Lower lethal temperatures for fourteen non-native fishes in Florida

Synopsis The most important factor affecting the potential range of 14 non-native fishes in Florida appears to be their lack of tolerance to low temperatures. In this study, temperatures associated with reduction in feeding, cessation of feeding, loss of equilibrium and death were identified by decreasing water temperature 1°C day^–1. Fishes tested and their mean lower lethal temperatures were: Astronotus ocellatus (12.9°C), Belonesox belizanus (9.7°C), Cichlasoma bimaculatum (8.9°C), C. cyanoguttatum (5.0°C), C. meeki (10.3°C), C. octofasciatum (8.0°C), C. trimaculatum (10.9°C), Clarias batrachus (9.8°C), Hemichromis bimaculatus (9.5°C), Hypostomus sp. (11.2°C), Tilapia aurea (6.2°C), T. mariae (11.2°C), T. melanotheron (10.3°C) and T. mossambica (9.5°C). These data indicate that temperature is less limiting for these fishes in Florida than was previously recognized.Contribution Number 18, Non-Native Fish Research Laboratory, Florida Game and Fresh Water Fish Commmission, 801 N. W. 40th Street, Boca Raton, FL 33431, U.S.A.     

Tissue specific variation of C-glycosylflavone patterns in oat leaves as influenced by the environment

A comparison is made between the flavone patterns accumulating in epidermal tissues and in the mesophyll of oat primary leaves grown in a phytotron and under field conditions. In developing leaves cultivated under standard conditions, varying patterns of two vitexin-derived O-rhamnosides and of one isovitexin O-arabinoside are produced in the basal region as the result of basal meristem activity. These patterns are tissue specific and differ quantitatively in the epidermis and the mesophyll. During the course of subsequent growth and differentiation, this pattern is constant as the compounds are moved upwards due to basipetal leaf growth. In comparison, the flavone patterns generated in the basal section of leaves grown in the field do not vary significantly. There is the additional accumulation of isoorientin O-arabinoside. Again flavone patterns are tissue specific, but in contrast to standard growth they are modified characteristically in those leaf tissues which are already morphologically differentiated. It is possible that the isovitexin moiety of the O-arabinoside is oxidized to the corresponding isoorientin derivative in the mesophyll. Moreover, field-grown leaves show a two-fold increase in flavone content in each leaf epidermis and a six-fold increase in the mesophyll when compared to the corresponding tissues of phytotron-grown leaves.     

Population ecology of a Stratiotes aloides l. stand in a riverside lagoon in N. Sweden

A stand of Stratiotes aloides L. in a riverside lagoon, Abborravan on the Vindelälven river in N Sweden, was studied for 3 years (1975–1977). The stand was vegetative, at all times submerged and therefore never flowering. On average each plant produced 3 adventitious roots and 40 leaves. One or two turions were also produced each year, together with stolons and associated offsets. At the beginning of June 1977 the population density was 42 plants/m² and the biomass was 290 kg/ha (dry wt. basis). At the end of September that year the respective values were 90/m² and 756 kg/ha. The dry wt./fresh wt. ratio of the biomass changed little during that period, from 6.4 to 6.5%. These and other results are compared with the respective data for Stratiotes stands in Central European lakes. In Abborravan Stratiotes seems well-adapted to survive the prevailing, hard, winter conditions. Freezing in situ is quite normal and is only lethal if the overwintering basal rosettes become frozen solid. The turions are quite frost-hardy.     

Can soil Chytridiomycota survive and grow in different osmotic potentials?

Twenty isolates from soil in the orders Spizellomycetales, Blastocladiales and Chytridiales (Chytridiomycota) grew on complex solid media supplemented with 10 g l⁻¹ sodium chloride. In a synthetic liquid medium, 4.4 g l⁻¹ sodium chloride strongly inhibited growth in three of the five isolates, possibly because of the effect of the ions or osmolarity of the solution. The maximum concentration for growth in synthetic liquid medium with different osmotic potentials using polyethylene glycol (PEG) varied considerably amongst the isolates. Three patterns of growth with increasing concentrations of PEG were evident among isolates within the genus Rhizophydium. Up to the concentration where growth ceased, the dry weight of each isolate either decreased, remained constant, or in one case, increased. Most of the fungi survived when incubated at room temperature for 7 d in complex liquid media supplemented with 35 g l⁻¹ sodium chloride or 300 g l⁻¹ PEG. These data indicate that soil Chytridiomycota can survive various osmotic potentials that may occur during the wetting and drying phases in soils.     

Fitness costs of worker specialization for ant societies

Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony''s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies.     

Non-aerated cultivation ofHalobacterium cutirubrum and its effect on cellular squalenes

Summary Halobacterium cutirubrum was successfully cultivated under aerobic and microaerobic conditions. The early stationary phase of growth was obtained at 2.2 days and 45–55 days for aerated and non-aerated cultures, respectively. The dry cell yields were 0.7–1.2 gm/l in all preparations grown to early stationary growth phase. The cellular ratio of squalene to dihydro- and tetra-hydrosqualene decreased proportionately with decreased aeration rates.     

A highly selective and sensitive boronic acid-based sensor for detecting Pd2+ ion under mild conditions

Herein, a boronic acid-based sensor was reported selectively to recognize Pd²⁺ ion. The fluorescence intensity increased 36-fold after sensor binding with 2.47 × 10⁻⁵ M of Pd²⁺ ion. It was carried out in the 99% aqueous solution for binding tests, indicating sensor having good water solubility. In addition, it is discernible that Pd²⁺ ion turned on the blue fluorescence of sensor under a UV–lamp (365 nm), while other ions (Ag⁺, Al³⁺, Ba²⁺, Ca²⁺, Cr²⁺, Cd²⁺, Co²⁺, Cs²⁺, Cu²⁺, Fe²⁺, Fe³⁺, K⁺, Li⁺, Mg²⁺, Mn²⁺, Na⁺, Ni²⁺ and Zn²⁺) did not show the similar change. Furthermore, sensor has a low limit of detection (38 nM) and high selectivity, which exhibits the potential for the development of Pd²⁺ recognition in practical environments.     

Leaf osmotic potential decrease: a possible cause of mortality of greenhouse whitefly eggs

Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) white eggs were detached from the leaf and exposed to a range of osmotic concentrations (between −0.4 and −2.2 MPa) in controlled conditions. Eggs were able to hatch in the low and medium solute concentrations. In the higher concentrations, eclosion was delayed and significant mortality due to egg desiccation was observed. These results indicate leaf osmotic potential is a plant characteristic that affects greenhouse whitefly survivorship. Therefore leaf osmotic potential should be considered when evaluating greenhouse whitefly resistance.     

不同病情急性缺血性脑卒中患者血清过氧化还原蛋白1、钙调蛋白、触珠蛋白水平与预后的关系分析

摘要 目的：探讨不同病情急性缺血性脑卒中（AIS）患者血清过氧化还原蛋白1(PRDX1)、钙调蛋白(CAM)、触珠蛋白(HPT)水平与预后的关系。方法：收集2018年4月~2019年4月期间本院收治的127例AIS患者为研究对象,根据患者的病情分为轻度组(39例)、中度组(48例)、重度组(40例),根据患者的改良Rankin 量表( mRS)评分将患者分为预后良好组(73例)和预后不良组(54例),另选同期在我院进行健康检查的健康受试者50例为对照组。对比所有受试者PRDX1、CAM、HPT水平。对比不同预后患者的一般资料、PRDX1、CAM、HPT水平。分析PRDX1、CAM、HPT与NIHSS评分、mRS评分的关系。以多因素Logistic回归分析AIS患者预后的影响因素。结果：轻度组、中度组、中度组的PRDX1、CAM、HPT水平均高于对照组,且随着患者的病情加重,PRDX1、CAM、HPT水平依次升高,差异均有统计学意义(P<0.05)。预后不良组患者的年龄、PRDX1、CAM、HPT均高于预后良好组(P<0.05)。经Pearson检验,AIS患者的PRDX1、CAM、HPT与NIHSS、mRS评分均呈正相关(P<0.05)。经多因素Logistic回归分析可得,年龄较高、PRDX1水平升高、CAM水平升高、HPT水平升高是AIS患者预后不良的危险因素(P<0.05)。结论：AIS患者的PRDX1、CAM、HPT水平异常升高,且与其病情及预后呈现明显的相关性,年龄、PRDX1、CAM、HPT是患者预后的影响因素,对于病情的评估、预后的判断有一定的临床指导价值。