnoi as the sole species present year-round. Carbohydrate content peaked in spring (55.35%) and was lowest in summer (45.74%), corresponding to maximum reducing sugar of 36.49 g/L in winter and 36.24 g/L in spring following acid-enzymatic hydrolysis. The maximum ethanol fermentation using Saccharomyces cerevisiae produced up to 17.12 g/L ethanol in spring with a yield of 0.47 g/g. Post-fermentation residues were enzymatically hydrolyzed into Ulva Ethanol Residue Medium (UERM), which supported yeast growth and fermentation comparable to commercial YPD medium, achieving final optical densities of 8.3–8.5 and ethanol production of 16.5–16.8 g/L. Alanine, valine, and proline were the most abundant amino acids in UERM, supporting its suitability as a nitrogen source. These findings highlight the potential of integrating green tide mitigation with renewable energy and nutrient recycling through seasonal, localized biorefineries aligned with circular marine bioeconomy principles. Full article

‘Candidatus Phytoplasma prunorum’ has been associated with severe disease in Prunus spp., which are commodities of economic importance in the USA. The introduction and establishment of ‘Ca. P. prunorum’ in the USA could result in huge economic losses, thus creating a need for validated diagnostic tools, which are the cornerstone of successful surveillance, quarantine, and eradication measures. Whole-genome comparisons led to the identification of a diagnostic marker gene specific to ‘Ca. P. prunorum’ (PE639). The PE639 assay was duplexed with an 18S rDNA plant internal control and compared to modified 23S (phytoplasmas) and imp (‘Ca. P. mali’) assays. The PE639 assay produced congruent results to 23S and imp assays for all metrics, demonstrating high linearity, repeatability, intermediate precision, and reproducibility. The limit of detection was comparable for all assays tested, and all demonstrated 100% analytical specificity, selectivity, and diagnostic specificity for their respective target species. Assays metrics were consistent across two platforms, the ABI QuantStudio™ 5 and Bio-Rad CFX96™ OPUS. A synthetic gBlocks™ control was designed and validated to work with all assays, as well as conventional PCR assays targeting 16S rDNA and tuf genes. These validated assays and synthetic control represent beneficial tools that support efforts to protect USA agriculture and facilitate safe trade. Full article

The taxonomic position of the green alga Capsosiphon fulvescens was first reported from Northern Europe and has since been reported from all over the world, including Korea. In Korea, C. fulvescens has been used as an essential edible economic alga for approximately 570 years, from the time of the Joseon Dynasty to the present, and is currently under development as a new aquaculture strain. Therefore, examining the taxonomic relationships between the European and Korean C. fulvescens is important. In this study, we analyzed nuclear 18S rDNA and ITS regions and compared them with the DNA sequences of authentic materials of North Atlantic C. fulvescens. Additionally, rbcL and tufA genes were sequenced to analyze genetic variations among populations. The results showed that the Korean and European C. fulvescens were different species. Moreover, the Korean C. fulvescens was distantly related to the North Atlantic C. fulvescens at the order level. Moreover, the Korean C. fulvescens formed a sister group with the North Pacific Pseudothrix borealis. Cryptic genetic diversity was observed at the intraspecific level among the Korean populations. These findings will help in tracing the origin of the Korean C. fulvescens and provide new genetic insights into this species. Full article