Longidorus israelensis sp. n. (Nematoda : Dorylaimoidea), a parasite of carrot in Israel

#Longidorus israelensis sp. n., espèce parthénogénétique associée à des dégâts sur carotte en Israël, est décrite. Cette espèce est caractérisée par une grande longueur du corps (7,1-9,1 mm), une région labiale légèrement en relief et aplatie frontalement, des poches amphidiennes non bilobées, un long odontostyle (125-135 micromètres) et une queue courte, sub-hémisphérique (36-46 micromètres). Elle présente également une disposition inhabituelle des noyaux des glandes oesophagiennes. Les carottes attaquées par #L. israelensis sp. n. voient la croissance de leurs racines stoppée, le départ de racines secondaires et l'apparition de renflements à l'extrémité des racines. Il en résulte des carottes déformées et divisées en pluseiurs parties. Le nématode est généralement rencontré à des profondeurs du sol variant de 20 à 40 cm mais il peut migrer jusqu'à 40-100 cm de profondeur de façon à survivre pendant la période estivale chaude et sèche. (Résumé d'auteur

Spontaneous fluctuations in liver biochemistries in patients with compensated NASH cirrhosis: Implications for drug hepatotoxicity monitoring

Introduction: Patients with cirrhosis may have spontaneous fluctuations in liver enzymes, which may confound detection of drug-induced liver injury (DILI), but these fluctuations have not been described. Objective: We sought to quantify spontaneous liver enzyme abnormalities in patients with cirrhosis due to nonalcoholic steatohepatitis (NASH) enrolled in clinical trials. Methods: We examined the laboratory values of patients with compensated cirrhosis randomized to placebo in two clinical trials for NASH. Patients in one study were followed every 13 weeks up to week 57; patients in the other study were followed every 4 weeks up to week 120. Results: In total, 53 and 85 patients were randomized to placebo in the trials. Baseline alanine aminotransferase (ALT) was greater than the laboratory upper limit of normal (ULN) in 53% and 49% of participants, aspartate aminotransferase (AST) was > ULN in 49% and 59%, alkaline phosphatase was > ULN in 36% and 27%, and bilirubin was >ULN in 13% and 19%. During follow-up, ALT increased to 2× baseline in 8% and 15%, AST increased to 2× baseline in 6% and 21%, and bilirubin increased to 2× baseline in 9% and 18%. Alkaline phosphatase did not increase to 2× baseline for any patient. The maximum ALT was 3× ULN in 9% and 12%. ALT increased to 3× baseline in three patients and to 5× ULN in two patients. No patients had elevations consistent with Hy's law. The maximum ALT for patients with abnormal baseline values was higher [median 48 U/L (range 34-299) and 56 U/L (47-85)] than for those with normal baseline values [median 26.5 U/L (range 18-33) and 29 U/L (25.5-30.5)] in both studies, respectively, with p < 0.001. Conclusion: Spontaneous liver enzyme abnormalities are common in patients with NASH cirrhosis in clinical trials, and these abnormalities rarely met criteria for DILI suspicion. Further work to better define these abnormalities and continued vigilance to detect DILI in this population is needed

Anoxia begets anoxia: a positive feedback to the deoxygenation of temperate lakes

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1–126,909 ha), maximum depth (6–370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate change and other anthropogenic pressures driving the development of anoxia in lakes around the world

Causal networks of phytoplankton diversity and biomass are modulated by environmental context

Untangling causal links and feedbacks among biodiversity, ecosystem functioning, and environmental factors is challenging due to their complex and context-dependent interactions (e.g., a nutrient-dependent relationship between diversity and biomass). Consequently, studies that only consider separable, unidirectional effects can produce divergent conclusions and equivocal ecological implications. To address this complexity, we use empirical dynamic modeling to assemble causal networks for 19 natural aquatic ecosystems (N24◦~N58◦) and quantified strengths of feedbacks among phytoplankton diversity, phytoplankton biomass, and environmental factors. Through a cross-system comparison, we identify macroecological patterns; in more diverse, oligotrophic ecosystems, biodiversity effects are more important than environmental effects (nutrients and temperature) as drivers of biomass. Furthermore, feedback strengths vary with productivity. In warm, productive systems, strong nitrate-mediated feedbacks usually prevail, whereas there are strong, phosphate-mediated feedbacks in cold, less productive systems. Our findings, based on recovered feedbacks, highlight the importance of a network view in future ecosystem management