热休克诱导鳙鱼四倍体的研究

采用热休克法研究了诱导鳙鱼四倍体的可能性和处理条件。结果表明:1)恰好在卵子开始第一次卵裂前用39—42℃水浴处理1—3分钟,可获得较高频率的四倍体;2)开始处理的时间至关重要,提前或推迟处理导致几乎全部死亡或四倍体频率大大下阵;3)热休克组的孵化率显著下降,畸形率明显升高;4)含高频率四倍体的热休克组的细胞分裂和胚胎发育延迟。     

Photosynthesis and photoprotective strategies in Laurus nobilis L. and Quercus ilex L. under summer drought and winter cold

Abstract

Photosynthesis and photoprotective mechanisms were investigated in the field on Laurus nobilis L. and Quercus ilex L. leaves exposed to summer drought (July) and winter cold (February) conditions compared with no-stress conditions (May). In July, net photosynthetic rate (A) and stomatal conductance (g _s) decreased significantly compared with May in both species; conversely the highest ETR/A ratio and no difference in non-photochemical quenching (NPQ) was observed. In February A, g _s and ETR/A declined compared with May but the highest NPQ were found in both species. Our data suggest that during summer, an increase of photochemical alternative pathways to carbon reduction, were able to effectively protect the photosynthetic apparatus under drought. In winter, the thermal dissipation of excess absorbed light constitutes the main safety valve for the photosynthetic apparatus.     

Purification and Some properties of Endo-β-1,6-Glucanase from Acinetobacter sp.

A kind of endo-β-1, 6-glucanase has been purified from the culture filtrate of Acinetobacter sp. grown in the medium containing baker’s yeast cells as a carbon source. A 100-fold purified preparation was obtained by DEAE-Sephadex A–50 column chromatography. The enzyme hydrolyzed pustulan giving a series of gentio-oligosaccharides and glucose. Gentiotriose and gentiotetraose were hydrolyzed by this enzyme yielding glucose and gentiobiose, and glucose, gentiobiose and gentiotriose, respectively. Gentiobiose was not hydrolyzed. Baker’s yeast glucans obtained from the isolated cell walls were also hydrolyzed by this enzyme giving a series of oligosaccharides and glucose. From the action patterns on these carbohydrates, we concluded the present enzyme being endo-β-1, 6-glucanase.     

Laurus nobilis leaf extract controls inflammation by suppressing NLRP3 inflammasome activation

Laurus nobilis Linn. (Lauraceae), commonly known as Bay, has been used as a traditional medicine in the Mediterranean and Europe to treat diverse immunological disorders. Although the effects of L. nobilis on immunosuppression have been reported, the detailed underlying mechanism remains unclear. In this study, to elucidate the anti-inflammatory mechanism of L. nobilis, we examined the effect of L. nobilis leaf extract on inflammasome activation in mouse bone marrow-derived macrophages. L. nobilis leaf extract inhibited NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation, which was associated with caspase-1 activation, interleukin-1β secretion, and apoptosis-associated speck-like protein containing a CARD (ASC) pyroptosome complex formation. We also observed that 1,8-cineole, the major component of L. nobilis extract, consistently suppressed NLRP3 inflammasome activation. Furthermore, L. nobilis leaf extract attenuated the in vivo expression of proinflammatory cytokines in an acute lung injury mouse model. Our results provide the first evidence that L. nobilis leaf extract modulates inflammatory signaling by suppressing inflammasome activation.     

长江鲢、鳙个体发育过程中的表型变化

采用多元分析方法,对采自长江老江河国家级四大家鱼原种场255尾1—5龄鲢、鳙的30项形态度量数据进行了分析。聚类分析显示,鲢可明显地聚成欧氏距离相对较远的1龄组和2—5龄组,鳙也可聚成欧氏距离较远的1、2龄组与3—5龄组。判别分析显示,144尾鲢个体对所聚类的两个组别的判别准确率高达98.0%,111尾鳙个体对所聚类的两个组别的判别准确率也达90.7%。这表明,在幼体向成体的发育过程中,鲢和鳙在形态上均存在着两个具有显著差异阶段。单因素方差分析显示,鲢两个组别之间有18个参数差异极显著,4个差异显著,其中10个显著或极显著地变小,12个显著或极显著地变大。鳙两个组别间有极显著和显著差异的参数分别有14个和3个,其中极显著或显著差异变小和变大的分别有12个和5个。这表明在鲢、鳙个体发育过程中,分别有73.3%和56.7%的特征参数具有生长异速现象。因此,在根据形态鉴别物种、分析种群差异、确立种质标准和作生长退算时,均应考虑所选用特征的生长异速现象。     

Excising stem samples underwater at native tension does not induce xylem cavitation

Xylem resistance to water stress‐induced cavitation is an important trait that is associated with drought tolerance of plants. The level of xylem cavitation experienced by a plant is often assessed as the percentage loss in conductivity (PLC) at different water potentials. Such measurements are constructed with samples that are excised underwater at native tensions. However, a recent study concluded that cutting conduits under significant tension induced cavitation, even when samples were held underwater during cutting. This resulted in artificially increased PLC because of what we have termed a ‘tension‐cutting artefact’. We tested the hypothesized tension‐cutting artefact on five species by measuring PLC at native tension compared with after xylem tensions had been relaxed. Our results did not support the tension‐cutting artefact hypothesis, as no differences were observed between native and relaxed samples in four of five species. In a fifth species (Laurus nobilis), differences between native and relaxed samples appear to be due to vessel refilling rather than a tension‐cutting effect. We avoided the tension‐cutting artefact by cutting samples to slightly longer than their measurement length and subsequent trimming of at least 0.5 cm of sample ends prior to measurement.     

Temperature cues phenological synchrony in ant‐mediated seed dispersal

Species‐specific climate responses within ecological communities may disrupt the synchrony of co‐evolved mutualisms that are based on the shared timing of seasonal events, such as seed dispersal by ants (myrmecochory). The spring phenology of plants and ants coincides with marked changes in temperature, light and moisture. We investigate how these environmental drivers influence both seed release by early and late spring woodland herb species, and initiation of spring foraging by seed‐dispersing ants. We pair experimental herbaceous transplants with artificial ant bait stations across north‐ and south‐facing slopes at two contrasting geographic locations. This use of space enables robust identification of plant fruiting and ant foraging cues, and the use of transplants permits us to assess plasticity in plant phenology. We find that warming temperatures act as the primary phenological cue for plant fruiting and ant foraging. Moreover, the plasticity in plant response across locations, despite transplants being from the same source, suggests a high degree of portability in the seed‐dispersing mutualism. However, we also find evidence for potential climate‐driven facilitative failure that may lead to phenological asynchrony. Specifically, at the location where the early flowering species (Hepatica nobilis) is decreasing in abundance and distribution, we find far fewer seed‐dispersing ants foraging during its fruit set than during that of the later flowering Hexastylis arifolia. Notably, the key seed disperser, Aphaenogaster rudis, fails to emerge during early fruit set at this location. At the second location, A. picea forages equally during early and late seed release. These results indicate that climate‐driven changes might shift species‐specific interactions in a plant–ant mutualism resulting in winners and losers within the myrmecochorous plant guild.     

Phytochemical analysis and in vitro antiviral activities of the essential oils of seven Lebanon species

The chemical composition of the essential oils of Laurus nobilis, Juniperus oxycedrus ssp. oxycedrus, Thuja orientalis, Cupressus sempervirens ssp. pyramidalis, Pistacia palaestina, Salvia officinalis, and Satureja thymbra was determined by GC/MS analysis. Essential oils have been evaluated for their inhibitory activity against SARS-CoV and HSV-1 replication in vitro by visually scoring of the virus-induced cytopathogenic effect post-infection. L. nobilis oil exerted an interesting activity against SARS-CoV with an IC(50) value of 120 microg/ml and a selectivity index (SI) of 4.16. This oil was characterized by the presence of beta-ocimene, 1,8-cineole, alpha-pinene, and beta-pinene as the main constituents. J. oxycedrus ssp. oxycedrus oil, in which alpha-pinene and beta-myrcene were the major constituents, revealed antiviral activity against HSV-1 with an IC(50) value of 200 microg/ml and a SI of 5.     

New evidence for a role of vessel-associated cells and phloem in the rapid xylem refilling of cavitated stems of Laurus nobilis L.

Xylem recovery from embolism was studied in Laurus nobilis L. stems that were induced to cavitate by combining negative xylem pressure potentials (P_X = ?1.1 MPa) with positive air pressures (P_C) applied using a pressure collar. Xylem refilling was measured by recording the percentage loss of hydraulic conductance (PLC) with respect to the maximum 2 min, 20 min and 15 h after pressure release. Sodium orthovanadate (an inhibitor of many ATP‐ases) strongly inhibited xylem refilling while fusicoccin (a stimulator of the plasma membrane H⁺‐ATPase) promoted complete embolism reversal. So, the refilling process was interpreted to result from energy‐dependent mechanisms. Stem girdling induced progressively larger inhibition to refilling the nearer to the embolized stem segment phloem was removed. The starch content of wood parenchyma was estimated as percentages of ray and vasicentric cells with high starch content with respect to the total, before and after stem embolism was induced. A closely linear positive relationship was found to exist between recovery from PLC and starch hydrolysis. This, was especially evident in vasicentric cells. A mechanism for xylem refilling based upon starch to sugar conversion and transport into embolized conduits, assisted by phloem pressure‐driven radial mass flow is proposed.     

A second‐generation genetic linkage map for bighead carp (Aristichthys nobilis) based on microsatellite markers

Bighead carp (Aristichthys nobilis) is an important aquaculture fish worldwide. Genetic linkage maps for the species were previously reported, but map resolution remained to be improved. In this study, a second‐generation genetic linkage map was constructed for bighead carp through a pseudo‐testcross strategy using interspecific hybrids between bighead carp and silver carp. Of the 754 microsatellites genotyped in two interspecific mapping families (with 77 progenies for each family), 659 markers were assigned to 24 linkage groups, which were equal to the chromosome numbers of the haploid genome. The consensus map spanned 1917.3 cM covering 92.8% of the estimated bighead carp genome with an average marker interval of 2.9 cM. The length of linkage groups ranged from 52.2 to 133.5 cM with an average of 79.9 cM. The number of markers per linkage group varied from 11 to 55 with an average of 27.5 per linkage group. Normality tests on interval distances of the map showed a non‐normal marker distribution; however, significant correlation was found between the length of linkage group and the number of markers below the 0.01 significance level (two‐tailed). The length of the female map was 1.12 times that of the male map, and the average recombination ratio of female to male was 1.10:1. Visual inspection showed that distorted markers gathered in some linkage groups and in certain regions of the male and female maps. This well‐defined genetic linkage map will provide a basic framework for further genome mapping of quantitative traits, comparative mapping and marker‐assisted breeding in bighead carp.