抗黄体酮联合Aromatase抑制剂或iNOS终止恒河猴妊娠

[目的]评价抗黄体酮(mifepristone)联合Aromatase抑制剂(letrozole或aminoglutethimide)或iNOS抑制剂(aminoguandine)是否能有效终止恒河猴早期妊娠。[方法]将30只猴子随机分为5组(治疗组每组6只,对照组6只),并在妊娠30,31和32天进行如下处理:对照组,每只动物1ml安慰剂;A组,Mifepristone(1mg/kg,sc.);B组,Mifepristone(sc.)+Letrozole(2.5mg/只sc.);C组,Mifepristone(1mg/kg,sc.)+aminoglute-chimide(50mg/kgsc.,bid);D组,Mifepristone(1mg/kg,sc.)+aminoguanidine(150mg/kg,sc.,bid)。所有妊娠猴在妊娠29天通过超声波确认。[结果]在B、C、D组,所有的动物的妊娠都在妊娠早期被终止(6/6)。A组和对照组的妊娠终止率分别为3/6和2/6。同时,联合用药能够有效排空子宫腔和减少出血。[结论]该处理能有效地终止恒河猴早期妊娠。联合用药比用于女人的妊娠治疗更有效,并减少了流血时间,或许可以代替目前的终止妊娠的医疗方法。     

Biochemical characterization of developmental stages of cycad somatic embryos

The effect of two light intensities (25 μmol m⁻²s⁻¹ and 50 μmol m⁻²s⁻¹) on four developmental stages ofCeratozamia mexicana somatic embryos growing on semisolid plant growth medium at 25°C was measured. Growth parameters included fresh weight, morphology, and invertase and peroxidase activity. Under low light conditions, fresh weight was greater in stages 1 and 2 than in stages 3 and 4. In addition, there was a high frequency of hyperhydricity and polyembryogenesis in stages 1 and 2, whereas stages 3 and 4 were nonhyperhydric and unbranched. Stages 2–4 were green. Under high light conditions, embryos had lower fresh weights and less hyperhydricity, and stages 2–4 were green. Under low light conditions, peroxidase activity was less, although stage 1 embryos under both light conditions showed the highest activity. Stage 1 embryos required three to four months to develop to stage 2 under high light conditions and two to three months under low light conditions. Invertase activity under low light conditions was minimal in stage 2. All embryos had low invertase activity under high light intensity, and stages 2–4 had high levels of glucose. Embryo development from stage 2 to the next and for each subsequent stage under high light conditions required three to four months, and under low light conditions required four to five months. Higher light intensity therefore promotes the speedy recovery of plants.

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Resumen  El efecto de dos intensidades de luz (25 μmol m⁻²s⁻¹ y 50 μmol m⁻²s⁻¹) fue registrado en cuatro estados de desarrollo de embriones somáticos deCeratozamia mexicana cultivados en medio semisólido, 25°C. Los parámétras de crecimiento incluyeron peso fresco, peso seco, morfología, y actividad peroxidasa e invertasa. Bajo condiciones de baja iluminación, el peso fresco de los estados 1 y 2 fue mayor que en los estados 3 y 4. Además, hubo una alta frecuencia de hiperhidratación y poliembriogénesis en estados 1 y 2, mientras que los estados 3 y 4 no resultaron hiperhidratados ni ramificados. Los estados 2–4 fueron verdes. Bajo alta iluminación, los embriones tuvieron un menor peso fresco y menos hiperhidratación. En baja iluminación la actividad peroxidasa fue menor, aunque en los embriones en estado 1 en ambas condiciones de iluminación mostraron la más alta actividad. Los embriones en estado 1 requirieron tres o cuatro meses para desarrollarse hasta el estado 2 bajo condiciones de alta iluminación; y dos o tres meses en baja iluminación. La actividad invertasa en condiciones de baja iluminación fue minima en el estado 2. Todos los embriones tuvieron altos nivelés de glucosa. El desarrollo de los embriones de estado 2 al siguiente y a los subsecuentes, bajo alta iluminación, requirió tres o cuatro meses, y bajo condiciones de baja iluminación requirió cuatro o cinco meses. Una alta intensidad luminosa parece promover la velocidad de recuperación de plantas.

     

Sequence and functional analyses of Haemophilus spp. genomic islands

Background

A major part of horizontal gene transfer that contributes to the diversification and adaptation of bacteria is facilitated by genomic islands. The evolution of these islands is poorly understood. Some progress was made with the identification of a set of phylogenetically related genomic islands among the Proteobacteria, recognized from the investigation of the evolutionary origins of a Haemophilus influenzae antibiotic resistance island, namely ICEHin1056. More clarity comes from this comparative analysis of seven complete sequences of the ICEHin1056 genomic island subfamily.

Results

These genomic islands have core and accessory genes in approximately equal proportion, with none demonstrating recent acquisition from other islands. The number of variable sites within core genes is similar to that found in the host bacteria. Furthermore, the GC content of the core genes is similar to that of the host bacteria (38% to 40%). Most of the core gene content is formed by the syntenic type IV secretion system dependent conjugative module and replicative module. GC content and lack of variable sites indicate that the antibiotic resistance genes were acquired relatively recently. An analysis of conjugation efficiency and antibiotic susceptibility demonstrates that phenotypic expression of genomic island-borne genes differs between different hosts.

Conclusion

Genomic islands of the ICEHin1056 subfamily have a longstanding relationship with H. influenzae and H. parainfluenzae and are co-evolving as semi-autonomous genomes within the 'supragenomes' of their host species. They have promoted bacterial diversity and adaptation through becoming efficient vectors of antibiotic resistance by the recent acquisition of antibiotic resistance transposons.     

Selective compounds define Hsp90 as a major inhibitor of apoptosis in small-cell lung cancer

The heat shock protein 90 (Hsp90) has a critical role in malignant transformation. Whereas its ability to maintain the functional conformations of mutant and aberrant oncoproteins is established, a transformation-specific regulation of the antiapoptotic phenotype by Hsp90 is poorly understood. By using selective compounds, we have discovered that small-cell lung carcinoma is a distinctive cellular system in which apoptosis is mainly regulated by Hsp90. Unlike the well-characterized antiapoptotic chaperone Hsp70, Hsp90 is not a general inhibitor of apoptosis, but it assumes this role in systems such as small-cell lung carcinoma, in which apoptosis is uniquely dependent on and effected through the intrinsic pathway, without involvement of caspase elements upstream of mitochondria or alternate pathways that are not apoptosome-channeled. These results provide important evidence for a transformation-specific interplay between chaperones in regulating apoptosis in malignant cells.     

Diet‐dependent female evolution influences male lifespan in a nuptial feeding insect

Theory predicts that lifespan will depend on the dietary intake of an individual, the allocation of resources towards reproduction and the costs imposed by the opposite sex. Although females typically bear the majority of the cost of offspring production, nuptial feeding invertebrates provide an ideal opportunity to examine the extent to which reproductive interactions through gift provisioning impose a cost on males. Here we use experimental evolution in an Australian ground cricket to assess how diet influences male lifespan and how the costs of mating evolve for males. Our findings show that males had significantly shorter lifespans in populations that adapted to a low‐quality diet and that this divergence is driven by evolutionary change in how females interact with males over reproduction. This suggests that the extent of sexual conflict over nuptial feeding may be under‐realized by focusing solely on the consequences of reproductive interactions from the female’s perspective.     

Genetic transformation of perennial tropical fruits

Summary Genetic transformation provides the means for modifying single horticultural traits in perennial plant cultivars without altering their phenotype. This capability is particularly valuable for perennial plants and tree species in which development of new cultivars is often hampered by their long generation time, high levels of heterozygosity, nucellar embryony, etc. Most of these conditions apply to many tropical and subtropical fruit crops. Targeting specific gene traits is predicated upon the ability to regenerate elite selections of what are generally trees from cell and tissue cultures. The integrity of the clone would thereby remain unchanged except for the altered trait. This review provides an overview of the genetic transformation of perennial tropical and subtropical fruit crops, i.e., citrus (Citrus spp.), banana and plantain (Musa groups AAA, AAB, ABB, etc.), mango (Mangifera indica L.), pineapple (Ananas comosus L.), avocado (Persea americana Mill.), passion fruit (Passiflora edulis L.), longan (Dimocarpus longan Lour.), and litchi (Litchi chinensis Sonn.).     

THE EFFECT OF ADDED NITROGEN ON THE RATE OF DECOMPOSITION OF ORGANIC MATTER

(1) N added to decomposing organic matter often has no effect or a negative effect on microbial activity, at least in the long term. More than 60 papers are cited in support of this statement.
(2) The negative effect of N is mainly found with recalcitrant organic matter with a high C/N ratio (straw, wood, etc.), whereas a positive effect of N is common for easily degradable organic material with low C/N ratio.
(3) The negative effect of N could be explained by: (i) N disturbs the outcome of competition between potent and less potent decomposers; (ii) through 'ammonia metabolite repression', N blocks production of certain enzymes, at least in basidiomycetes, and enhances breakdown of the most available cellulose, whereby recalcitrant lignocellulose accumulates; (iii) amino compounds condense with polyphenols and other decomposition products, forming 'browning precursors' which are toxic or inhibitory.
(4) The effect of adding N may depend on the microflora present.
(5) There are indications that some microorganisms have a 'luxury uptake' of N when it is present in sufficient amounts, thereby delaying N mineralization.
(6) The addition of N seems to increase the formation of water-soluble , brown, recalcitrant compounds, but to decrease the amount of humus formed.