猪白细胞抗原复合体Ⅰ类和Ⅱ类研究进展

猪主要组织相容性复合体又称猪白细胞抗原复合体（SLA）,是猪基因组中基因密度最高的区域之一,也是多态性最高的区域。许多研究表明SLA在抗原提呈及免疫调节等方面起着重要的作用,其基因及基因组学研究在以猪为替代模型的人-猪器官移植、癌症、变态反应、猪的生产数量性状及对感染性疾病的应答、疫苗研制等方面都是热点。我们就目前Ⅰ类和Ⅱ类SLA分子功能基因多态性及与机体免疫水平、抗病育种和生产性状的相关性作一综述。     

Evolutionary transitions among dioecy,androdioecy and hermaphroditism in limnadiid clam shrimp (Branchiopoda: Spinicaudata)

Examinations of breeding system transitions have primarily concentrated on the transition from hermaphroditism to dioecy, likely because of the preponderance of this transition within flowering plants. Fewer studies have considered the reverse transition: dioecy to hermaphroditism. A fruitful approach to studying this latter transition can be sought by studying clades in which transitions between dioecy and hermaphroditism have occurred multiple times. Freshwater crustaceans in the family Limnadiidae comprise dioecious, hermaphroditic and androdioecious (males + hermaphrodites) species, and thus this family represents an excellent model system for the assessment of the evolutionary transitions between these related breeding systems. Herein we report a phylogenetic assessment of breeding system transitions within the family using a total evidence comparative approach. We find that dioecy is the ancestral breeding system for the Limnadiidae and that a minimum of two independent transitions from dioecy to hermaphroditism occurred within this family, leading to (1) a Holarctic, all‐hermaphrodite species, Limnadia lenticularis and (2) mixtures of hermaphrodites and males in the genus Eulimnadia. Both hermaphroditic derivatives are essentially females with only a small amount of energy allocated to male function. Within Eulimnadia, we find several all‐hermaphrodite populations/species that have been independently derived at least twice from androdioecious progenitors within this genus. We discuss two adaptive (based on the notion of ‘reproductive assurance’) and one nonadaptive explanations for the derivation of all‐hermaphroditism from androdioecy. We propose that L. lenticularis likely represents an all‐hermaphrodite species that was derived from an androdioecious ancestor, much like the all‐hermaphrodite populations derived from androdioecy currently observed within the Eulimnadia. Finally, we note that the proposed hypotheses for the dioecy to hermaphroditism transition are unable to explain the derivation of a fully functional, outcrossing hermaphroditic species from a dioecious progenitor.     

Re-establishing a saltmarsh vegetation structure in a changing climate

Summary A major management decision in an ecological restoration or rehabilitation project is whether supplementary planting or natural vegetation regeneration is the better alternative or if a combination can be applied. Management decisions are further complicated when the project involves saltmarsh as tidal cycles, the effects of salinity and sea level rise add to the complexity of decisions. The ecological values of the saltmarsh community in Australia were only recognized relatively recently but the endangered ecological community listing in 1994 (under the New South Wales Threatened Species Conservation Act 1995) highlighted the need to protect, rehabilitate and restore saltmarsh. This project measured vegetation change after soil profile reconstruction in saltmarsh surrounding Sponsors Lagoon, Fingal Peninsula in north coastal New South Wales, Australia. Restored sites (planted and non‐planted) were compared with nearby disturbed (control) and reference sites. The dominant species in the community to be restored were Saltwater Couch (Sporobolus virginicus), Suaeda (Suaeda australis), Sarcocornia (Sarcocornia quinqueflora ssp. quinqueflora and Sea Rush (Juncus kraussii ssp. australiensis). Changes in percentage cover of the species in the first three years after soil reconstruction work showed that the dominant Saltwater Couch established only from vegetative growth arising from remnant vegetation but there was strong seedling regeneration of several other species. It was concluded that planting is important for species that are less vagile, in larger, denuded parts of this site where their resilience is lower and natural regeneration potential is limited. An understanding of the biology of the individual species is therefore likely to be essential in saltmarsh restoration projects. A combination of techniques, incorporating planting of slower establishing species and encouragement of seed‐germinated colonizers is useful for initial site stabilization and progressive ecological recovery at this site. The inclusion of migration zones in the planning phase will allow for the long‐term viability of this restoration project.     

Design of multispecific protein sequences using probabilistic graphical modeling

In nature, proteins partake in numerous protein– protein interactions that mediate their functions. Moreover, proteins have been shown to be physically stable in multiple structures, induced by cellular conditions, small ligands, or covalent modifications. Understanding how protein sequences achieve this structural promiscuity at the atomic level is a fundamental step in the drug design pipeline and a critical question in protein physics. One way to investigate this subject is to computationally predict protein sequences that are compatible with multiple states, i.e., multiple target structures or binding to distinct partners. The goal of engineering such proteins has been termed multispecific protein design. We develop a novel computational framework to efficiently and accurately perform multispecific protein design. This framework utilizes recent advances in probabilistic graphical modeling to predict sequences with low energies in multiple target states. Furthermore, it is also geared to specifically yield positional amino acid probability profiles compatible with these target states. Such profiles can be used as input to randomly bias high‐throughput experimental sequence screening techniques, such as phage display, thus providing an alternative avenue for elucidating the multispecificity of natural proteins and the synthesis of novel proteins with specific functionalities. We prove the utility of such multispecific design techniques in better recovering amino acid sequence diversities similar to those resulting from millions of years of evolution. We then compare the approaches of prediction of low energy ensembles and of amino acid profiles and demonstrate their complementarity in providing more robust predictions for protein design. Proteins 2010. © 2009 Wiley‐Liss, Inc.     

Leaf epidermal characteristics of Asiatic Buddleja L. under scanning electron microscope: Insights into chromosomal and taxonomic significance

The leaf epidermis of all 23 species from Asian Buddleja was investigated with scanning electron microscopy (SEM). Characteristics of trichome type, stomatal shape, cuticular membrane on adaxial and abaxial epidermis, inner margin of outer stomatal ledge and ornamentation of outer stomatal ledge are presented in this study. Among the Buddleja species, some distinct epidermal patterns were observed. These can be used to characterize and identify different sections among the Asian Buddleja species, viz. Alternifoliae, Curviflorae and Rectiflorae. In general, stomatal length of Buddleja increases with ploidy level. This character can be used to distinguish diploids from polyploids without preparation of caryograms. Based on this correlation Buddleja microstachya, B. subcapitata and B. bhutanica are characterized to be diploids, as concluded from their stomatal dimensions. Leaf epidermis characters can also be used to differentiate species pairs that are easily confused with each other, viz., B. asiatica and B. bhutanica, B. albiflora and B. nivea, B. candida and B. fallowiana, B. delavayi and B. forrestii, B. japonica and B. lindleyana, B. officinalis and B. paniculata.     

CO_2倍增和转Bt水稻对二化螟幼虫的生理影响

通过开顶式气室研究了CO2浓度倍增(750vs.375μL/L)对取食转Bt水稻及其对照亲本秀水11的二化螟Chilo suppressalis(Walker)幼虫体内代谢酶乙酰胆碱酯酶(AChE)和保护酶(超氧化物歧化酶SOD、过氧化物酶POD和过氧化氢酶CAT)活力的影响,以期明确该类害虫对大气CO2浓度升高及转Bt水稻的生理响应。研究结果表明:(1)AChE受CO2浓度水平影响显著,与对照CO2处理相比,高CO2条件下该酶活力显著降低;(2)高CO2水平及水稻中Bt毒素蛋白的存在均会导致二化螟幼虫体内POD活力显著降低,SOD初期活力显著升高,但不能维持较长时间,CAT活力表现为先升后降的特点;(3)当受到水稻品种、CO2浓度水平和取食时间的综合影响时,以上代谢酶和保护酶活力会发生显著变化。短时间内二化螟幼虫可通过体内以上生理代谢调节减缓受CO2浓度升高和水稻中Bt毒素蛋白的不利影响,但长时间环境胁迫下这种应对不利环境的响应机制将会失去作用,最终导致种群适合度的降低。     

Quantitative evaluation of marine protein contribution in ancient diets based on nitrogen isotope ratios of individual amino acids in bone collagen: An investigation at the Kitakogane Jomon site

Nitrogen stable isotopes analysis of individual bone collagen amino acids was applied to archeological samples as a new tool for assessing the composition of ancient human diets and calibrating radiocarbon dates. We used this technique to investigate human and faunal samples from the Kitakogane shell midden in Hokkaido, Japan (5,300–6,000 cal BP). Using compound‐specific nitrogen isotope analysis of individual amino acids, we aimed to estimate i) the quantitative contribution of marine and terrestrial protein to the human diet, and ii) the mean trophic level (TL) from which dietary protein was derived from marine ecosystems. Data were interpreted with reference to the amino acid trophic level (TL_AA) model, which uses empirical amino acid δ¹⁵N from modern marine fauna to construct mathematical equations that predict the trophic position of organisms. The TL_AA model produced realistic TL estimates for the Kitakogane marine animals. However, this model was not appropriate for the interpretation of human amino acid δ¹⁵N, as dietary protein is derived from both marine and terrestrial environments. Hence, we developed a series of relevant equations that considered the consumption of dietary resources from both ecosystems. Using these equations, the mean percentage of marine protein in the Kitakogane human diet was estimated to be 74%. Although this study is one of the first systematic investigations of amino acid δ¹⁵N in archeological bone collagen, we believe that this technique is extremely useful for TL reconstruction, palaeodietary interpretation, and the correction of marine reservoir effects for radiocarbon dating. Am J Phys Anthropol 143:31–40, 2010. © 2010 Wiley‐Liss, Inc.     

A calorimetric and spectroscopic comparison of the effects of ergosterol and cholesterol on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes

We performed comparative DSC and FTIR spectroscopic measurements of the effects of cholesterol (Chol) and ergosterol (Erg) on the thermotropic phase behavior and organization of DPPC bilayers. Ergosterol is the major sterol in the biological membranes of yeasts, fungi and many protozoa. It differs from Chol in having two additional double bonds, one in the steroid nucleus at C7-8 and another in the alkyl chain at C22-23. Erg also has an additional methyl group in the alkyl chain at C24. Our DSC studies indicate that the incorporation of Erg is more effective than Chol is in reducing the enthalpy of the pretransition. At lower concentrations Erg is also more effective than Chol in reducing the enthalpies of both the sharp and broad components of main phase transition. However, at sterol concentrations from 30 to 50 mol%, Erg is generally less effective at reducing the enthalpy of the broad components and does not completely abolish the cooperative hydrocarbon chain-melting phase transition at 50 mol%, as does Chol. Nevertheless, in this higher ergosterol concentration range, there is no evidence of the formation of ergosterol crystallites. Our FTIR spectroscopic studies demonstrate that Erg incorporation produces a similar ordering of liquid-crystalline DPPC bilayers as does Chol, but an increased degree of hydrogen bonding of the fatty acyl carbonyl groups in the glycerol backbone region of the DPPC bilayer. These and other results indicate that Erg is less miscible in DPPC bilayers at higher concentrations than is Chol. Finally, we provide a tentative molecular explanation for the comparative experimental and computation results obtained for Erg and Chol in phospholipid bilayers, emphasizing the dynamic conformational differences between these two sterols.