Evaluation of frost resistant tuber-bearing solanum hybrids

Frost resistance of interspecific and varietal potato crosses was evaluated at Bogotá, Colombia using intact plants in a programmed low temperature growth cabinet. Plants were exposed to a 2 hour frost during the dark period and the minimum test temperature was successively lowered 1 C on subsequent nights. The foliage was visually scored for damage 10–12 hours after each frost. While most commercial varieties were killed at—2 to—3 C (28 to 26 F), 101 of 121 clones which have been bred specifically for frost resistance survived to at least—5 C (23 F) and some crosses resisted—9 C (16 F) without observable foliar damage. This suggests the possibility of obtaining cultivated varieties from varietal parents of cultivated species such as G. Andigena, G. Phureja, G. Stenotomum,S. ajanhuiri, and others, which are reasonably frost resistant.     

Recognition of host immune activation by Pseudomonas aeruginosa

It is generally reasoned that lethal infections caused by opportunistic pathogens develop permissively by invading a host that is both physiologically stressed and immunologically compromised. However, an alternative hypothesis might be that opportunistic pathogens actively sense alterations in host immune function and respond by enhancing their virulence phenotype. We demonstrate that interferon-gamma binds to an outer membrane protein in Pseudomonas aeruginosa, OprF, resulting in the expression of a quorum-sensing dependent virulence determinant, the PA-I lectin. These observations provide details of the mechanisms by which prokaryotic organisms are directly signaled by immune activation in their eukaryotic host.     

Immunological aspects of mammary tumors in dogs and cats: a survey including own studies and pertinent literature

Naturally occurring cancer in companion animals parallels cancer in man more closely than does experimentally induced cancer in inbred laboratory animals. In dogs and cats, as in man, a role for immune responses is indicated in the development of tumors. A survey is presented based on the literature and our own studies concerning the immunological and immunotherapeutic aspects of canine and feline mammary neoplasia. In dogs bearing mammary neoplasms, circulating immune complexes appear to play a negative role in the generation of effective antitumor immune responses. The functional role of peripheral blood lymphocytes and tumor-infiltrating lymphocytes in dogs and cats with mammary tumors is not yet fully established. No tumor antigen responsible for humoral or cellular responses has yet been identified. Extracorporeal perfusion of serum of dogs with mammary tumors and subcutaneous administration of mitomycin- and neuraminidase-treated autologous tumor cells are associated with improved prognosis. The opposite was true for i.v. treatment with BCG or Corynebacterium parvum vaccine in our study, in contrast to a previous report. A number of other treatment modalities in cats and dogs with mammary carcinomas failed to induce tumor regression. Canine and feline mammary carcinomas are good candidates for modern immunotherapeutic approaches.     

Genetic analysis of Mexican hairless pig populations.

The main Creole pig population in Mexico, the hairless Mexican pig, remains as an unimproved and endangered genetic resource. In order to learn more about the genetic characteristics of this pig population, we assessed the allele frequency of 10 microsatellite loci in 177 unrelated hairless pigs from seven regions at Mexico and in 111 pigs of four commercial breeds (Landrace, Large White, Hampshire, and Duroc). Genetic diversity in each population was estimated by the unbiased average heterozygosity and the allele number. Nei's standard genetic distances and a neighbor-joining dendrogram were used to reveal the genetic relationships among these populations. In this report, we present data showing that the level of the genetic diversity in Mexican hairless pigs is high compared with previous reports, and that they belong to a genetic lineage divergent from commercial breeds. Furthermore, Mexican hairless pigs seem to have developed several genetically distinct lines associated with their geographic location. We conclude that the Mexican Creole pig populations may be a reservoir of genetic diversity that is important to preserve and evaluate as a source of new alleles for the future improvement of commercial pig lines.     

OCT4 Expression in Outgrowth Colonies Derived from Porcine Inner Cell Masses and Epiblasts

The present study was conducted to test different methods for porcine inner cell mass (ICM) and epiblast isolation and to evaluate the morphology and expression of pluripotency genes in ICM‐ and epiblast‐derived outgrowth colonies (OCs) and passages thereof with particular attention on the relationship between OCT4 expression and embryonic stem cell (ESC)‐like morphology. A total of 104 zona pellucida‐enclosed and 101 hatched blastocysts were subjected to four different methods of ICM and epiblast isolation, respectively: Manual isolation, immunosurgery, immunosurgery with manual cleaning, or whole blastocyst culture. OCs were established on mouse embryonic fibroblast (MEF) cells and categorized according to morphology and OCT4 staining. Although all isolation methods resulted in ESC‐like OCs, immunosurgery with manual cleaning yielded significantly higher rates of ICM/epiblast attachment and subsequent ESC‐like morphology, whereas no significant difference was found between ICM and epiblasts with respect to these characteristics. All ESC‐like OCs showed nuclear OCT4 staining and expression of OCT4, NANOG and SOX2 as evaluated by RT‐PCR. Upon initial passages, the expression of pluripotency markers was, however, gradually lost in spite of maintained ESC‐like morphology. In conclusion, we have established a robust system for derivation of ESC‐like OCs from porcine ICM and epiblasts and we have shown that localization of OCT4 is associated with an ESC‐like morphology although this relationship is lost during early passages.     

Changes in muscle collagen content during <Emphasis Type="Italic">post mortem</Emphasis> storage of farmed sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>): influence on textural properties

The changes in collagen content and its solubility in sea bream muscle were studied for variable storage times following the death of the fish, and these variables were related to the evolution of physical parameters important for consumer acceptance: firmness and water-holding capacity (WHC). The results show that the collagen content in muscle diminished slightly over storage time and that this variable was directly related to firmness but inversely related to the water-holding capacity. With regard to collagen solubility, a decline was detected in acid-soluble collagen (ASC) in the first few post mortem hours, perhaps related to the end of rigor mortis that occurs at these stages. Pepsin-soluble collagen (PSC) increased, while insoluble collagen (ISC) decreased from 96 h, coinciding with a loss of firmness. This softening can be explained as a result of specific collagenases acting on the insoluble fraction of the collagen.     

The effect of exogenous hormonal treatment on egg quality of Chilean flounder (Paralichthys adspersus)

In this study, the effects of hormonal treatments on egg mortality after fertilization in Chilean flounder were evaluated. In the control group, plasmatic estradiol-17β showed very low levels before spawning induction. However E₂, GnRHa and GnRHa/bGH treatments caused high plasma E₂ levels resulted in poor egg survival. Probably, the persistent high E₂ levels affected the timing of oocyte maturation.