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.     

HUNTING METHODS AND CHOICE OF PREY OF GYRFALCONS FALCO RUSTICOLUS AT MVTN IN NORTHEAST ICELAND

Gyrfalcons breeding near Myvatn in northeast Iceland were studied from 1960 until 1970. Hunting methods and successful attacks are described. The Gyrfalcon usually hunts low over the ground and tries to surprise and flush its victim and then stoop upon it. If this fails, it may pursue. The choice of prey was studied by observations from mid-May to September of Gyrfalcons carrying prey, and by examining food-remains at eyries. Ducks and Ptarmigan comprised about 49% and 41 % respectively by number of individuals, and 62% and 35 % by estimated fresh weight. One pair utilised some 88 kg of food to raise foui young. The proportion of Ptarmigan in the diet increased during the study, reflecting the increase of the Ptarmigan population and suggesting that Ptarmigan are the preferred prey since waterfowl were abundant all the time.     

THE POWER OF SENSORY DISCRIMINATION METHODS USED IN REPLICATED DIFFERENCE AND PREFERENCE TESTS

Research on the power of discrimination methods in difference and preference tests has both theoretical and practical significance. Power is important to evaluate the sensitivities of tests and determine sample size. Ennis and Bi (1998, 1999) proposed the beta-binomial distribution to model replicated difference and preference tests with inter-trial variation and analyzed in general the power of the tests. In this paper, the power of discrimination methods for replicated difference and preference tests is discussed further. The equations for calculating power for methods based on the BB model are given. Examples with tables and charts for calculating and comparing the power of the methods are also given.     

IN VIVO MEASUREMENT OF ACTIVE OXYGEN PRODUCTION IN THE BROWN ALGA FUCUS EVANESCENS USING 2′,7′-DICHLOROHYDROFLUORESCEIN DIACETATE1

Intracellular production of active oxygen in the brown alga Fucus evanescens C. Ag. was studied by measuring the capacity for in vivo conversion of 2′,7′-dichlorohydrofluorescein diacetate (DCFH-DA) to the fluorescent dye 2′,7′-dichlorofluorescein (DCF), both in emersed and immersed seaweeds. Algae were incubated in seawater containing DCFH-DA under a range of conditions, and it was also possible to load algae with DCFH-DA and then follow subsequent DCF production in emersed tissue. DCF formation was linear for at least 2 h in both darkness and light, with the rate of formation increasing with the light level. DCF formation was temperature dependent. It also increased when algae were treated with H₂O₂ or methyl viologen (paraquat), which disrupts photosystem 1 electron transport and increases O^?₂ production. Exogenous catalase reduced in vivo DCF production, presumably by lowering cellular concentrations of H₂O₂. Hydrogen peroxide was released into the seawater by illuminated algae resulting in external dye conversion to DCF. However, this does not interfere with in vivo measurement of DCF by loaded, washed algae because DCF leakage appeared to be negligible. Internal DCF did not affect photosynthetic oxygen production relative to untreated controls. Overall, our data suggest that DCFH-DA is a potentially very useful probe for studying active oxygen metabolism in seaweeds subjected to environmental stresses.     

VARIATION IN THE STRENGTH OF MALE MATE CHOICE ALLOWS LONG‐TERM COEXISTENCE OF SPERM‐DEPENDENT ASEXUALS AND THEIR SEXUAL HOSTS

In several asexual taxa, reproduction requires mating with related sexual species to stimulate egg development, even though genetic material is not incorporated from the sexuals (gynogenesis). In cases in which gynogens do not invest in male function, they can potentially have a twofold competitive advantage over sexuals because the asexuals avoid the cost of producing males. If unmitigated, however, the competitive success of the asexuals would ultimately lead to their own demise, following the extinction of the sexual species that stimulate egg development. We have studied a model of mate choice among sexual individuals and asexual gynogens, where males of the sexual species preferentially mate with sexual females over gynogenetic females, to determine if such mating preferences can stably maintain both gynogenetic and sexual individuals within a community. Our model shows that stable coexistence of gynogens and their sexual hosts can occur when there is variation among males in the degree of preference for mating with sexual females and when pickier males pay a higher cost of preference.     

Activation of the l,d‐transpeptidation peptidoglycan cross‐linking pathway by a metallo‐d,d‐carboxypeptidase in Enterococcus faecium

Bypass of the penicillin‐binding proteins by an l ,d ‐transpeptidase (Ldt_fm) confers cross‐resistance to β‐lactam and glycopeptide antibiotics in mutants of Enterococcus faecium selected in vitro. Ldt_fm is produced by the parental strain D344S although it insignificantly contributes to peptidoglycan cross‐linking as pentapeptide stems cannot be used as acyl donors by this enzyme. Here we show that production of the tetrapeptide substrate of Ldt_fm is controlled by a two‐component regulatory system (DdcRS) and a metallo‐d ,d ‐carboxypeptidase (DdcY). The locus was silent in D344S and its activation was due to amino acid substitutions in DdcS or DdcR that led to production of DdcY and hydrolysis of the C‐terminal d ‐Ala residue of the cytoplasmic peptidoglycan precursor UDP‐MurNAc‐pentapeptide. The T¹⁶¹A and T¹⁶¹M substitutions affected a position of DdcS known to be essential for the phosphatase activity of related sensor kinases. Complete elimination of UDP‐MurNAc‐pentapeptide, which was required specifically for resistance to glycopeptides, involved substitutions in DdcY that increased the catalytic efficiency of the enzyme (E¹²⁷K) and affected its interaction with the cell envelope (I¹⁴N). The ddc locus displays striking similarities with portions of the van vancomycin resistance gene clusters, suggesting possible routes of emergence of cross‐resistance to glycopeptides and β‐lactams in natural conditions.     

DECOUPLING OF SHORT‐ AND LONG‐DISTANCE DISPERSAL PATHWAYS IN THE ENDEMIC NEW ZEALAND SEAWEED CARPOPHYLLUM MASCHALOCARPUM (PHAEOPHYCEAE,FUCALES)1

The processes that produce and maintain genetic structure in organisms operate at different timescales and on different life‐history stages. In marine macroalgae, gene flow occurs through gamete/zygote dispersal and rafting by adult thalli. Population genetic patterns arise from this contemporary gene flow interacting with historical processes. We analyzed spatial patterns of mitochondrial DNA variation to investigate contemporary and historical dispersal patterns in the New Zealand endemic fucalean brown alga Carpophyllum maschalocarpum (Turner) Grev. Populations bounded by habitat discontinuities were often strongly differentiated from adjoining populations over scales of tens of kilometers and intrapopulation diversity was generally low, except for one region of northeast New Zealand (the Bay of Plenty). There was evidence of strong connectivity between the northern and eastern regions of New Zealand’s North Island and between the North and South Islands of New Zealand and the Chatham Islands (separated by 650 km of open ocean). Moderate haplotypic diversity was found in Chatham Islands populations, while other southern populations showed low diversity consistent with Last Glacial Maximum (LGM) retreat and subsequent recolonization. We suggest that ocean current patterns and prevailing westerly winds facilitate long‐distance dispersal by floating adult thalli, decoupling genetic differentiation of Chatham Island populations from dispersal potential at the gamete/zygote stage. This study highlights the importance of encompassing the entire range of a species when inferring dispersal patterns from genetic differentiation, as realized dispersal distances can be contingent on local or regional oceanographic and historical processes.     

Organocatalyzed Domino Synthesis of New Thiazole‐Based Decahydroacridine‐1,8‐diones and Dihydropyrido[2,3‐d : 6,5‐d′]‐ dipyrimidines in Water as Antimicrobial Agents

Organopromoter, 2‐aminoethanesulfonic acid was used to catalyze the synthesis of a series of structurally intriguing new hybrids thiazolyl acridine‐1,8(2H,5H)‐diones and dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,5H,7H)‐tetraones for the first time. 2‐Aminoethanesulfonic acid is a biobased organopromoter, used to generate four new bonds for the synthesis of new coupled thiazole‐based decahydroacridine‐1,8‐diones. Superior green credentials, operational simplicity, easy work‐up and recyclability of the catalyst are the key strengths of this method. The broad substrate scope, mild reaction conditions, short reaction time, cost effectiveness, high atom economy and good to excellent yields make the present method a distinct improvement over existing methods. Spectral (IR, ¹H‐NMR,¹³C‐NMR, Mass) data and elemental analyses confirmed the structures of the titled products. A series of thiazolyl acridine‐1,8(2H,5H)‐diones and dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,5H,7H)‐tetraones were screened for their antimicrobial activity against four bacterial and three fungal strains.     

INGESTION AND EXPECTORATION SAMPLING METHODS OF FOUR TASTES IN A MODEL SYSTEM USING TIME-INTENSITY EVALUATIONS

The objective of this investigation was to compare two sampling methods (expectoration and ingestion) of single component water solutions (sweet—5% sucrose, sour—0.006% citric acid, bitter—0.027% caffeine, salty—0.325% sodium chloride) using time-intensity (T-I) evaluations. Analysis of variance was used to evaluate significant differences. There were subject inconsistencies for the recording times (RT) of sucrose, caffeine and sodium chloride tastes among the sampling methods. No panel differences were found for citric acid duration (RT) between ingested or expectorated samples. Individual contradictions for amplitude sucrose and sodium chloride mixtures were apparent however, the panel demonstrated no differences among the amplitude means between the sampling methods for citric acid and caffeine solutions. Aftertastes for ingested sodium chloride solutions were significantly (P < 0.01) greater than for expectorated samples whereas sampling techniques had no effect upon caffeine aftertastes. Individual contradictions were apparent for citric acid and sucrose aftertastes between the sampling methods.     

NONSTATIONARY PATTERNS OF ISOLATION‐BY‐DISTANCE: INFERRING MEASURES OF LOCAL GENETIC DIFFERENTIATION WITH BAYESIAN KRIGING

Patterns of isolation‐by‐distance (IBD) arise when population differentiation increases with increasing geographic distances. Patterns of IBD are usually caused by local spatial dispersal, which explains why differences of allele frequencies between populations accumulate with distance. However, spatial variations of demographic parameters such as migration rate or population density can generate nonstationary patterns of IBD where the rate at which genetic differentiation accumulates varies across space. To characterize nonstationary patterns of IBD, we infer local genetic differentiation based on Bayesian kriging. Local genetic differentiation for a sampled population is defined as the average genetic differentiation between the sampled population and fictive neighboring populations. To avoid defining populations in advance, the method can also be applied at the scale of individuals making it relevant for landscape genetics. Inference of local genetic differentiation relies on a matrix of pairwise similarity or dissimilarity between populations or individuals such as matrices of between pairs of populations. Simulation studies show that maps of local genetic differentiation can reveal barriers to gene flow but also other patterns such as continuous variations of gene flow across habitat. The potential of the method is illustrated with two datasets: single nucleotide polymorphisms from human Swedish populations and dominant markers for alpine plant species.     

IDENTIFICATION OF CROSS‐FERTILIZED CONCHOCELIS USING CLEAVED AMPLIFIED POLYMORPHIC SEQUENCE MARKERS IN CROSS‐EXPERIMENTS OF PORPHYRA YEZOENSIS (BANGIALES,RHODOPHYTA)1

As a part of the construction of a Porphyra yezoensis Ueda genetic linkage map, we conducted intraspecific cross‐experiments and subsequent screening of cross‐fertilized conchocelis by cleaved amplified polymorphic sequence (CAPS) analysis. The cross‐experiments were carried out between males of the wildtype (KGJ) and females of the recessive green mutant (TU‐2) using two methods, controlled and random crosses. A total of 42 and 186 wildtype‐colored conchocelis colonies were obtained from the former and latter experiments, respectively. Among those, 49 DNA samples (14% and 23% obtained from the former and latter crosses, respectively) showed biparental CAPS patterns in the two gene regions (EF‐1α open reading frame [ORF] region and V‐ATPase). This study represents the first report in which the cross‐fertilized conchocelis of P. yezoensis has been directly confirmed by molecular marker. The combination of the simple DNA extraction and CAPS analysis may be applicable in genetic studies of other macroalgae that are monoecious and/or grow slowly in laboratory culture.     

X‐AUTOSOME INCOMPATIBILITIES IN DROSOPHILA MELANOGASTER: TESTS OF HALDANE'S RULE AND GEOGRAPHIC PATTERNS WITHIN SPECIES

Substantial genetic variation exists in natural populations of Drosophila melanogaster. This segregating variation includes alleles at different loci that interact to cause lethality or sterility (synthetic incompatibilities). Fitness epistasis in natural populations has important implications for speciation and the rate of adaptive evolution. To assess the prevalence of epistatic fitness interactions, we placed naturally occurring X chromosomes into genetic backgrounds derived from different geographic locations. Considerable amounts of synthetic incompatibilities were observed between X chromosomes and autosomes: greater than 44% of all combinations were either lethal or sterile. Sex‐specific lethality and sterility were also tested to determine whether Haldane's rule holds for within‐species variation. Surprisingly, we observed an excess of female sterility in genotypes that were homozygous, but not heterozygous, for the X chromosome. The recessive nature of these incompatibilities is similar to that predicted for incompatibilities underlying Haldane's rule. Our study also found higher levels of sterility and lethality for genomes that contain chromosomes from different geographical regions. These findings are consistent with the view that genomes are coadapted gene complexes and that geography affects the likelihood of epistatic fitness interactions.     

Substrate and metabolic promiscuities of d‐altronate dehydratase family proteins involved in non‐phosphorylative d‐arabinose,sugar acid,l‐galactose and l‐fucose pathways from bacteria

The gene context in microorganism genomes is of considerable help for identifying potential substrates. The C785_RS13685 gene in Herbaspirillum huttiense IAM 15032 is a member of the d‐ altronate dehydratase protein family, and which functions as a d‐ arabinonate dehydratase in vitro, is clustered with genes related to putative pentose metabolism. In the present study, further biochemical characterization and gene expression analyses revealed that l‐ xylonate is a physiological substrate that is ultimately converted to α‐ketoglutarate via so‐called Route II of a non‐phosphorylative pathway. Several hexonates, including d‐ altronate, d‐ idonate and l‐ gluconate, which are also substrates of C785_RS13685, also significantly up‐regulated the gene cluster containing C785_RS13685, suggesting a possibility that pyruvate and d‐ or l‐ glycerate were ultimately produced (novel Route III). On the contrary, ACAV_RS08155 of Acidovorax avenae ATCC 19860, a homologous gene to C785_RS13685, functioned as a d‐ altronate dehydratase in a novel l‐ galactose pathway, through which l‐ galactonate was epimerized at the C5 position by the sequential activity of two dehydrogenases, resulting in d‐ altronate. Furthermore, this pathway completely overlapped with Route III of the non‐phosphorylative l‐ fucose pathway. The ‘substrate promiscuity’ of d‐ altronate dehydratase protein(s) is significantly expanded to ‘metabolic promiscuity’ in the d‐ arabinose, sugar acid, l‐ fucose and l‐ galactose pathways.