An experimental study on the self-reference effect

Self-reference at encoding increases the probability of recollective experience in recognition memory. Self-reference effect (SRE) in memory is observed when the degree of self-reference of to-be-remembered materials is varied. Usually items encoded in terms of self-reference are associated with significantly higher recall performance relative to items encoded in other ways, including semantic encoding. In our three experiments, four orientating tasks formed four levels in a between-subjects design. The conditions were rating personality traits with reference to self, mother, Lu Xun (a famous Chinese writer) or rating the traits on a negative-positive dimension. In a recognition test, subjects first identified old items and then indicated which of these were accompanied by recollective experience ('remember' responses) and which were recognized on some other basis ('know' responses). Our results showed that both the self-reference condition and mother condition were associated with the same highest propo     

Subtle ‘boom and bust’ response of <Emphasis Type="Italic">Macquaria ambigua</Emphasis> to flooding in an Australian dryland river

The ecology of dryland rivers is driven by their highly variable hydrology, particularly flooding regimes, whereby intermittent floods typically generate ‘booms’ of primary and secondary productivity, including massive fish production. We tested these concepts in the Moonie River, Australia, using the percichthyid, Macquaria ambigua, a dryland river species known to display pronounced ‘boom and bust’ abundance patterns in response to floodplain inundation followed by extended periods of low to no channel flow. We expected that body condition (as measured by whole body lipid content) and biomass of M. ambigua would be related to prey biomass, and that these factors would all ‘spike’ following widespread flooding. Instead we found more subtle responses. There were ‘booms’ in biomass of Macrobrachium and zooplankton, two important food items, whereas M. ambigua maintained relatively low but sustained lipid and biomass levels following flooding. It appears that instead of a ‘boom’ in fish biomass, abundant invertebrate food resources and sustained lipid levels contributed to high survivorship of this species during the ‘bust’ period over cool dry months.     

Redundant information encoding in primary motor cortex during natural and prosthetic motor control

Redundant encoding of information facilitates reliable distributed information processing. To explore this hypothesis in the motor system, we applied concepts from information theory to quantify the redundancy of movement-related information encoded in the macaque primary motor cortex (M1) during natural and neuroprosthetic control. Two macaque monkeys were trained to perform a delay center-out reaching task controlling a computer cursor under natural arm movement (manual control, ‘MC’), and using a brain-machine interface (BMI) via volitional control of neural ensemble activity (brain control, ‘BC’). During MC, we found neurons in contralateral M1 to contain higher and more redundant information about target direction than ipsilateral M1 neurons, consistent with the laterality of movement control. During BC, we found that the M1 neurons directly incorporated into the BMI (‘direct’ neurons) contained the highest and most redundant target information compared to neurons that were not incorporated into the BMI (‘indirect’ neurons). This effect was even more significant when comparing to M1 neurons of the opposite hemisphere. Interestingly, when we retrained the BMI to use ipsilateral M1 activity, we found that these neurons were more redundant and contained higher information than contralateral M1 neurons, even though ensembles from this hemisphere were previously less redundant during natural arm movement. These results indicate that ensembles most associated to movement contain highest redundancy and information encoding, which suggests a role for redundancy in proficient natural and prosthetic motor control.     

Time and Encoding Effects in the Concealed Knowledge Test

Although the traditional “lie detector” test is used frequently in forensic contexts, it has (like most test of deception) some limitations. The concealed knowledge test (CKT) focuses on participants’ recognition of privileged knowledge rather than lying per-se and has been studied extensively using a variety of measures. A “guilty” suspect’s interaction with and memory of crimescene items may vary. Furthermore, memory for crimescene items may diminish over time. The interaction of encoding quality and test delay on CKT efficiency has been previously implied, but not yet demonstrated. We used a response-time based CKT to detect concealed knowledge from shallow and deep study procedures after 10-min, 24-h, and 1-week delays. Results show that more elaborately encoded information afforded higher detection accuracy than poorly encoded items. Although classification accuracy following deep study was unaffected by delay, detection of poorly elaborated information was initially high, but compromised after 1 week. Thus, choosing optimal test items requires considering both test delay and initial encoding level.     

The genetic control of milling yield, dough rheology and baking quality of wheat

Improving the end-use quality of wheat is a key target for many breeding programmes. With the exception of the relationship between glutenin alleles and some dough rheological characters, knowledge concerning the genetic control of wheat quality traits is somewhat limited. A doubled haploid population produced from a cross between two Australian cultivars ‘Trident’ and ‘Molineux’ has been used to construct a linkage map based largely on microsatellite molecular makers. ‘Molineux’ is superior to ‘Trident’ for a number of milling, dough rheology and baking quality characteristics, although by international standards ‘Trident’ would still be regarded as possessing moderately good end-use quality. This population was therefore deemed useful for investigation of wheat end-use quality. A number of significant QTL identified for dough rheological traits mapped to HMW and LMW glutenin loci on chromosomes 1A and 1B. However, QTL associated with dough strength and loaf volume were also identified on chromosome 2A and a significant QTL associated with loaf volume and crumb quality was identified on chromosome 3A. A QTL for flour protein content and milling yield was identified on chromosome 6A and a QTL associated with flour colour reported previously on chromosome 7B was confirmed in this population. The detection of loci affecting dough strength, loaf volume and flour protein content may provide fresh opportunities for the application of marker-assisted selection to improve bread-making quality.     

Genetic dissection of root growth in rice (Oryza sativa L.) I: a hydrophonic screen

 Root growth is an important component of the adaptation of rice to drought-prone environments. A hydroponic screen was used to study root growth of 28 rice varieties. Both maximum root length and adventitious root thickness varied widely between varieties. In general, japonica varieties had larger root systems than indica varieties. Two F₂ populations involving the thick- and long-rooted upland japonica variety ‘Azucena’ and two poor-rooting varieties, namely the upland indica‘Bala’ and the Italian japonica‘Maratelli’, were made and screened in hydroponics. Generation means analysis revealed significant additive and dominance main effects for the root length traits with a prevalence of dominance gene effects in both crosses. The dominance×dominance type of non-allelic interactions were important for maximum root length from day 7 to day 28, root volume, root thickness and root cell length in the cross ‘Bala’בAzucena’. The heritability (broad-sense) estimates varied from low to high for the traits and displayed differences between populations. This suggested that recombinant lines with improved root traits can be developed from the two crosses with selection methods that involve some form of progeny evaluation. In a companion paper, we report the mapping of quantitative trait loci (QTLs) for root growth traits in the ‘Bala’בAzucena’ population using restriction fragment length polymorphisms (RFLPs). Received: 5 May 1996 / Accepted: 14 February 1997     

In vitro screening for burrowing nematode, Radopholus citrophilus, tolerance and resistance in commercial Anthurium hybrids

Summary A reliable method to screen Anthurium for burrowing nematode resistance and tolerance in vitro was developed using 17 genetically distinct Anthurium cultivars. Based on nonparametric data analysis, tolerance and resistance were found to be independent traits to be evaluated separately. An effective parameter for tolerance evaluation was ranking of relative leaf retention, whereas an effective parameter for resistance evaluation was the ranking of nematode reproduction, log(Rf+1). A comparison of the ranking of leaf retention with ranking of nematode reproduction clustered the cultivar responses to burrowing nematode infection into four groups: intolerant and resistant, moderately tolerant but susceptible, intolerant and susceptible, and tolerant and susceptible. ‘Ozaki’ was identified as an intolerant reference, ‘Nitta’ as a susceptible reference. ‘Blushing Bride’ was the most tolerant cultivar among those screened, but it may not be an ideal tolerant reference due to its low vigor. Future screening for burrowing nematode-tolerant and-resistant cultivars in Anthurium should include ‘Ozaki’ and ‘Nitta’ as internal controls. Evaluation of resistance should be based on a resistance index obtained by log(Rf of hybrid tested +1) divided by log(Rf of ‘Nitta’ +1); tolerance should be based on ranking of relative leaf retention.     

Anatomical structure and gravitropic response of the creeping shoots of ground-cover chrysanthemum ‘Yuhuajinhua’

The chrysanthemum cultivar ‘Yuhuajinhua’ has a creeping habit. The anatomy and distribution of amyloplasts within ‘Yuhuajinhua’ stems were compared to those typical of non-creeping cultivars. ‘Yuhuajinhua’ stems are similar to those of conventional cultivars; but except for the pith, the proportion of the various tissues present in the upper side of stems was higher than that in the lower side. Most of the amyloplasts lie in the centre of the endodermal cells of the ‘Yuhuajinhua’ stems, rather than at the bottom, as is typical for non-creeping cultivars. When ‘Yuhuajinhua’ plants were oriented horizontally and kept in the dark, the stems retained their original growth direction, and the endodermis amyloplasts sedimented according to the gravitational direction. The endodermis amyloplasts responded rapidly to gravistimulation. The content of IAA in the upper side of the ‘Yuhuajinhua’ stems was higher than that in the lower side, associated with the assymetric growth of the stems.     

Relations of homology between higher cognitive emotions and basic emotions

In the last 10 years, several authors including Griffiths and Matthen have employed classificatory principles from biology to argue for a radical revision in the way that we individuate psychological traits. Arguing that the fundamental basis for classification of traits in biology is that of ‘homology’ (similarity due to common descent) rather than ‘analogy’, or ‘shared function’, and that psychological traits are a special case of biological traits, they maintain that psychological categories should be individuated primarily by relations of homology rather than in terms of shared function. This poses a direct challenge to the dominant philosophical view of how to define psychological categories, viz., ‘functionalism’. Although the implications of this position extend to all psychological traits, the debate has centered around ‘emotion’ as an example of a psychological category ripe for reinterpretation within this new framework of classification. I address arguments by Griffiths that emotions should be divided into at least two distinct classes, basic emotions and higher cognitive emotions, and that these two classes require radically different theories to explain them. Griffiths argues that while basic emotions in humans are homologous to the corresponding states in other animals, higher cognitive emotions are dependent on mental capacities unique to humans, and are therefore not homologous to basic emotions. Using the example of shame, I argue that (a) many emotions that are commonly classified as being higher cognitive emotions actually correspond to certain basic emotions, and that (b) the “higher cognitive forms” of these emotions are best seen as being homologous to their basic forms.     

Characteristics of Human Luminance Discrimination and Modeling a Neural Network Based on the Response Properties of the Visual Cortex

Reaction time (RT) and error rate that depend on stimulus duration were measured in a luminance-discrimination reaction time task. Two patches of light with different luminance were presented to participants for ‘short’ (150 ms) or ‘long’ (1 s) period on each trial. When the stimulus duration was ‘short’, the participants responded more rapidly with poorer discrimination performance than they did in the longer duration. The results suggested that different sensory responses in the visual cortices were responsible for the dependence of response speed and accuracy on the stimulus duration during the luminance-discrimination reaction time task. It was shown that the simple winner-take-all-type neural network model receiving transient and sustained stimulus information from the primary visual cortex successfully reproduced RT distributions for correct responses and error rates. Moreover, temporal spike sequences obtained from the model network closely resembled to the neural activity in the monkey prefrontal or parietal area during other visual decision tasks such as motion discrimination and oddball detection tasks.     

Development of a genetic linkage map and identification of homologous linkage groups in sweetpotato using multiple-dose AFLP markers

Sweetpotato genomic research is minimal compared to most other major crops despite its worldwide importance as a food crop. The development of a genetic linkage map in sweetpotato will provide valuable information about the genomic organization of this important species that can be used by breeders to accelerate the introgression of desired traits into breeding lines. We developed a mapping population consisting of 240 individuals of a cross between ‘Tanzania’, a cream-fleshed African landrace, and ‘Beauregard’, an orange-fleshed US sweetpotato cultivar. The genetic linkage map of this population was constructed using Amplified Fragment Length Polymorphism (AFLP) markers. A total of 1944 (‘Tanzania’) and 1751 (‘Beauregard’) AFLP markers, of which 1511 and 1303 were single-dose markers respectively, were scored. Framework maps consisting of 86 and 90 linkage groups for ‘Tanzania’ and ‘Beauregard’ respectively, were developed using a combination of JoinMap 3.0 and MAPMAKER/EXP 3.0. A total of 947 single-dose markers were placed in the final framework linkage map for ‘Tanzania’. The linkage map size was estimated as 5792 cM, with an average distance between markers of 4.5 cM. A total of 726 single-dose markers were placed in the final framework map for ‘Beauregard’. The linkage map length was estimated as 5276 cM, with an average distance between markers of 4.8 cM. Duplex and triple-dose markers were used to identify the corresponding homologous groups in the maps. Our research supports the hypothesis that sweetpotato is an autopolyploid. Distorted segregation in some markers of different dosages in this study suggests that some preferential pairing occurs in sweetpotato. However, strict allopolyploid inheritance in sweetpotato can be ruled out due to the observed segregation ratios of the markers, and the proportion of simplex to multiple-dose markers. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This paper is a portion of a dissertation submitted by Jim C. Cervantes-Flores.     

Casares’ map function: no need for a ‘corrected’ Haldane’s map function

A genetic map function M(d) = RF provides a mapping from the additive genetic distance d to the non-additive recombination fraction RF between a given pair of loci, where the recombination fraction is the proportion of gametes that are recombinant between the two loci. Genetic map functions are needed because in most experiments all we can directly observe are the recombination events. However, since a recombination event is only observed if there are an odd number of crossovers between the two loci, recombination fractions are not additive. One of the most widely used map functions is Haldane’s map function, which is derived under the assumptions of no chiasma and no chromatid interference, and has been in widespread use since 1919. However, Casares recently proposed a ‘corrected’ Haldane’s map function – we show here that this ‘corrected’ map function is not correct due to faulty assumptions and mistakes in its derivation.     

Construction of a dense genetic linkage map for apple rootstocks using SSRs developed from Malus ESTs and Pyrus genomic sequences

Marker-assisted selection (MAS) offers quick and reliable prediction of the phenotypes of seedlings in large populations and thus opens new approaches for selection to breeders of apple (Malus x domestica Borkh.). The development of framework maps enables the discovery of genetic markers linked to desired traits. Although genetic maps have been reported for apple scion cultivars, none has previously been constructed for apple rootstocks. We report the construction of framework genetic maps in a cross between ‘M.9’ (‘Malling 9’) and ‘R.5’ (‘Robusta 5’) apple rootstocks. The maps comprise 224 simple sequence repeat (SSR) markers, 18 sequence-characterised amplified regions, 14 single nucleotide polymorphisms and 42 random amplified polymorphic DNAs. A new set of 47 polymorphic SSRs was developed from apple EST sequences and used for construction of this rootstock map. All 17 linkage groups have been identified and aligned to existing apple genetic maps. The maps span 1,175.7 cM (‘M.9’) and 1,086.7 cM (‘R.5’). To improve the efficiency of mapping markers to this framework map, we developed a bin mapping set. Applications of these new genetic maps include the elucidation of the genetic basis of the dwarfing effect of the apple rootstock ‘M.9’ and the analysis of disease and insect resistance traits such as fire blight (Erwinia amylovora), apple scab (Venturia inaequalis) and woolly apple aphid (Eriosoma lanigerum). Markers for traits mapped in this population will be of direct use to apple breeders for MAS and for identification of causative genes by map-based cloning.     

An Overview of the Introns-First Theory

We review the introns-first hypothesis a decade after it was first proposed. It is that exons emerged from non-coding regions interspersed between RNA genes in an early RNA world, and is a subcomponent of a more general ‘RNA-continuity’ hypothesis. The latter is that some RNA-based systems, especially in RNA processing, are ‘relics’ that can be traced back either to the RNA world that preceded both DNA and encoded protein synthesis or to the later ribonucleoprotein (RNP) world (before DNA took over the main coding role). RNA-continuity is based on independent evidence—in particular, the relative inefficiency of RNA catalysis compared with protein catalysis—and leads to a wide range of predictions, ranging from the origin of the ribosome, the spliceosome, small nucleolar RNAs, RNases P and MRP, and mRNA, and it is consistent with the wide involvement of RNA-processing and regulation of RNA in modern eukaryotes. While there may still be cause to withhold judgement on intron origins, there is strong evidence against introns being uncommon in the last eukaryotic common ancestor (LECA), and expanding only within extant eukaryotic groups—the ‘very-late’ intron invasion model. Similarly, it is clear that there are selective forces on numbers and positions of introns; their existence may not always be neutral. There is still a range of viable alternatives, including introns first, early, and ‘latish’ (i.e. well established in LECA), and regardless of which is ultimately correct, it pays to separate out various questions and to focus on testing the predictions of sub-theories.     

Development of a wheat genotype combining the recessive crossability alleles kr1kr1kr2kr2 and the 1BL.1RS translocation, for the rapid enrichment of 1RS with new allelic variation

The main objective of the present work was to develop a wheat genotype containing both the recessive crossability alleles (kr1kr1kr2kr2), allowing high crossability between 6x wheat and diploid rye, and the 1BL.1RS wheat/rye translocation chromosome. This wheat genotype could be used as a recipient partner in wheat–rye crosses for the efficient introduction of new allelic variation into 1RS in translocation wheats. After crossing the wheat cultivars ‘Mv Magdaléna’ and ‘Mv Béres’, which carry the 1BL.1RS translocation involving the 1RS chromosome arm from ‘Petkus’, with the line ‘Mv9 kr1’, 117 F₂ plants were analysed for crossability, ten of which had higher than 50% seed set with rye and thus presumably carried the kr1kr1kr2kr2 alleles. Four of the ten plants contained the 1BL.1RS translocation in the disomic condition as detected by genomic in situ hybridization (GISH). The wheat × rye F₁ hybrids produced between these lines and the rye cultivar ‘Kriszta’ were analysed in meiosis using GISH. 1BL.1RS/1R chromosome pairing was detected in 62.4% of the pollen mother cells. The use of fluorescent in situ hybridization (FISH) with the repetitive DNA probes pSc119.2, Afa family and pTa71 allowed the 1R and 1BL.1RS chromosomes to be identified. The presence of the 1RS arm from ‘Kriszta’ besides that of ‘Petkus’ was demonstrated in the F₁ hybrids using the rye SSR markers RMS13 and SCM9. In four of the 22 BC₁ progenies analysed, only ‘Kriszta’-specific bands were observed with these markers, though the presence of the 1BL.1RS translocation was detected using GISH. It can be concluded that recombination occurred between the ‘Petkus’ and ‘Kriszta’ 1RS chromosome arms in the translocated chromosome in these plants.     

Influence of dent corn genetic backgrounds on QTL detection for plant-height traits and their relationships in high-oil maize

QTL mapping for plant-height traits has not been hitherto reported in high-oil maize. A high-oil maize inbred ‘GY220’ was crossed with two dent maize inbreds (‘8984’ and ‘8622’) to generate two connected F_2:3 populations. Four plant-height traits were evaluated in 284 and 265 F_2:3 families. Single-trait QTL mapping and multiple-trait joint QTL mapping was used to detect QTLs for the traits and the genetic relationship between plant height (PH) and two other plant-height traits. A total of 28 QTLs and 12 pairs of digenic interactions among detected QTLs for four traits were detected in the two F_2:3 families. Only one marker was shared between the two populations. Joint analysis of PH with ear height (EH) and PH with top height (TH) detected 32 additional QTLs. Our results showed that QTL detection for PH was dependent on the genetic background of dent corn inbreds. Multiple-trait joint QTL analysis could increase the number of detected QTLs.     

Stress-induced changes important for effective androgenic induction in isolated microspore culture of triticale (×<Emphasis Type="Italic">Triticosecale</Emphasis> Wittm.)

The accumulation of abscisic acid (ABA) and the activities of antioxidative enzymes along with cell metabolic activity were monitored during androgenesis induction in triticale (×Triticosecale Wittm.). Tested cultivars ‘Mieszko’ and ‘Wanad’ were selected due to their significantly different responses to androgenic induction. Significant variation was observed in respect of superoxide dismutase activity and endogenous ABA content in anthers isolated from freshly cut tillers. For both cultivars, tillers pretreatment with low temperature decreased peroxidase activity by 36%, highly accelerated respiration rate and reduced heat production. At the same time, the level of ABA in ‘Mieszko’ was increased to the level measured in ‘Wanad’. This effect was associated with higher microspore culture viability and increased stress tolerance in ‘Mieszko’. Low temperature and metabolic starvation during 4-day anther preculture did not influence activities of antioxidative enzymes, while it resulted in slight decrease in respiration rate and heat emission. The importance of these changes for effective androgenesis induction is discussed.     

Markers associated with a QTL for grain yield in wheat under drought

Drought is a major abiotic stress that adversely affects wheat production in many regions of the world. The objective of this study was to identify quantitative trait loci (QTL) controlling grain yield and yield components under reduced moisture. A cross between common wheat cultivars ‘Dharwar Dry’ (drought tolerant) and ‘Sitta’ was the source of one hundred twenty-seven recombinant inbred lines evaluated for two-seasons in a field under differing soil moisture regimes in Ciudad Obregon, Sonora, Mexico. An SSR/EST-STS marker map was constructed and a grain yield QTL on the proximal region of chromosome 4AL was found to have a significant impact on performance under reduced moisture. This region was associated with QTL for grain yield, grain fill rate, spike density, grains m⁻², biomass production, biomass production rate, and drought susceptibility index (DSI). Molecular markers associated with these traits explained 20, 33, 15, 23, 30, 26, and 41% of phenotypic variation, respectively on chromosome 4A. Microsatellite locus Xwmc89 was associated with all significant QTL covering a 7.7 centiMorgans (cM) region and generally explained the greatest proportion of phenotypic variation. The alleles associated with enhanced performance under drought stress were contributed by Dharwar Dry. Microsatellite marker wmc89 may be useful for marker assisted selection to enhance drought tolerance.     

Restoration of vigor and rooting competence in stem tissues of mature citrus by repeated grafting of their shoot apices onto freshly germinated seedlings in vitro

Summary Repeated grafting of 0.2-cm shoot tips from fruiting-age trees ofCitrus reticulata Blanco ‘Ponkan’ mandarin andC. sinensis Osbeck ‘Liu Tseng’ sweet orange onto freshly germinated ‘Troyer’ citrange [Poncirus trifoliata (L.) Raf. X.C. sinensis Osbeck] seedlings in vitro resulted in progressive restoration of rooting competence and vigor of regenerated roots and shoots. The restored traits were retained through the course of the investigation and suggested a phase reversal phenomenon.