Effects of cryopreservation techniques on the preservation of ear skin – An alternative approach to conservation of jaguar,Panthera onca (Linnaeus, 1758)

Currently, it has been observed that a considerable segment of the jaguar population is declining mainly because of hunting, and destruction and fragmentation of habitat. Given this scenario, efforts of the scientific community have been concentrated on the development of conservation strategies, such as the formation and use of somatic sample banks. We aimed to assess the effects of cryopreservation techniques of the ear skin of jaguar [slow freezing (SF) or direct vitrification in cryovials (DVC) or solid-surface vitrification (SSV)] on the morphological analysis and cell ability during the culture. All cryopreserved fragments regardless of the technique used, showed a reduction in the dermis and total thickness of the skin. Although a collagen matrix similar to the control group (fresh) has been observed only for the fragments from SF and SSV groups, all cryopreserved techniques were able to maintain normal patterns of the fibroblasts. Moreover, DVC and SSV methods maintained the proliferative activity of the tissues even after warming. After the culture, SF and SSV techniques were efficient for the recovery of the somatic cells according to most of the evaluated parameters, especially with regard to the duration of culture and cell metabolic activity. In conclusion, SSV was found to be a more efficient technique for cryopreserving jaguar skin when compared to DVC and SF. These results are relevant for the formation of somatic resource banks of this species, directed at cryopreserving adequate samplings of different individuals and generations for future applications in regenerative medicine, and assisted reproductive technologies.     

Scale-dependent interactions between intrinsic and extrinsic processes reduce variability in protist populations

Interactions between intrinsic processes and extrinsic fluctuations can positively impact population persistence in ways often not predicted by classic ecological models. These interactions only arise when the intrinsic and extrinsic processes operate on the proper relative scales in time or space. Both metapopulation theory and resonance/attenuation theory suggest that interactions which lower population variability will occur when the intrinsic and extrinsic process occur on similar time scales. I performed an aquatic protist microcosm experiment to investigate how the relative frequencies of extrinsic density perturbations and intrinsic resource pulses impacted population variability. Population variability was lowest in the treatments of intermediate frequency, in which the extrinsic fluctuations and intrinsic processes were on the same time scale. This result is consistent with general theoretical predictions, and empirically documents the importance of considering scale in interactions between intrinsic and extrinsic processes that positively impact population persistence.     

Diet overlap among three sympatric African annual killifish species Nothobranchius spp. from Mozambique

The diet patterns of three Nothobranchius species (N. furzeri, N. orthonotus and N. rachovii), small, short‐lived annual killifish from temporary pools in African savannah were investigated. Four sites with contrasting fish density and water surface area were sampled in 2008 and 2009 in southern Mozambique. Stomach content analysis showed that all the species examined were generalists, with diets largely based on aquatic invertebrates. The same invertebrate prey categories were consumed by all three species, but their relative proportions varied across species. The largest species, N. orthonotus, showed the most distinct diet and consumed vertebrates (juvenile lungfish Protopterus annectens and larval Amphibia) and a relatively high proportion of Odonata, Coleoptera and Ephemeroptera larvae. The diet of the other two species (N. furzeri and N. rachovii) showed a stronger overlap, did not include vertebrates, but was rich in small crustaceans (Cladocera, Copepoda, Ostracoda and Conchostraca). Mosquito (Diptera) larvae formed only a negligible part of the diet of all the three species.     

Effects of elevated ozone on chlorophyll <Emphasis Type="Italic">a</Emphasis> fluorescence in symptomatic and asymptomatic leaves of two tomato genotypes

Two different genotypes of Lycopersicon esculentum Mill. (cv. Cuor di Bue, O₃-sensitive and line 93.1033/1, O₃-resistant) were treated with a single dose of ozone (150 mm³ m⁻³ for 3 h). The PS 2 activity was examined by measurements of chlorophyll a fluorescence on symptomatic and asymptomatic leaves. Symptoms were evident on the 4^th leaves from the bottom, in both genotypes, while the 2^nd leaves of the line 93.1033/1 were asymptomatic. In these leaves, the net photosynthetic rate (P_N) did not change even if the F_v/F_m ratio significantly decreased. A strong reduction in P_N, mostly due to the stomatal closure, was observed in Cuor di Bue. The non photochemical quenching coefficient (q_NP) and the degree of PS 2 reaction centres closure (1-q_P) were higher, while the quantum efficiency of PS 2 photochemistry (Φ_PS2) and quantum efficiency of excitation energy capture (Φ_exc.) were lower in O₃ treated leaves of both genotypes. The limitation of photosynthesis was shown also by a decrease in the parameter %P, which diminished compared to controls in both genotypes. The response of the two genotypes for the energy fraction dissipated as thermal energy in the PS 2 antennae (%D) was similar. The fraction of %P remained lower during the recovery in symptomatic leaves of the resistant line as compared to the controls, whereas %X, which represents the amount of light energy that is not utilized in photochemistry or dissipated in the PS 2 antennae, significantly rose in the asymptomatic leaves of this line and in both the leaves of Cuor di Bue. From data obtained we concluded that ozone affected the plants independently on the appearance of visible symptoms of injury because the leaves without visible symptoms of both the genotypes were negatively influenced.     

Habitat-associated morphological divergence in two Neotropical fish species

We examined intraspecific morphological diversification between river channel and lagoon habitats for two Neotropical fish ( Bryconops caudomaculatus , Characidae; Biotodoma wavrini , Cichlidae). We hypothesized that differences between habitats (e.g. flow regime, foraging opportunities) might create selective pressures resulting in morphological divergence between conspecific populations. We collected fish from four channel-lagoon habitat pairs in the Río Cinaruco, Venezuela, and compared body morphology using geometric morphometrics. There were two aspects of divergence in both species: (1) placement of maximum body depth and (2) orientation of the mouth. For both species, maximum body depth was positioned more anteriorly (i.e. fusiform) in the river channel than in lagoons. Both species exhibited a relatively terminal mouth in lagoons compared to the channel. The mouth of B. caudomaculatus was relatively upturned, whereas the mouth of B. wavrini was relatively subterminal, in channel habitats. Observed morphological patterns are consistent with functional morphological principles suggesting adaptive divergence. We also show that spatial distance between habitats, presumably reflecting rates of population mixing, appears to have constrained diversification. For both species, morphological divergence increased with distance between habitats. Thus morphological divergence between channel and lagoon habitats apparently reflects a balance between diversification driven by natural selection, and homogenization driven by population mixing.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 689–698.     

白腐真菌血红密孔菌漆酶复合酶预处理烟梗丝的响应面法优化

烟梗是烟草工业的重要副产物,也是宝贵的自然资源。本研究首先利用白腐菌漆酶对烟梗丝进行预处理,提升了添加烟梗丝的卷烟品质;然后分别以木质素、纤维素、半纤维素和果胶的降解率为响应值,采用Box-Behnken设计建立方程模型,对漆酶、纤维素酶、半纤维素酶和果胶酶组成的复合酶预处理烟梗丝条件进行了优化。结果表明：每100g烟梗丝加入30U漆酶,在料液比为35%、温度为30℃、酶解pH为5处理48h的条件下预处理的烟梗丝对提升卷烟品吸效果最佳,烟梗丝中木质素、纤维素、半纤维素和果胶的降解率分别为20.16%、15.10%、7.20%和12.40%;为获得与之相同的各组分降解率,响应面法优化漆酶复合酶最佳处理条件为：每100g烟梗丝加入漆酶14.72U、纤维素酶1.00U、半纤维素酶1.00U、果胶酶8.45U。验证发现烟梗丝各组分降解率实测值与理论值无显著性差异,且显微结构观察显示复合酶处理后的烟梗丝表面致密结构被破坏,孔洞数量明显增加。本研究获得的白腐菌漆酶预处理后的烟梗丝在卷烟中的添加能有效改善卷烟品质,且漆酶复合酶的使用大幅减少了漆酶的用量,降低了漆酶预处理烟梗丝的成本,为废弃烟梗生物质的资源化利用提供了重要依据。     

安徽白术资源调查

目的：了解安徽省内白术资源情况。方法：实地调查。结果：安徽省内有野生白术品种“舒州术”、“歙州术”和“祁术”,但都濒临灭绝;皖南山区和亳州地区有栽培白术并作为药材商品供应市场。结论：野生白术资源濒危,殛待保护;皖南栽培白术产量少,分散;亳州栽培白术面积大,产量高。发展白术栽培,有利于地方经济的发展。     

Resource Ratios and Phytoplankton Species Composition in a Strongly Stratified Lake

The epilimnetic phytoplankton and its relations to nutrient content in Lake Verevi through the whole vegetation period in 2000 were studied. Lake Verevi (surface 12.6 ha, mean depth 3.6 m, maximum depth 11 m) is a hypertrophic hard-water lake, where the so-called spring meromixis occurs due to an extremely warm spring. Most dissolved nutrients in the epilimnion were low already in spring, and their concentrations were quite stable during the study period. The concentration of total silicon was very low in spring but increased rapidly in summer. Total phosphorus followed the pattern for stratified eutrophic lakes, and total nitrogen was quite high. The stoichiometric N:P ratio fluctuated between 25 and 81. The dynamics of phytoplankton biomass with a spring peak from April to May and a late summer peak from July to August is typical of Estonian eutrophic lakes. Green algae and chrysophytes occurred in the phytoplankton throughout the vegetation period. The spring peak was dominated by diatoms (Synedra ulna and Synedra acus var. angustissima) and the summer peak was caused by Aphanizomenon klebahnii and Ceratium hirundinella. The study showed that in physically stratified systems, the total concentration of limiting resources and plain physical factors (light and temperature) may be more important in the determination of phytoplankton dominants than different resource ratios. A combination of light and temperature optimum, along with nutrient utilization and transport capacity, effectively segregates phytoplankton species and can be used for the explanation of seasonal succession pattern.     

Leaf Photosynthesis in Eight Almond Tree Cultivars

Response of gas exchange traits to irradiance were studied in eight almond tree (Prunus amygdalus) cultivars: Desmayo Largueta, Falsa Barese, Garrigues, Lauranne, Marcona, Masbovera, Nonpareil and Ramillete, grafted on a hybrid rootstock almond × peach GF-677. From these responses cultivars can be classified from the best to the worst photosynthetic performance as follows: Falsa Barese, Masbovera, Marcona, Nonpareil, Ramillete, Desmayo Largueta, Lauranne and Garrigues. The highest net photosynthetic rate was 20.3 μmol m⁻² s⁻¹ in Falsa Barese. In the absence of water stress, photosynthetic rate was not limited by stomatal conductance. Consequently, non-stomatal limitations prevailed under such conditions. This revised version was published online in July 2006 with corrections to the Cover Date.