Biologia最新文献

Prunus serotina is one of the most widespread alien tree species in temperate European forests. Although numerous studies revealed both negative and positive impacts on native ecosystems, only a few assessed the quantitative impacts along a species abundance gradient, based on aboveground biomass of per capita effects. Here we studied how alpha diversity of forest understory changes with increasing aboveground biomass of P. serotina. In Wielkopolska National Park (W Poland) we established 92 plots in both nutrient-rich and poor Pinus sylvestris stands. We assessed the effects of P. serotina proportion on understory species composition using non-metric multidimensional scaling (NMDS). We also assessed the effects of P. serotina proportion on alpha diversity metrics using generalized mixed-effects linear models, accounting also for stand age, soil C:N ratio, and light availability. P. serotina biomass ranged from 0.0 to 34.29 Mg ha⁻¹ (with an average of 5.70 ± 0.83 Mg ha⁻¹), comprising 0% to 17.26% (with an average of 2.93 ± 0.43%) of total woody species biomass. NMDS revealed a lack of P. serotina proportion effects on understory species composition. We found small positive impacts of P. serotina proportion on total species richness (+ 8.8 species along a gradient with a 10% increase of P. serotina biomass proportion) and functional richness (+ 0.08). The positive impacts of P. serotina were mostly related to the confounding effect of two factors: an increase in light availability facilitates both the development of understory plants as well as the growth of P. serotina.

Lizard species of wide distribution can show differences in morphology and many other characteristics, in particular in the scutelation. In this study, we analyzed the variation of 22 meristic characters between sexes and among populations of Sceloporus variabilis from the state of Hidalgo in central Mexico. The variables such as dorsal scales, scales around the body, ventral scales, femoral pores, interfemoral scales, and lamellae of the fourth digit of the hindlimbs were different among populations; the population of San Pablo Tetlapayac presented the highest average values in these variables. A positive and significant relationship between snout–vent length and the number of ventral scales was found only in the females of San Pablo Tetlapayac and Santa Catarina. The variations recorded in the present study indicate an effect of environmental variation in the pattern of the number of scales, and suggest that both environmental conditions, such as precipitation and temperature, and ecological conditions, such as substrate or microhabitats, may be influencing differences in the number and size of scales among populations. Further studies on physiology and ecomorphology are necessary to determine the direction of variations in scutelation between sexes and populations.

In vitro culture experiments are crucial for studying chemically-mediated interactions in plants. However, the difficulty in distinguishing spores and sporelings of different bryophyte species hinders research on early developmental stages. Here we propose a modification of the sandwich technique, a standard method for studying plant allelopathic, and present a case study using two common mosses. As in the standard sandwich method, we have created a physical barrier using gelled medium, and inoculated spores of Tortula muralis and Syntrichia ruralis in two layers. To assess their intra- and interspecific interactions, we measured the green coverage of the protonemata using image analysis, and the degree of sporeling development using a categorical index. We successfully obtained physically separated sporelings of target and emitters from spores of these two species. The green coverage analysis showed no differences in any of the comparisons. However, the developmental index showed a negative effect of T. muralis on S. ruralis, whereas S. ruralis appeared to promote the development of T. muralis. The method proposed here is successful for culturing moss spores. The two inocula (the emitter and the receiver) are physically separated but the set-up allows the diffusion of water-soluble and volatile substances. For testing interactions at these early stages of the gametophyte, we recommend measuring the degree of development of moss sporelings rather than their coverage. Our results revealed both positive and negative interspecific interactions between T. muralis and S. ruralis sporelings. This supports that positive interactions in bryophytes may be more common than previously thought.

Diplonychus indicus, a tropical, skilled predatory water bug with a global distribution, has been studied for its predatory performance. In this study, a detailed account and a thorough assessment on the population dynamics, reproductive fecundity, and the various factors, viz., effect of space size, temperature, food deprivation, aquatic vegetation, competition, and prey density influencing the predatory performance of D. indicus have been portrayed. Over the course of a year, the population dynamics of D. indicus was observed in a permanent pond located in the Kanyakumari region of Tamil Nadu, Southern India. Except for temperature, D. indicus nymphs and adults, had a positive correlation with abiotic (temperature, pH, dissolved oxygen, and rainfall) and biotic (Culex larvae) parameters. With regard to reproductive fecundity, on an average, 20 female individuals of D. indicus produced 1062 eggs, with a maximum hatching percentage of 88.3 at water temperatures of 25–26 °C, and an incubation period of 9.0 ± 0.35 days. The stadial duration of nymphs was 77.68 days, with the Ist stage being the shortest (5.2 ± 0.32 days) and the Vth stage the longest (34.22 ± 4.12). The IVth stage followed by the Vth stage had the highest rates of survival from egg to adult. The predatory performance of D. indicus nymphs evaluated based on the following factors, viz., space size, temperature, starvation, vegetation, competition, and prey density, are as follows. Maximum number of prey (Culex larvae) predated (411.20 ± 8.76) was in circular experimental glass container of 1 L volume space size; at a temperature of 25 °C (11.20 ± 0.30); after 24 h of starvation (558.26 ± 2.56); in 2.0 g density of aquatic vegetation (388.16 ± 2.32); with six competitors (2484.60 ± 8.10); and at 80 prey density (28.52 ± 1.02). The current study provides a critical insight into these variables that are crucial in the predatory performance of their prey, and are successful parameters in establishing a specific predator-prey interaction. This is a useful parameter for figuring out a specific predator-prey interaction in the wild. All the above mentioned factors will affect how well D. indicus performs as a predator in the field.

Lead (Pb) toxicity is a serious concern for edible crops, soil, and the environment. Therefore, an eco-friendly, cost-effective strategy is highly in demand to mitigate Pb toxicity in plants and provide health benefits for humans. This study aimed to explore the impact of exogenous sulfur (S) in mitigating Pb toxicity in mustard. Pb toxicity severely inhibited mustard growth, development, biomass yield, chlorophyll content, and photosynthetic attributes (Fv/Fm, Pi_ABS) in mustard. Interestingly, exogenous S considerably restored these morpho-physiological attributes in mustard. The concentration of S declined under Pb stress, and it was restored after exogenous S supplementation to roots and shoots, suggesting that S is actively involved in regulating Pb and S accumulation and homeostasis processes in mustard plants. Additionally, S supplementation in Pb-exposed plants induced the antioxidant activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), as well as the concentrations of glutathione (GSH) and phytochelatin (PC) in roots. Given the binding affinity of PC with toxic metals, the reduction of Pb in the aerial part may result from the vacuolar sequestration of Pb, mediated by elevated PC synthesis in the roots of mustard supplemented with S. These overall findings might be useful for oilseed crop breeders and farmers to apply S-amendments in Pb-free edible crop production.

Recognition of the fact that bacterial biofilm might contribute to the development of diseases has prompted a greater emphasis on identifying conditions, that could be linked to the biofilm formation. Microbial biofilms have raised significant concerns within the healthcare, medical, and food industries due to their inherent resistance to conventional antibiotics and cleaning methods, as well as their ability to firmly attach to surfaces, leading to enduring contamination concerns. A biofilm constitute a structural community of microorganisms, encased in a framework of extracellular polymeric substances. Biofilms pose a substantial challenge in the management of bacterial infections and stand as primary factors contribute to the enduring nature of these infections. Depending on their community microbiological makeup and the surrounding conditions, bacteria can create different types of single and multispecies biofilms. Over the past 20 years, interest in the study of bacterial biofilm formation has increased due to the exquisite intricacy of these multicellular communities and their role in infectious illnesses. Biofilms can form on almost any surface and can be advantageous or harmful, depending on the surface and how the community uses it. Extensive researchers have tackled the progressions in comprehending structural and functional variations, along with the roles that biofilms perform in illness and host–pathogen relationships.

The paper presents a detailed ecological investigation of mangroves (trees and palm) along Carigara Bay in Leyte, Philippines by comparing the diversity, vegetation structure, species composition, and indicator species among forest types (riverine and fringe) and zones (landward, middleward, and seaward/along water) as well as by examining their relationships with environmental variables. A total of 22 mangrove species, belonging to 12 families were documented wherein the most abundant was Sonneratia alba, followed by Nypa fruticans, then by Avicennia rumphiana. It was found that the diversity (Shannon-Wiener) of riverine mangroves (0.94 ± 0.07; 1.20 ± 0.04) was significantly higher than the fringe at the middleward and seaward/along the water (p < 0.001). In the fringe mangrove forests, the mangrove species Aegiceras corniculatum was associated with the middleward zone, and Camptostemon philippinensis, Aegiceras floridum, Rhizophora mucronata, Sonneratia alba, and Lumnitzera littorea were associated with the seaward zone, whereas landward zone of fringe and all the zones in riverine were generally associated by species with low to optimum salt tolerances such as Nypa fruticans, and Avicennia rumphiana as the most abundant. As well, a total of 14 mangroves have been identified as indicator species. Lastly, mangrove species can be generally classified as riverine and fringing based on the environmental factors explaining their distributions, and it has been found that soil porosity, water content, soil salinity, and distance from the sea or river’s edge were the most significant environmental factors that determine diversity patterns.

Phyllosphere-associated microorganisms must deal with various abiotic stresses such as high-low temperature, low nutrients, and ultraviolet (UV) radiation. These collective actions may trigger the generation of reactive oxygen species (ROS) and causes cellular damage. Cellular defense mechanisms such as morphological changes (size or appearance), production of photo-protectant compounds, and enhancement of antioxidant activities, all of which may contribute to the suppression of ROS and significantly increase survival rates under UV radiation. In this study, five UVB-resistant plant growth-promoting methylotrophs (Methylorubrum thiocyanatum (SD2), Rhodococcus kroppenstedtii (UK3), Methylorubrum populi (KD5), and Methylobacterium brachiatum (KD1 and SD3)) were investigated as adaptive strategies against UVB radiation. Exposure to UVB radiation revealed that methylotrophs changed their morphology to club or dumbbell shapes, and formed biofilm-like structures. Furthermore, Fourier transform-infrared spectroscopy (FTIR) and Gas chromatography-mass spectroscopy (GC–MS) analyses of the methanol-based intracellular extracts of methylotrophs revealed the presence of carotenoids, flavonoids, fatty acids, and antioxidants. Additionally, methylotrophs showed enhanced antioxidant activities such as superoxide dismutase, peroxidase, phenylalanine ammonia-lyase, and proline content with increased UVB exposure (1 -4 h). These findings demonstrate the ability and various adaptation strategies of methylotrophs to survive UVB exposure. These adaptive strategies may be one reason for the promotion of plant growth by methylotrophs under UVB radiation.

Antimicrobial resistance to pathogens is the cause of several million deaths globally. Therefore, the aim of the current study is to identify and isolate a new antimicrobial agent from Streptomyces sp. effective against several pathogenic microbes, including multidrug resistant (MDR) pathogens, using agriculture waste. Streptomyces isolate strain from the Egyptian soil was isolated, identified and grown on a local agricultural waste. The antimicrobial activity of the fermentation medium was tested against several pathogens using the well diffusion method. The most suitable fermentation and environmental factors for the maximum production of the antimicrobial bioactive compound was determined. Finally, the bioactive compound was purified, and characterized using several chromatographic and instrumental analyses. We identified Streptomyces bingchenggensis FHM200 isolate strain grown on peanut shells wastes. The maximum antimicrobial activity was attained by incubation with 2% (v/v) of the isolated strain (10⁵ spores / mL) at temperature range of 28–30℃ and pH range of 7.5 to 8 for 5 days, supplemented with potassium nitrate 0.2% (w/v) and dipotassium hydrogen phosphate (1 g/L). Finally, we managed to isolate and purify a novel bioactive compound; hexyl (2-hydroxyhexyl) phthalate, that possessed a promising antimicrobial activity against all tested pathogens with MIC of 70 µg/mL for Bacillus cereus ATCC 33018, 150 µg/mL for Aspergillus niger NRRL 326, and for MDR pathogens; 2500 µg/mL for methicillin resistance Staphylococcus aureus (MRSA) ATCC 43300, and 3000 µg/mL for both Escherichia coli 797, and Candida albicans 210. We concluded that hexyl (2-hydroxyhexyl) phthalate, isolated from Streptomyces bingchenggensis FHM200, possesses promising antimicrobial activity.

This study investigated the in vitro efficiency of Hypericum perforatum ethanolic extracts against Acanthamoeba castellani trophozoites. Cytotoxic effects of plant extract were determined. The protective action of plant extract against DNA damage was shown in the study, as well. The amoebicidial activity of H. perforatum ethanolic extracts was set on using in vitro ethanolic extraction (in quantities from 5, 10, 15, 20, 25, and 30 mg/ml). Different concentrations of H. perforatum ethanolic extracts and trophozoites were merged to determine the amoebicidial activity of the plant extract. Cytotoxicity was evaluated using a modified 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) assay. The effect of plant extract on hydroxyl radical-induced DNA damage was determined by electrophoresis on agarose gel. The growth of trophozoites terminated in H. perforatum ethanolic extracts with 50% inhibitory concentrations (IC50)/24 h for 30 mg/ml. The same extract solution had more vigorous amoebicidial activity on the trophozoites with IC50/72 h. Hypericum perforatum showed more substantial inhibitory effects on human cervical carcinoma cell lines (HELA) at concentrations of 5, 2.5, and 1.25 mg/mL at 72 h. The ethanolic extract of H. perforatum was more effective against Acanthamoeba and showed DNA protective activity. Hypericum perforatum extract has amoebicidial potential against A. castellani trophozoites, the causative agent of acanthamoebiasis. The results support that H. perforatum extract may be a nominee for developing an effective natural agent for treating acanthamoebiasis.