Reproductive costs of sons and daughters in Rocky Mountain bighorn sheep

Differential maternal investment theory predicts that in sexuallydimorphic and polygynous species mothers should invest morein sons than in daughters. We tested the hypothesis that bighornewes that raise sons incur greater reproductive costs than ewesthat raise daughters. Although ewe mass gain during lactationand subsequent winter body mass loss were independent of lambsex, lambs born the year following the weaning of a son hadlower survival than lambs born after a daughter. The effectsof lamb sex on subsequent reproductive success of ewes becamemore evident at high population density. Lamb sex did not affectmaternal survival. Population density, weather, and ewe agedid not alter the relationship between lamb sex and subsequentreproductive success of the ewe. The year after weaning a son,ewes were more likely to have a daughter than a son, while ewesthat had previously weaned a daughter had similar numbers ofsons and daughters. Our results show that for bighorn sheepewes, sons have a greater life-history cost than daughters,suggesting a differential maternal investment in the sexes.     

Whole-genome analysis of the ammonia-oxidizing bacterium, Nitrosomonas eutropha C91: implications for niche adaptation

Analysis of the structure and inventory of the genome of Nitrosomonas eutropha C91 revealed distinctive features that may explain the adaptation of N. eutropha-like bacteria to N-saturated ecosystems. Multiple gene-shuffling events are apparent, including mobilized and replicated transposition, as well as plasmid or phage integration events into the 2.66 Mbp chromosome and two plasmids (65 and 56 kbp) of N. eutropha C91. A 117 kbp genomic island encodes multiple genes for heavy metal resistance, including clusters for copper and mercury transport, which are absent from the genomes of other ammonia-oxidizing bacteria (AOB). Whereas the sequences of the two ammonia monooxygenase and three hydroxylamine oxidoreductase gene clusters in N. eutropha C91 are highly similar to those of Nitrosomonas europaea ATCC 19718, a break of synteny in the regions flanking these clusters in each genome is evident. Nitrosomonas eutropha C91 encodes four gene clusters for distinct classes of haem-copper oxidases, two of which are not found in other aerobic AOB. This diversity of terminal oxidases may explain the adaptation of N. eutropha to environments with variable O(2) concentrations and/or high concentrations of nitrogen oxides. As with N. europaea, the N. eutropha genome lacks genes for urease metabolism, likely disadvantaging nitrosomonads in low-nitrogen or acidic ecosystems. Taken together, this analysis revealed significant genomic variation between N. eutropha C91 and other AOB, even the closely related N. europaea, and several distinctive properties of the N. eutropha genome that are supportive of niche specialization.     

5'-Triphosphate-Short Interfering RNA: Potent Inhibition of Influenza A Virus Infection by Gene Silencing and RIG-I Activation

Limited protection of current vaccines and antiviral drugs against influenza A virus infection underscores the urgent need for development of novel anti-influenza virus interventions. While short interfering RNA (siRNA) has been shown to be able to inhibit influenza virus infection in a gene-specific manner, activation of the retinoic acid-inducible gene I protein (RIG-I) pathway has an antiviral effect in a non-gene-specific mode. In this study, we designed and tested the anti-influenza virus effect of a short double-stranded RNA, designated 3p-mNP1496-siRNA, that possesses dual functions: an siRNA-targeting influenza NP gene and an agonist for RIG-I activation. This double-stranded siRNA possesses a triphosphate group at the 5' end of the sense strand and is blunt ended. Our study showed that 3p-mNP1496-siRNA could potently inhibit influenza A virus infection both in cell culture and in mice. The strong inhibition effect was attributed to its siRNA function as well as its ability to activate the RIG-I pathway. To the best of our knowledge, this is the first report that the combination of siRNA and RIG-I pathway activation can synergistically inhibit influenza A virus infection. The development of such dual functional RNA molecules will greatly contribute to the arsenal of tools to combat not only influenza viruses but also other important viral pathogens.     

YopR impacts type III needle polymerization in Yersinia species

A hallmark of Yersinia type III machines is the presence of needles extending from the bacterial surface. Needles perform two functions, serving as the conduits for the transport of effectors into immune cells but also acting as a sensor. The polymerized needle protein, YscF, is thought to perceive threshold levels of environmental calcium ions to trigger secretion. yopR ( yscH ) is a gene downstream of yscEFG , encoding the chaperones and principal building blocks of the needle. Here we investigated the contribution of YopR towards type III secretion and pathogenesis. Yersinia pestis KIM D27 mutants lacking yopR were defective for virulence in a mouse model of septicemic plague. yopR variants of Yersinia enterocolitica W22703 displayed a reduced ability to inject effectors into macrophages and required lower calcium concentrations to activate type III secretion than wild-type yersiniae. Furthermore, yopR mutants failed to assemble YscF into needle complexes and instead secreted YscF into the medium. These results imply that YopR may be involved in controlling the secretion of YscF, thereby impacting the assembly of type III machines. An alternative possibility, which YopR participates directly in the polymerization of YscF, seems less likely as YopR is not associated with purified needles.     

The Gallocyanin-Chrome Alum Stain; Influence of Methods of Preparation on Its Activity and Separation of Active Staining Compound

A dye, which is probably a cationic chelate, has been separated from a gallocyanin-chrome alum staining solution and prepared in the dry form. This dye is apparently the major staining compound. To prepare the chelate or dye, dissolve 150 mg of gallocyanin and 15 gm of chrome alum in 100 ml of distilled water and boil for 10-20 min, cool, filter, wash the precipitate with sufficient distilled water to restore the volume of the filtrate to 100 ml, then add concentrated NH₄OH until the pH is raised to 8-8.5. Filter, with suction, through a medium porosity fritted glass funnel. Wash with 100-200 ml of anhydrous ethyl ether and air dry the precipitate. This ratio of chrome alum to gallocyanin and the 10-20 min boiling time are optimal for preparation of the staining solution, which may be used either for staining or for separation of the chelate in its dry form. From the dried chelate, the staining solution is prepared as a 3% solution in1 N H₂SO₄ and a staining time of 16-24 hr is required. No differentiation is needed; the stain is self-limiting.     

A Self-Limiting, Highly Selective Chromium-Hematoxylin Stain

A compound, which is probably a cationic chelate, can be isolated as a dry powder from a hematoxylin-chrome alum lake. In aqueous acid solution this compound is an excellent nuclear stain which is extremely selective, very resistant to acids and alcohols, and self-limiting. Staining time may vary from 20 min to 16 hr without causing significant differences in staining intensity. To prepare the dry stain, dissolve 10 gm of hematoxylin, 10 gm of NaOH and 70 gm of chrome alum in 600 ml of distilled water, boil 20 min, cool and filter, allowing the filtrate to drop into 3.5 liters of absolute alcohol. Filter off the precipitate formed in the alcohol, and air dry it at room temperature. The staining solution is prepared by dissolving 3 gm of the dried precipitate in 100 ml of 3% HCl.     

Iron Hematoxylin Chelates. I. The Weil Staining Bath

The procedure for the preparation of the staining solution for the Weil myelin sheath stain was systematically varied in respect to pH, concentration, time, temperature and relative proportions of the ingredients. The results were explainable on the basis of the presence of a number of iron hematoxylin chelates in the staining bath. Compounds of the form of [Fe_nHem]^m+ are nuclear stains, those of the form of [FeHem_n]^m± are myelin sheath stains while the precipitate is probably [Fe_nHem_y]_x^m±. The following procedure for the stain is recommended. Mix equal portions of a 0.25% solution of ripened hematoxylin prepared from a 10% alcoholic solution and 1% ferric ammonium sulphate and use immediately. Preferably, the solutions should be at a temperature of about 5 C and the staining done in the refrigerator, but room temperature may be used. Higher temperatures are contraindicated. Hematein should not be substituted for ripened hematoxylin; the resulting stains are too weak to be usable. The absorbance of hematein is no measure of the concentration of the component that stains myelin sheaths. Hematein apparently consists largely of a sparingly soluble highly colored inactive compound.