Loss of Key Riparian Plant Species Impacts Stream Ecosystem Functioning

Ecosystems - Leaf litter of alder (Alnus glutinosa) is a key resource to detrital stream food webs. Due to its high quality and palatability, it is readily colonised by microorganisms and consumed...     

Impact of manipulation of glycerol/diol dehydratase activity on intestinal microbiota ecology and metabolism

Glycerol/diol dehydratases (GDH) are enzymes that catalyse the production of propionate from 1,2-propanediol, and acrolein from glycerol. Acrolein reacts with dietary carcinogenic heterocyclic amines (HCA), reducing HCA mutagenicity, but is itself also an antimicrobial agent and toxicant. Gut microbial GDH activity has been suggested as an endogenous acrolein source; however, there is limited information on the potential of the intestinal microbiota to have GDH activity, and what impact it can have on the intestinal ecosystem and host health. We hypothesized that GDH activity of gut microbiota is determined by the abundance and distribution of GDH-active taxa and can be enhanced by supplementation of the GDH active Anaerobutyricum hallii, and tested this hypothesis combining quantitative profiling of gdh, model batch fermentations, microbiota manipulation, and kinetic modelling of acrolein formation. Our results suggest that GDH activity is a common trait of intestinal microbiota shared by a few taxa, which was dependent on overall gdh abundance. Anaerobutyricum hallii was identified as a key taxon in GDH metabolism, and its supplementation increased the rate of GDH activity and acrolein release, which enhanced the transformation of HCA and reduced fermentation activity. The findings of this first systematic study on acrolein release by intestinal microbiota indicate that dietary and microbial modulation might impact GDH activity, which may influence host health.     

Volatiles from Marina neglecta: Biocide effect on insect vectors of tropical diseases in Southern Mexico

Preventive measures based in the control of insect vectors are considered as the best choice to decrease the incidence of insect-borne diseases. Herein we report on the volatile content of the leaf essential oils from Marina neglecta, a medicinal plant distributed in the tropical regions of southern Mexico. In order to investigate the chemical variation of the essential oils, a volatile screening was performed during the four seasons of the years 2016–2019. Simultaneously, their biological activity was tested on distinct life stages of Meccus pallidipennis, M. bassolsae, Aedes aegypti and A. albopictus. Essential oils were mainly constituted of β-pinene (>30%) β-caryophyllene (>25%) and germacrene D (>13%). Dorsal-abdomen application of essential oils on triatomines, revealed an efficient LC₅₀ for nymphs of the stages I to III (4 µg/insect), nymphs of the stages IV to V (5–6 µg/insect), and adults (7–8 µg/insect). The LT₅₀ for the stages I to III was between 6 and 8 h, whereas that for the stages IV to V and adults oscillated between 12 and 16 h and 22 to 26 h, respectively. Fumigation experiments performed on nymph V, demonstrated that 300 µg L^?1 air produced 100% mortality after 72 h post-treatment. Among tested volatiles, β-pinene and β-caryophyllene produced a comparable mortality rate (p < 0.01) than that of essential oils in the stages assayed. Essential oils showed strong larvicidal (LC₅₀, 24–36 µg mL^?1) and adulticidal (35–48 µg mL^?1) activities in mosquito species with an LT₅₀ of 4.5 h and 25–35 min, respectively. The evaluation of β-pinene produced a significant mortality rate (p < 0.01) in larvae whereas germacrene D was the most effective volatile (p < 0.01) against adults of both mosquito species. According to our results, β-pinene was the most effective volatile against the four insect species evaluated and its effect was comparable to that of the essential oil.     

Initiation, long-term cryopreservation, and recovery of Abies alba Mill. embryogenic cell lines

Somatic embryogenesis of Abies alba (Mill.) has significant potential to become an effective method for vegetative propagation of this species. To induce somatic embryogenesis in A. alba, the influence of the mother tree, sampling dates, and cold treatment storage of cones were examined. The initiation frequencies ranged from 1.7% to 16.6%. The sampling date and cone storage, but not the mother tree, had a significant effect on the initiation of embryogenic cultures. Storage of embryogenic cell lines was tested through cryopreservation for 6 yr. Four out of 12 cryostored embryogenic cell lines recovered, and the regeneration of cotyledonary embryos was obtained with two cell lines. The ability of embryogenic cell masses to produce somatic embryos and the mean number of cotyledonary embryos were higher when the maturation protocol was based on embryogenic suspensions dispersed on filter paper. The properly developed germinants were obtained only from maturation media where 32 μM abscisic acid was used, being 16.2% when polyethylene glycol (PEG) was not present and 1.8% when supplemented with 10% (w/v) PEG, respectively. The present study provides evidence that it is possible to cryopreserve A. alba embryogenic cultures while maintaining their maturing ability for the lengthy period (6 yr) needed for progeny testing of field-grown trees. Therefore, our findings are important for further studies and advanced breeding work of the species; however, the conversion of germinants into ex vitro conditions still remains a significant challenge.     

cis-Jasmone indirect action on egg parasitoids (Hymenoptera: Scelionidae) and its application in biological control of soybean stink bugs (Hemiptera: Pentatomidae)

In many plants, the secondary metabolite cis-jasmone activates the metabolic pathway that produces volatile organic compounds attractive to natural enemies and, sometimes, repellent to herbivores. Previous studies indicate that the feeding damage caused by the herbivore Euschistus heros or the exogenous application of cis-jasmone in soybean plants induces the release of herbivore-induced plant volatiles (HIPVs) with a similar chemical profile and these compounds can attract the stink bug egg parasitoid Telenomus podisi (Scelionidae). Herein we tested in field conditions the effect of exogenous application of cis-jasmone in soybean plants on the parasitoid and stink bug community and on stink bug egg parasitism. In two areas, one within a soybean and another within a Crotalaria matrix, we randomly distributed 2 m² plots, with soybean plants induced (treatment, n = 5) or not induced by cis-jasmone (control, n = 5) in the field. We sampled the parasitoid community weekly with yellow sticky traps (n = 3/plot) and monitored parasitism with sentinel eggs of E. heros (n = 150/plot). We also monitored the population of stink bugs weekly, by sampling each plot with shake-cloth technique. The abundance of Scelionidae was highest overall and also in treated plots during the first four weeks in the area with a soybean matrix, but decreased thereafter. The richness of parasitoid families was similar between treatment and control plots in the area with a soybean matrix, but higher in control plots in the area with a Crotalaria matrix. Evenness was higher in control plots in the area with soybean matrix, whereas the reverse occurred in the area with a Crotalaria matrix. Results suggest that treatment with cis-jasmone effectively attracted and enhanced the population of scelionid parasitoids, but had no effect on the occurrence and intensity of parasitism and in the number of stink bugs.     

An electromyographic analysis of two handwriting grasp patterns

BackgroundHandwriting is a fundamental skill needed for the development of daily-life activities during lifetime and can be performed using different forms to hold the writing object. In this study, we monitored the sEMG activity of trapezius, biceps brachii, extensor carpi radialis brevis and flexor digitorum superficialis during a handwriting task with two groups of subjects using different grasp patterns.Subjects and methodsTwenty-four university students (thirteen males and eleven females; mean age of 22.04 ± 2.8 years) were included in this study. We randomly invited 12 subjects that used the Dynamic Tripod grasp and 12 subjects that used the Static Tripod grasp.ResultsThe static tripod group showed statistically significant changes in the sEMG activity of trapezium and biceps brachii muscles during handwriting when compared to dynamic tripod group’s subjects. No significant differences were found in extensor carpi radialis brevis and flexor digitorum superficialis activities among the two groups.ConclusionThe findings in this study suggest an increased activity of proximal muscles among subjects using a transitional grasp, indicating potential higher energy expenditure and muscular harm with the maintenance of this motor pattern in handwriting tasks, especially during the progression in academic life.     

Multi-channel electromyography during maximal isometric and dynamic contractions

Motor unit behavior differs between contraction types at submaximal contraction levels, however is challenging to study during maximal voluntary contractions (MVCs). With multi-channel surface electromyography (sEMG), mean physiological characteristics of the active motor units can be extracted. Two 8-electrode sEMG arrays were attached on biceps brachii muscle (one on each head) to examine behavior of sEMG variables during isometric, eccentric and concentric MVCs of elbow flexors in 36 volunteers.On average, isometric (364 ± 88 N) and eccentric (353 ± 74 N) MVCs were higher than concentric (290 ± 73 N) MVC (p < 0.001). Mean muscle fiber conduction velocity (CV) was highest during eccentric MVC (4.42 ± 0.49 m/s) than concentric (4.25 ± 0.49 m/s, p < 0.01) and isometric (4.14 ± 0.45 m/s, p < 0.001) MVCs. Furthermore, eccentric MVC showed lower sEMG amplitude at the largest elbow joint angles (120–170°) and higher CV at the smallest (70–150°) elbow joint angles (p < 0.05–0.001) than concentric MVC.The differences in CV and sEMG amplitude between the MVCs suggest that the control strategy of motor units differs between the contraction types during MVCs, and is dependent on the muscle length between the dynamic MVCs.     

Impiego delle sezioni di coleoptile di alcune varietà italiane di frumento nel dosaggio biologico di sostanze promotrici ed inibitrici della crescita

Abstract

Growth response of coleoptile sections from four Italian cultivars of wheat to some growth regulators.—The following Italian wheat varieties were used to obtain the coleoptile sections used throughout the experiments: Funo, S. Pastore, Abbondanza, Generoso.

The growth substances tested were Indolacetic acid (IAA), Abscisic acid (ABA), Kinetin and Gibberellic acid.

The colcoptile response of each variety was tested with three different concentrations for each growth regulator in combination with two sucrose concentrations and three different pH levels.

The experiments indicated that the coleoptiles from the variety « Funo » react linearly to incresing IAA and ABA concentration resulting the best one to be used in this bioassay.     

Sulla ecologia della “Saxifraga Cernua L.„ al limite meridionale dell'area geografica

Riassunto

L'A. illustra la morfologia e l'anatomia di Solenostemma Argel con particolare considerazione dei caratteri del legno secondario in rapporto all'abito sempreverde della pianta.     

Glucose Accelerates Copper- and Ceruloplasmin-induced Oxidation of Low-density Lipoprotein and Whole Serum

Glucose at pathophysiological concentrations was able to accelerate copper-induced oxidation of isolated low-density lipoprotein (LDL) and whole serum. The efficiency of glucose was favored under the following circumstances: (a) when LDL oxidation was induced by low copper concentration, (b) when LDL was partly oxidized, i.e. enriched with lipid peroxides. The glucose derivative methyl- &#102 - d -glucoside was ineffective on Cu 2+ -induced LDL oxidation, pointing out the essential role of the reactivity of the aldehydic carbon for the pro-oxidative effect. When LDL oxidation was induced by a peroxyl radical generator, as a model of transition metal independent oxidation, glucose was ineffective. Glucose was found to stimulate oxidation of LDL induced by ceruloplasmin, the major copper-containing protein of human plasma. Thus, glucose accelerated oxidation of LDL induced by both free and protein bound copper. Considering the requirement for catalytically active copper and for the aldehydic carbon, the pro-oxidative effect of glucose is likely to depend on the increased availability of Cu + ; this is more efficient in decomposing lipid peroxide than Cu 2+ , accounting for acceleration of LDL oxidation. The possible biological relevance of our work is supported by the finding that glucose was able to accelerate oxidation of whole serum, which was assessed by monitoring low-level chemiluminescence associated with lipid peroxidation.