Sperm allocation in relation to male traits, female size, and copulation behaviour in freshwater crayfish species

Sperm competition is a well-recognised agent in the evolution of sperm and ejaculate structure, as well as variation in female quality. Models of the evolution of ejaculate expenditure predict that male body condition, female fecundity and the risk and intensity of sperm competition may be the ultimate factors shaping optimal ejaculate size. We investigated sperm allocation in Austropotamobius italicus, a freshwater crayfish exhibiting a coercive mating system and external fertilisation, in relation to male and female traits and copulation behaviour under laboratory conditions. We found that mating males were sensitive to female size and produced larger ejaculates when mating with larger females, which were more fecund in terms of number of eggs produced. We found no evidence for female egg production being sperm-limited, as the number of eggs was not dependent on male sperm expenditure. Copulation duration and number of ejaculations reliably predicted the amount of sperm transferred, and both these behavioural measures positively covaried with female body size. These results indicate that male freshwater crayfish can modulate their sperm expenditure in accordance with cues that indicate female fecundity. In addition, a novel finding that emerged from this study is the decrease in sperm expenditure with male body size, which may either suggest that large, old male crayfish are better able than small males to economise sperm at a given mating to perform multiple matings during a reproductive season, or that they experience senescence of their reproductive performance.     

First in vitro use of the phenylphosphate carboxylase enzyme in supercritical CO2 for the selective carboxylation of phenol to 4-hydroxybenzoic acid

A new biotechnological synthetic approach to 4-hydroxybenzoic acid is reported. Thauera aromatica cells produce the phenylphosphate carboxylase enzyme that selectively carboxylates phenylphosphate in the para position, without any formation of the ortho isomer. Here we show that the enzyme also works in supercritical carbon dioxide, opening a new technological solution to the recovery of the products that is a key problem when aqueous media are used. The enzyme shows an activity comparable with that shown under CO₂ pressure in aqueous media and does not require the presence of NaHCO₃.     

Production of biodiesel from macroalgae by supercritical CO2 extraction and thermochemical liquefaction

We compare two different techniques for the extraction of biodiesel from macroalgae: the thermochemical liquefaction and the extraction using supercritical carbon dioxide (sc-CO₂). The first allows to use wet material, while sc-CO₂ requires dry material and uses moderate temperature and pressure so that it can be useful for the extraction of thermolabile compounds which may decompose at the temperature at which thermal methos are carried out. In both cases the extracted oil was characterized quantitatively and qualitatively. The novelty of the work is that in the literature the use of macroalgae for the production of biodiesel has not so far been described, while they are used mainly as food or other purposes.     

气相色谱法观测本底大气中的甲烷和二氧化碳

根据世界气象组织全球大气监测（ＷＭＯ／ＧＡＷ）开展全球温室气体监测的要求，建立了气相色谱（ＧＣ）法甲烷和二氧化碳（ＣＨ４／ＣＯ２）连续观测系统，概述了该系统厍拿大大气环境局（ＡＥＳ）５个月的组装调试，以及在中国大气本底基准台（ＣＧＡＷＢＯ＿一年多时间里的业务运行和标定情况，且装调试和运动标定，与红餐吸收（ＮＤＩＲ）法，气瓶采样－实验室分析（ＦＬＡＳＫ）法数据，以及与上其它台站观测资料的对比结果表明     

Poly(hydroxyalkanoates) from fluorescent pseudomonads in retrospect and prospect

Poly[(R)-3-hydroxyalkanoates] (PHAs) are biopolymers stored by bacteria, which are currently receiving much attention because of their potential as renewable and biodegradable plastics. Most well-known representatives are poly[(R)-3-hydroxybutyrate] and its copolymers with 3-hydroxyvalerate, which have been commercialized under the trademark Biopol. In addition to these rigid materials, the elastomeric medium-chain length PHAs (mcl-PHAs) produced by fluorescent Pseudomonads are now emerging. The present review aims to survey the important developments concerning research and application prospects of mcl-PHAs.     

Sublethal detergent concentrations increase metabolization of recalcitrant polyphosphonates by the cyanobacterium Spirulina platensis

As a consequence of increasing industrial applications, thousand tons of polyphosphonates are introduced every year into the environment. The inherent stability of the C–P bond results in a prolonged half-life. Moreover, low uptake rates limit further their microbial metabolization. To assess whether low detergent concentrations were able to increase polyphosphonate utilization by the cyanobacterium Spirulina platensis, tolerance limits to the exposure to various detergents were determined by measuring the growth rate in the presence of graded levels below the critical micellar concentration. Then, the amount of hexamethylenediamine-N,N,N′,N′-tetrakis(methylphosphonic acid) that is metabolized in the absence or in the presence of sublethal detergent concentrations was quantified by ³¹P NMR analysis on either P-starved or P-fed cyanobacterial cultures. The strain tolerated the presence of detergents in the order: nonionic > anionic > cationic. When added to the culture medium at the highest concentrations showing no detrimental effects upon cell viability, detergents either improved or decreased polyphosphonate utilization, the anionic sodium dodecyl sulfate being the most beneficial. Metabolization was not lower in P-fed cells—a result that strengthens the possibility of using, in the future, this strain for bioremediation purposes.     

The interactive effects of procedural justice and exchange ideology on supervisor-rated commitment

Matched data collected from 143 employees and their immediate supervisors of a private sector organization indicated that employee perceptions of procedural justice were only related to supervisor-rated affective commitment among employees with a strong exchange ideology. That is, individuals motivated by a fair exchange exhibited fewer affective commitment behaviors when they viewed the environment as unfair than when they perceived it to be fair. Individuals comparatively indifferent to a fair exchange did not alter their affective commitment behaviors regardless of the level of perceived environmental fairness. These results illustrate the importance of considering individual differences in exchange ideology when attempting to alter the work environment for the purpose of increasing commitment. Implications for research and management practice are presented. Copyright © 2001 John Wiley & Sons, Ltd.     

Spawning patterns in the leopard grouper, <Emphasis Type="Italic">Mycteroperca rosacea</Emphasis>, in comparison with other aggregating groupers

We documented the spawning patterns of the leopard grouper, Mycteroperca rosacea, from April to June 2005 in the central Gulf of California, Mexico to draw comparisons with other aggregate-spawning groupers and provide information useful for management of their fishery. Adults formed spawning aggregations of 150 to >700 individuals at specific sites, and spawning occurred daily at these sites from late April through early June. Courtship occurred throughout the day, but spawning was restricted to the evening hours. Adults spawned in groups of 6–40 fish, and pair-spawning was not observed. The group-spawning behavior of adults and the gonosomatic indices of mature males (maximum = 7.2%) suggest that sperm competition was present. The site-specificity of leopard grouper spawning aggregations and diel spawning period were typical of most aggregating groupers, and the size and structure of these aggregations was similar to other species in the genus Mycteroperca. Leopard grouper behavior patterns were unusual in that spawning aggregations persisted for extended periods, spawning was not synchronized with the lunar cycle, and adults aggregated during non-spawning periods. The extensive duration and site-specificity of spawning aggregations and the propensity of M. rosacea to form aggregations year-round increases the vulnerability of the species to overfishing. Policies that limit harvest from these aggregations are needed to improve the management of leopard grouper fisheries in the Gulf of California.     

Discriminating among organizational politics,justice, and support

The discriminant validity of perceptions of organizational politics, organizational support, and procedural and distributive justice was examined as the distinctions between these variables have been blurred in past research. Results from a sample of 418 full‐time employees provided evidence of discriminant validity for these variables. First, structural equation modelling was used to isolate the best structural representation of these four variables. Then, six theoretically relevant predictors (i.e., leader–member exchange, centralization, formalization, co‐worker cooperation, role conflict, and locus of control) were examined in an effort to provide further conceptual separation. Five of the six antecedents distinguished among politics, justice, and support. Suggestions for additional research that can shed light on the distinctions and similarities of these variables are offered based on the results of this study. Copyright © 2001 John Wiley & Sons, Ltd.     

Saharan dust clouds and human health in the English-speaking Caribbean: what we know and don’t know

Dust clouds travel across the Atlantic to the Americas and the Caribbean Islands. This long-range transport of dust leads to clouds that are enriched with small particles less than 10 microm aerodynamic diameter (PM10) which can reach human airways. The dust clouds also bring pollen, microbes, insects and chemicals, all of which could potentially have a negative impact on human health. This has led to a small number of retrospective studies being conducted on the islands of Barbados and Trinidad to look at possible associations between dust cover and acute asthma admissions to Emergency Rooms. The results have been conflicting. This review examines these studies, offers possible explanations for the differences in results, and suggests that there is a need for a prospective Caribbean-wide study to assess fully any relationship between African dust clouds and human respiratory and cardiovascular diseases.