Water intake by the adult mayflyEpeorus ikanosis (Ephemeroptera: Heptageniidae) and its effect on their longevity

Water drinking habits during flight in adult mayflies ofEpeorus ikanonis Takahashi were observed and the effect of water intake on their longevity was examined. The study was carried out in a mountain stream in western Japan. Adult males collected a water droplet under the head capsule while alighting on the water surface and consumed it after moving to nearby riparian vegetation. The amount of water intake was experimentally estimated to be 9.7% of the bodyweight for males. Although females did not show the water drinking behavior in the field, they imbibed as much as 5.5% of the bodyweight of water in an experimental situation. Morphological observation of the mouthparts revealed that the water was drawn in through the pits at the base of the labrum. In the field caging experiment, males with a water supply had a substantially longer life span than those without. Increase in adult life span by drinking water was less marked in females. Multiple copulation was observed in both sexes during the experiment. The water drinking behavior of the males may closely relate to mating success through increased longevity. Variation in the longevity of adult mayflies was discussed with regard to the possibility of water intake. This paper forms part of a PhD thesis submitted to the Department of Zoology in Kyoto University (1990).     

ELF磁场对3T3细胞生长的影响及其机理的探讨

用细胞分析成像光盘记录系统测量了3T3细胞在某些ELF磁场和温度条件下生长周期的变化.实验结果表明,只有某些频率的ELF磁场才对细胞生长产生影响,磁场对细胞生长的影响还与培养细胞的生化环境有关.温度和ELF磁场都能影响细胞的生长.但二者的机理是不一样的,当撤除ELF磁场后,细胞在短时间内(2天以上)继续保持着ELF场对其生长的影响.而细胞生长周期能在短时间内(2天以内)随着温度的变化而变化.温度引起的细胞生长的变化可能与细胞内的各种生长因子、生物离子的活性有关.ELF磁场引起的细胞生长的变化可能与ELF磁场对细胞膜的影响有关,与细胞内细胞生长必不可少的生物离子(如Ca~(2+))的浓度有关.     

A transformer architecture for retention time prediction in liquid chromatography mass spectrometry-based proteomics

Accurate retention time (RT) prediction is important for spectral library-based analysis in data-independent acquisition mass spectrometry-based proteomics. The deep learning approach has demonstrated superior performance over traditional machine learning methods for this purpose. The transformer architecture is a recent development in deep learning that delivers state-of-the-art performance in many fields such as natural language processing, computer vision, and biology. We assess the performance of the transformer architecture for RT prediction using datasets from five deep learning models Prosit, DeepDIA, AutoRT, DeepPhospho, and AlphaPeptDeep. The experimental results on holdout datasets and independent datasets exhibit state-of-the-art performance of the transformer architecture. The software and evaluation datasets are publicly available for future development in the field.     

Embryonic and larval development of brown trout, Salmo trutta L.: exposure to trace metal mixtures in soft water

Freshly fertilized ova of brown trout, Salmo trutta L., were exposed to all possible mixtures of Al (6000 nmol 1¹), Cu (80 nmol 1⁻¹), Pb (50 nmol 1⁻¹) and Zn (300 nmol 1 ¹). In a separate experiment, newly hatched brown trout yolk-sac fry were exposed to Mn (1500 nmol 1⁻¹), Fe (2500 nmol 1 ¹), Ni (200 nmol 1⁻¹) or Cd (4 nmol 1 ¹), separately, and in mixtures with either Al or Cu. Both experiments were conducted in flowing, artificial softwater media nominally at pH 5.6 [Ca] 20 μmol 1 ¹ and 10° C.
Mortalities were high in fry subjected to treatments which contained both Al and Cu (31–72%), and to the Cu + Fe treatment (78%) compared with those from the other trace metal mixtures (0–22%). In all the treatments tested, fry exposed to trace metal mixtures containing Al and/or Cu had reduced whole body Ca, Na and K content, and seriously impaired skeletal calcification. Whole body Mg content was variable. In trace metal mixtures which contained Cu but not Al, the effects on fry survival and whole body mineral content were in general more deleterious than the corresponding mixtures but with Al present rather than Cu. The presence of Pb and/or Zn in mixtures with Al and/or Cu had a slight ameliorative effect in terms both of fry survival and whole body mineral content.     

Stream channel experiments on downstream movement of recently emerged trout, Salmo trutta L. and salmon, S. salar L.—I. Effect of four different water velocity treatments upon dispersal rate

Four experimental stream channels were used to study instantaneous downstream dispersal rates of young trout, Salmo trutta L., and salmon, S. salur L ., relative to four different water velocities.
Young salmon showed a high rate of dispersal at a low velocity of 7.5 cm s⁻¹ and lower rates at higher velocities of 25 to 70cm s⁻¹. Trout showed their lowest rate at 25cm s⁻¹ with a slightly higher rate at 7.5 cm s⁻¹ and increasingly higher rates at velocities in excess of 25 cm s⁻¹. These results are consistent with field observations on the velocity preferences of young trout and salmon.     

Two-phase species–time relationships in North American land birds

The species–time relationship (STR) is a macroecological pattern describing the increase in the observed species richness with the length of time censused. Understanding STRs is important for understanding the ecological processes underlying temporal turnover and species richness. However, accurate characterization of the STR has been hampered by the influence of sampling. I analysed STRs for 521 breeding bird survey communities. I used a model of sampling effects to demonstrate that the increase in richness was not due exclusively to sampling. I estimated the time scale at which ecological processes became dominant over sampling effects using a two‐phase model combining a sampling phase and either a power function or logarithmic ecological phase. These two‐phase models performed significantly better than sampling alone and better than simple power and logarithmic functions. Most community dynamics were dominated by ecological processes over scales <5 years. This technique provides an example of a rigorous, quantitative approach to separating sampling from ecological processes.     

Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees

This study examined the linkage between xylem vulnerability, stomatal response to leaf water potential (Ψ_L), and loss of leaf turgor in eight species of seasonally dry tropical forest trees. In order to maximize the potential variation in these traits species that exhibit a range of leaf habits and phenologies were selected. It was found that in all species stomatal conductance was responsive to Ψ_L over a narrow range of water potentials, and that Ψ_L inducing 50% stomatal closure was correlated with both the Ψ_L inducing a 20% loss of xylem hydraulic conductivity and leaf water potential at turgor loss in all species. In contrast, there was no correlation between the water potential causing a 50% loss of conductivity in the stem xylem, and the water potential at stomatal closure (Ψ_SC) amongst species. It was concluded that although both leaf and xylem characters are correlated with the response of stomata to Ψ_L, there is considerable flexibility in this linkage. The range of responses is discussed in terms of the differing leaf‐loss strategies exhibited by these species.     

Are the characeae able to indicate the origin of groundwater in former river channels?

The macroscopic algae Characeae are usually assumed to occur in waterbodies supplied by groundwater with low phosphate content, but the indicative value of the species is seldom defined in bibliography. Former braided channels of the Rhône river are supplied with groundwater originating from the main channel (seepage) or from hillslope aquifer. The aim of the present paper was to determine if it possible to use the Characeae as indicators of physicochemical characteristies of water in order to assess the origin of groundwater supplying former river channels. Four former braided channels of the Rhône River colonized by Characeae were investigated, and the physico-chemical characteristics of i) the channels, ii) the groundwater and iii) the river were measured over a period of several months. Species are arranged along a gradient of conductivity, alkalinity, ammonium and phosphate content of the water. Charophyte species can indicate the origin of groundwater, either seepage or hillslope nutrient-poor aquifer, and integrate both the average value of the chemical parameter, and their variations. C. hispida occurs in a nutrient-poor channel mainly supplied by highly calcareous groundwater coming from hillslope aquifer. Chara major has requirements close to those of C. hispida, but is more tolerant to periodic inputs of nutrients. C. vulgaris and N. syncarpa both tolerate mesotrophic waters originating from both hillslope aquifer and seepage, and C. globularis is associated to a channel mainly supplied by mesotrophic to eutrophic river seepage.     

Removal of caffeine in sewage by Pseudomonas putida: Implications for water pollution index

A strain of Pseudomonas putida (biotype A) capable of growing on caffeine (1,3,7-trimethylxanthine) was isolated from a domestic wastewater processing operation. It used caffeine as the sole carbon source with a mean growth rate constant (k) of 0.049 h^-1 (approximately 20 h per generation), whereas k for glucose utilization under similar incubation conditions was 0.31 (3.3 h per generation). The isolate contained at least two plasmids, and the increased expression of a 40 kDa protein was attributable to growth on caffeine. Degradation byproducts of caffeine metabolism by the bacterial isolate included other xanthine derivatives. The slow bacterial catabolism of caffeine in sewage has implications for the effectiveness of wastewater purification, re-use and disposal.The author is with the Laboratory for Molecular Ecology, Department of Environmental Analysis and Design, University of California at Irvine, Irvine, CA 92717-5150 U.S.A.