Length-to-weight and length-to-length ratios of six cavefish species from the Pearl River Basin,South China

Length-to-weight and length-to-length ratios were estimated for six cavefishes including Yunnanilus longibarbatus, Yunnanilus bailianensis, Yunnanilus jinxiensis, Oreonectes polystigmus, Paranemachilus pingguoensis, and Paranemachilus genilepis from the upper reaches of the Pearl River, Guangxi Province, China (between 106.26E, 23.14N and 111.42E, 24.85N). The fish were captured between May and October in 2018 and 2019 using trap nets (mesh size 7 mm) set in front of selected caves at 6:30–7:30 p.m. and were hauled out at 6:30–7:30 a.m. the next day. After removal, the fish were measured and weighed immediately to the nearest 0.1 cm and 0.1 g, respectively. The regression parameter r² was between .95 and .98. The total length-to-standard length ratios were also calculated with r² ≥ .98. This study should provide a useful reference for biological studies and biodiversity conservation of cavefish.     

Length-weight relationships of 10 fish species from the coastal waters of the East China Sea

The present study provides the length-weight relationships (LWRs) for 10 marine fish species collected from the coastal waters of the East China Sea by bottom trawl surveys. The open width of the sampling net was 40 m and the mesh size of the codend was 20 mm. Specimens were collected from November 2015 to November 2019 at seasonal intervals. The measurement accuracy of weight and length were 0.1 grams and 0.1 centimeters, respectively. This study provides new information of LWRs for nine species which have not yet been reported in FishBase. Also, this study updates the information of maximum length for two species.     

Length–weight relationships of seven fish species in the Yangtze River Estuary and its adjacent waters,Eastern China

The length–weight relationships (LWRs) for seven fish species belonging to five families in the Yangtze River Estuary and its adjacent waters are presented. Cynoglossus gracilis, Cynoglossus macrolepidotus, Ctenotrypauchen chinensis, Collichthys niveatus, Ophichthus apicalis and Erisphex potti were collected monthly in 2009 using trammel nets (the size of smaller mesh net was 1.5 m × 15 m × 4 panels with mesh sizes of 2.5, 3.4, 4.3 and 5.8 cm; the size of larger-mesh net was 2.4 m × 30 m × 4 panels with mesh sizes of 5.0, 6.0, 7.0 and 8.0 cm; soaking overnight). Lophiogobius ocellicauda were collected December in 2020 using shrimp trawl nets (mesh size 2.0 cm). The precision of measurement for the fish specimens is 0.1 cm total length and 0.1 g total weight. The estimated ranges of the parameters a and b for the seven fish species were from 0.0001 to 0.0289 and 2.718 to 3.541, respectively. Two new maximum total length were recorded for Ctenotrypauchen chinensis and Ophichthus apicalis.     

Length weight relationships of five marine fishes from the Bay of Bengal

Length weight relationships (LWR) of five marine fishes were estimated from the Bay of Bengal, Bangladesh. Fish samples were collected occasionally from fisher's catch with gill net (mesh size: 3 cm) during November 2019 to October 2020. Fishing was done overnight. Total length (0.1 cm) and body weight (0.01 g) of each individual were measured. We recorded maximum total length for P. maculatus (55.0 cm) and P. parmatus (39.0 cm).     

Intraspecific trait variation influences physiological performance and fitness in the South Africa shrub genus Protea (Proteaceae)

Background and AimsGlobal plant trait datasets commonly identify trait relationships that are interpreted to reflect fundamental trade-offs associated with plant strategies, but often these trait relationships are not identified when evaluating them at smaller taxonomic and spatial scales. In this study we evaluate trait relationships measured on individual plants for five widespread Protea species in South Africa to determine whether broad-scale patterns of structural trait (e.g. leaf area) and physiological trait (e.g. photosynthetic rates) relationships can be detected within natural populations, and if these traits are themselves related to plant fitness.MethodsWe evaluated the variance structure (i.e. the proportional intraspecific trait variation relative to among-species variation) for nine structural traits and six physiological traits measured in wild populations. We used a multivariate path model to evaluate the relationships between structural traits and physiological traits, and the relationship between these traits and plant size and reproductive effort.Key ResultsWhile intraspecific trait variation is relatively low for structural traits, it accounts for between 50 and 100 % of the variation in physiological traits. Furthermore, we identified few trait associations between any one structural trait and physiological trait, but multivariate regressions revealed clear associations between combinations of structural traits and physiological performance (R² = 0.37–0.64), and almost all traits had detectable associations with plant fitness.ConclusionsIntraspecific variation in structural traits leads to predictable differences in individual-level physiological performance in a multivariate framework, even though the relationship of any particular structural trait to physiological performance may be weak or undetectable. Furthermore, intraspecific variation in both structural and physiological traits leads to differences in plant size and fitness. These results demonstrate the importance of considering measurements of multivariate phenotypes on individual plants when evaluating trait relationships and how trait variation influences predictions of ecological and evolutionary outcomes.     

Toward insights on antimicrobial selectivity of host defense peptides via machine learning model interpretation

Host defense peptides are promising candidates for the development of novel antibiotics. To realize their therapeutic potential, high levels of target selectivity is essential. This study aims to identify factors governing selectivity via the use of the random forest algorithm for correlating peptide sequence information with their bioactivity data. Satisfactory predictive models were achieved from out-of-bag prediction that yielded accuracies and Matthew's correlation coefficients in excess of 0.80 and 0.57, respectively. Model interpretation through the use of variable importance metrics and partial dependence plots indicated that the selectivity was heavily influenced by the composition and distribution patterns of molecular charge and solubility related parameters. Furthermore, the three investigated bacterial target species (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) likely had a significant influence on how selectivity was realized as there appears to be a similar underlying selectivity mechanism on the basis of charge-solubility properties (i.e. but which is tailored according to the target in question).     

Inconsistent detection of extinction debts using different methods

The extinction debt, delayed species extinctions following landscape degradation, is a widely discussed concept. But a consensus about the prevalence of extinctions debts is hindered by a multiplicity of methods and a lack of comparisons among habitats. We applied three contrasting species–area relationship methods to test for plant community extinction debts in three habitats which had different degradation histories over the last century: calcareous grassland, heathland and woodland. These methods differ in their data requirements, with the first two using information on past and current habitat area alongside current species richness, whilst the last method also requires data on past species richness. The most data‐intensive, and hence arguably most reliable method, identified extinction debts across all habitats for specialist species, whilst the other methods did not. All methods detected an extinction debt in calcareous grassland, which had undergone the most severe degradation. We conclude that some methods failed to detect an extinction debt, particularly in habitats that have undergone moderate degradation. Data on past species numbers are required for the most reliable method; as such data are rare, extinction debts may be under‐reported.     

A review of mycotoxin biosynthetic pathways: associated genes and their expressions under the influence of climatic factors

Fungal contamination of agricultural commodities, particularly by mycotoxigenic fungi, represents an enormous concern for global food security in terms of feeding the world's growing population with sufficient and safe food. Not only do they reduce crop yield and quality, but they also produce substantial numbers of mycotoxins, which pose serious adverse health effects in human and animals. As the genome of most mycotoxigenic species have been sequenced, the gene clusters involved in the biosynthesis of agriculturally important mycotoxins including aflatoxins, fumonisins, ochratoxins, zearalenone and trichothecenes, have been largely identified and characterised, with their roles elucidated by researchers. This review provides a comprehensive overview of the current knowledge of genes involved in the biosynthetic pathways of mycotoxins. In addition, the influence of climatic factors including water, temperature and carbon dioxide on differential mycotoxin gene expressions have been highlighted. Overall, the relationship between the relative expression of key regulatory and structural genes under different environmental conditions is significantly correlated with mycotoxins production. This indicates that mycotoxin gene induction can be used as a reliable indicator or marker to monitor mycotoxin production pre-and-post harvest. Furthermore, current strategies to manage mycotoxin risks still require improvement. Thus, an accurate understanding of the molecular mechanisms of mycotoxin biosynthesis in mycotoxigenic species could help to develop an innovative, robust targeted control strategy. This could include the exploitation of novel compounds, which can inhibit biosynthetic genes, to minimise mycotoxin risks.     

动物对孢子植物的传播模式及进化意义

孢子植物物种多样性丰富, 是自然生态系统的重要组成部分。孢子植物的传播通常被认为主要依靠风、水、弹力等非生物媒介, 而动物的作用往往被忽略。本文主要概述了: (1)孢子植物对动物传播的适应: 一方面孢子植物可为动物提供食物、庇护所、繁殖场所等, 另一方面孢子植物也可产生视觉、嗅觉等方面的线索来吸引动物, 从而促进动物传播其繁殖体。(2)动物对孢子植物的传播模式: 包括体内传播(消化道和组织寄生)和体外传播两种, 这些模式都能对孢子植物繁殖体进行有效传播。由于动物间形态或生活习性的不同, 以致传播距离存在差异, 最短距离为0.1 cm, 最长距离可从北半球至南半球。(3)动物对孢子植物传播的生态与进化意义; 由于某些孢子植物繁殖体的结构特点或萌发的需求, 以致其繁殖体只能通过动物的传播才能得以定殖, 因此动物与孢子植物之间存在密不可分的关系。目前, 动物对孢子植物的传播研究主要是描述性的内容以及研究单方面的传播途径, 建议在今后的研究中考虑动物对孢子植物传播的有效性以及多途径同时传播对孢子植物定殖的影响, 同时应更加关注孢子植物和动物互惠关系的形成、维持机制及将来的进化趋势。     

Dynamics of solute/matric stress interactions with climate change abiotic factors on growth,gene expression and ochratoxin A production by Penicillium verrucosum on a wheat-based matrix

Penicillium verrucosum contaminates temperate cereals with ochratoxin A (OTA) during harvesting and storage. We examined the effect of temperature (25 vs 30 ^oC), CO₂ (400 vs 1000 ppm) and matric/solute stress (-2.8 vs -7.0 MPa) on (i) growth, (ii) key OTA biosynthetic genes and (iii) OTA production on a milled wheat substrate. Growth was generally faster under matric than solute stress at 25 ^oC, regardless of CO₂ concentrations. At 30 ^oC, growth of P. verrucosum was significantly reduced under solute stress in both CO₂ treatments, with no growth observed at -2.8 MPa (=0.98 water activity, a_w) and 1000 ppm CO₂. Overall, growth patterns under solute stress was slower in elevated CO₂ than under matric stress when compared with existing conditions. The otapksPV gene expression was increased under elevated CO₂ levels in matric stress treatments. There was fewer effects on the otanrpsPV biosynthetic gene. This pattern was paralleled with the production of OTA under these conditions. This suggest that P. verrucosum is able to actively grow and survive in both soil and on crop debris under three way interacting climate-related abiotic factors. This resilience suggests that they would still be able to pose an OTA contamination risk in temperate cereals post-harvest.