Ploidy level manipulations in potato through sexual hybridisation

There is no better use of sexual reproduction in regard to breeding and genetic research than the ploidy level manipulations possible in the potato and its relatives. Unique reproductive characteristics of tuber‐bearing Solanum species make possible: the production of gametes with unreduced chromosome number; the presence of an endosperm dosage system that regulates success of interploidy/interspecific crosses; the possibility to easily extract maternal haploids following crosses with S. phureja. This paper reviews results obtained in scaling genomic multiples up and down in potato, and relates these manipulations to breeding strategies for the genetic improvement of the cultivated potato. Several ploidy series have been developed, ranging from the monoploid to the hexaploid level. Cultivated tetraploids were scaled down to the diploid and monoploid level by haploidy. Scaling upward was achieved by sexual polyploidisation via 2n gametes that resulted in triploid, tetraploid, pentaploid, and hexaploid genotypes with a broad genetic base. Altogether, the success of ploidy level manipulations constitutes further proof that sexual polyploidisation played an important role in the polyploid evolution of Solanum species, and supports the idea that gene flow can be relatively easily accomplished through interploid and bridge crosses.     

Primers and polymerase chain reaction conditions for DNA barcoding teleost fish based on the mitochondrial cytochrome b and nuclear rhodopsin genes

This report describes a set of 21 polymerase chain reaction primers and amplification conditions developed to barcode practically any teleost fish species according to their mitochondrial cytochrome b and nuclear rhodopsin gene sequences. The method was successfully tested in more than 200 marine fish species comprising the main Actinopterygii family groups. When used in phylogenetic analyses, its combination of two genes with different evolutionary rates serves to identify fish at the species level. We provide a flow diagram indicating our validated polymerase chain reaction amplification conditions for barcoding and species identification applications as well as population structure or haplotyping analyses, adaptable to high‐throughput analyses.     

Inhibiting aphid wing development: is immune challenge important?

Aphids show inhibition of wing development when parasitized by hymenopteran parasitoids, especially when parasitism takes place early in the host's development. The present study tests the hypothesis that the aphid itself redirects the resources needed for the development of wings to support the immune response, rather than the parasitoid directly promoting wing inhibition. When the aphid's immune system is challenged with bacterial antigens and a fungal pathogen, neither immune challenge alters wing development, indicating that perhaps there is no redirection by the aphid of resources required for wing development to cover possible costs of mounting an immune response.     

The Ultrastructure of Ion-Secreting and Non-Secreting Salt Glands of Limonium platyphyllum

The ultrastructure of salt glands in developing leaves of Limoniumplatyphyllum is described prior to exposure to 3% NaCl solution(with non-secreting glands) and after 4.5 and 18 h exposureto the salt solution. It is shown that in most glands, the transitionto active chloride transport was accompanied by the displacementof vacuoles toward the cell periphery and by the establishmentof plasmalemma contact sites with the tonoplast which appearedsimilar to gap junctions in animal epithelial cells. No evidencefor the exocytosis of vacuoles was found. It is suggested thatgland vacuoles may have a primary role in chloride secretionand that the tonoplast may be functionally asymmetrical, sothat the free part facing the hyaloplasm bears ion pumps, whereashighly permeable ion channels are active along the zone of contactwith the plasmalemma. It follows that the active step in chloridetransport in Limonium glands is the influx of ions into thevacuoles. Within the inner cup cells of the gland, vacuolescome into contact with the plasmalemma only at sites where thecell wall is adjacent to secretory and accessory cells. Suchan asymmetry appears to ensure the directed flux of ions intothis cell wall. Wall protuberances in the gland cells are rudimentaryand presumably not involved directly in NaCl secretion. Thenucleolus is activated during secretion and the frequency offree ribosomes is significantly increased, which is suggestiveof their involvement in the synthesis of membrane transportproteins. The ultrastructure of about one-third of the glandsremained unchanged in salt-treated leaves. Key words: Salt glands, ultrastructure, ion fluxes     

POTENCY OF SWEETNESS OF ASPARTAME, D-TRYPTOPHAN AND THAUMATIN EVALUATED BY SINGLE VALUE AND TIME-INTENSITY MEASUREMENTS

Perceived sweetness of sucrose, aspartame, D-tryptophan and thaumatin in a sour, citric acid background was analyzed in terms of the potency of these compounds relative to sucrose-water combinations. Potencies of the sweeteners were determined from (1) maximum intensity using single value and time-intensity (T-I) measurements and (2) average intensity calculated as the ratio of area under the T-I curve and total perceived time. Stevens' law was applied to sweet responses, either in static or dynamic conditions. It was found that the exponent of the concentration-response function reflected the relative capacity of a compound to sweeten a given food and stressed differences of potency among sweeteners. Aspartame, D-tryptophan and thaumatin exhibited a decrease in sweetness potency relative to sucrose as sweetness increased from 10 to 100% of the full scale of response. Across the entire sweetness range, thaumatin showed the greatest potency but its long persistence time led to differentiate this intense sweetener from the other sweeteners evaluated.     

A complex marine shallow-water boring trace: Dendrorete balani n. ichnogen. et ichnospec

Tavernier, A., Campbell. S. E. & Golubic, S. 1992 07 15: A complex marine shallow-water boring trace: Dendrorete balani n. ichnogen. et ichnospec.
Exceptionally well-preserved reticulate boring patterns in Pliocene barnacle shells are described as a new ichnogenus and species. The organism that formed these borings is a presumed phototroph, possibly belonging to green algae. The principles and needs of a taxonomic treatment of microborings as trace fossils in relation to that of their makers are discussed. It is suggested that ichno-taxonomy be extended to include modern traces, when the taxonomic identity of the agent cannot be ascertained. Bio-erosion, endoliths, ichnofossils, marine, microborings, shallow marine, shells .     

A COMPARISON OF METHODS FOR MONITORING INDIVIDUAL PERFORMANCES IN TASTE SELECTION TESTS

The evaluation of panel performance was made by three methods: average of correct responses (A), comparison of distances of individual standardized judgments to the average standardized responses (D) and a principal components analysis (PCA). Thirty assessors identified water and basic tastes and discriminated different sweet stimuli in neutral or acidified vehicles using R‐index rating and ranking tests. By A and D methods 22 assessors were qualified as proficient. Composition of both panels was identical except for one judge. The output from PCA provided a graphical representation of the performance of the assessors and retained different subsets of 24–26 panelists for different proposals as discrimination of sweetness in acidified beverages, recognition of bitterness, sourness and discrimination of slight sweetness or evaluation of saltiness.     

EFFECTS OF SAMPLING CONDITIONS ON TEMPORAL PERCEPTION OF BITTERNESS IN YERBA MATE (ILEX PARAGUARIENSIS) INFUSIONS

Time-intensity (TI) methodology and a trained panel were used to characterize the perceived bitterness of Yerba mate (YM) Ilex paraguariensis infusions. Two sampling procedures (sip and spit; sip and swallow) and two conditions for residence time in mouth (free or fixed duration of 5 s until spit or swallow) were evaluated.
At a fixed duration the maximum bitterness as well as the time to reach it showed a significant YM concentration dependence. No change on bitterness was observed by swallowing or spitting YM infusions except a larger rate of decay of the response (v_r) at spit condition. Dynamic bitterness at free sampling time showed that the decision period to spit or swallow the YM infusion approximately duplicated the fixed one of 5 s.