Novel quantitative phenotypes of exercise training in mouse models

Regular physical exercise has beneficial effects in many human disease states, including cardiovascular diseases, cancer, and depression. Exercise training of genetically modified mouse models may provide insight into the molecular mechanisms that underlie the beneficial effects of exercise. Presently, there is relatively little understanding of the normal physiology of mouse exercise. In this paper, we describe a novel computerized voluntary wheel-running system capable of recording and analyzing individual wheel rotations. Using this system, we demonstrate that C57BL/6 mice run considerable distances during the night in short bouts and at a preferred speed: the cruising speed. We find that the vast majority of running occurs around this cruising speed, which is close to the maximum speed at which the animal can run but is significantly higher than the average speeds recorded by simple digital odometers. We describe how these parameters vary with exercise training and demonstrate marked sex differences in the patterns of voluntary exercise. The results of this study have important implications for the design and interpretation of both voluntary and forced exercise experiments in mouse models. The novel parameters described provide more physiological quantitative measures of voluntary exercise activity and training and will extend the physiological utility of exercise training as a phenotyping tool in genetic mouse models.     

Fluorescent image cytometry: from qualitative to quantitative measurements

Image analysis is being increasingly used in biology and medicine; however, in order to obtain truly quantitative data and thus avoid errors in interpretation, a certain number of precautions must be taken when the image is digitized, well before any attempt is made to analyse or interpret the data. This is particularly true for image microfluorometry. In this article we will examine an image analysis system for fluorescent images composed of a mercury lamp, a microscope, a high sensitivity video camera and an image analyser and evaluate the principal sources of random and non-random errors, various constraints, and their relative importance. A signal correction protocol is proposed to minimize non-random errors during digitalization. A few examples are given to illustrate its efficiency.     

AP-1 controls the trafficking of Notch and Sanpodo toward E-cadherin junctions in sensory organ precursors

In Drosophila melanogaster, external sensory organs develop from a single sensory organ precursor (SOP). The SOP divides asymmetrically to generate daughter cells, whose fates are governed by differential Notch activation. Here we show that the clathrin adaptor AP-1 complex, localized at the trans Golgi network and in recycling endosomes, acts as a negative regulator of Notch signaling. Inactivation of AP-1 causes ligand-dependent activation of Notch, leading to a fate transformation within sensory organs. Loss of AP-1 affects neither cell polarity nor the unequal segregation of the cell fate determinants Numb and Neuralized. Instead, it causes apical accumulation of the Notch activator Sanpodo and stabilization of both Sanpodo and Notch at the interface between SOP daughter cells, where DE-cadherin is localized. Endocytosis-recycling assays reveal that AP-1 acts in recycling endosomes to prevent internalized Spdo from recycling toward adherens junctions. Because AP-1 does not prevent endocytosis and recycling of the Notch ligand Delta, our data indicate that the DE-cadherin junctional domain may act as a launching pad through which endocytosed Notch ligand is trafficked for signaling.     

梨小食心虫幼虫寄主选择性和主要感器

[目的]明确梨小食心虫Grapholitha molesta(Busck)幼虫的寄主选择能力和主要感器.[方法]在室内条件下,测定梨小食心虫幼虫在7种寄主果实、不同发育阶段果实及受损伤果实的上的数量,并测定3种感器单独、两两组合处理及3种感器全部处理后的幼虫在不同寄主果实上的数量.[结果]1龄时,选择丰白毛桃、红富士苹...     

Establishing character correspondence for sensory organ traits in flies: sensory organ development provides insight for reconstructing character evolution

In Diptera and in other insects sensory organ patterns play an important role in the construction of phylogenies based on morphological characters. In this paper I explore the developmental basis for sensory organ pattern transformations between and within species. Knowledge of the properties of sensory organ development provides a foundation to judge the correspondence relationships between sensory organs. This is used to explore what components of notum bristle patterns are equivalent across the Schizophora. By investigating patterning processes in leg development, and their conservation across holometabolous insects, I show ways of relating specialised leg vestiture between species. Sensory organ patterns on the legs are diversified under homeotic gene control, potentially adding patterns of homeotic variation between legs to the list of informative traits for phylogenetic analysis. Correspondence relationships between wing and haltere sensory organ fields are resolved by exploring homeotic gene action in detail.     

Diabetic embryopathy and fuel-mediated organ teratogenesis: lessons from animal models

The growing recognition that faulty maternal metabolism during early organogenesis may be implicated in the increased incidence of birth defects in pregnancies complicated by diabetes has prompted worldwide efforts to institute improved preconceptional metabolic regulation. However, the failure to identify the periods of greatest risk for diabetic embryopathy, the mediating teratogen(s), and the underlying mechanisms have complicated attempts to establish precise therapeutic guidelines and targets. Some of the reported in vivo and in vitro experiences with rodent models have been reviewed to derive relevant insights. Substantial literature indicates that diabetes (experimental as well as spontaneous) in pregnant rats and mice is attended by retardation of growth and developmental delay during embryogenesis, and a variable incidence of birth defects. Poor metabolic regulation of the diabetic mother during early organogenesis may also be followed by subsequent resorption of the conceptus at the site of implantation. Vulnerability to diabetes-related resorptions and all other forms of embryopathy appears to begin during the early postimplantation period and is greatest near the onset of neurolation. Overall susceptibility is markedly influenced by genetic factors and may be modified by the antecedent metabolic exposures of the conceptus ("carry-over effects"). Mediation for the anomalous embryo development in pregnancies of diabetic rodents appears to be multifactorial; all the aberrant fuels and fuel-related components of "the diabetic state" (e.g. high glucose; ketones; somatomedin inhibitor(s); osmolality, etc.) which have been tested to date display dysmorphogenic potential ("fuel-mediated organ terato-genesis") in vitro. All tissues in the conceptus appear to be at risk. Dose-response relationships for the individual metabolic teratogens may be influenced by additive and synergistic interactions so that the integrated possibilities cannot be assessed fully by measurements confined to a single fuel or fuel-related component. In the context of the day-to-day variability in diabetes "control" of the poorly regulated mother, and the relatively longer duration of organogenesis, these multifactorial possibilities may account for the multiple birth defects that can occur in individual offspring, and the seemingly non-specific pattern of diabetic embryopathy. Insulin therapy diminishes the dysmorphogenic effects of "the diabetic state" in rodents with experimental or spontaneous diabetes.(ABSTRACT TRUNCATED AT 400 WORDS)     

A dual function of phyllopod in Drosophila external sensory organ development: cell fate specification of sensory organ precursor and its progeny

During Drosophila external sensory organ development, one sensory organ precursor (SOP) arises from a proneural cluster, and undergoes asymmetrical cell divisions to produce an external sensory (es) organ made up of different types of daughter cells. We show that phyllopod (phyl), previously identified to be essential for R7 photoreceptor differentiation, is required in two stages of es organ development: the formation of SOP cells and cell fate specification of SOP progeny. Loss-of-function mutations in phyl result in failure of SOP formation, which leads to missing bristles in adult flies. At a later stage of es organ development, phyl mutations cause the first cell division of the SOP lineage to generate two identical daughters, leading to the fate transformation of neurons and sheath cells to hair cells and socket cells. Conversely, misexpression of phyl promotes ectopic SOP formation, and causes opposite fate transformation in SOP daughter cells. Thus, phyl functions as a genetic switch in specifying the fate of the SOP cells and their progeny. We further show that seven in absentia (sina), another gene required for R7 cell fate differentiation, is also involved in es organ development. Genetic interactions among phyl, sina and tramtrack (ttk) suggest that phyl and sina function in bristle development by antagonizing ttk activity, and ttk acts downstream of phyl. It has been shown previously that Notch (N) mutations induce formation of supernumerary SOP cells, and transformation from hair and socket cells to neurons. We further demonstrate that phyl acts epistatically to N. phyl is expressed specifically in SOP cells and other neural precursors, and its mRNA level is negatively regulated by N signaling. Thus, these analyses demonstrate that phyl acts downstream of N signaling in controlling cell fates in es organ development.     

Inter-mitochondrial complementation: Mitochondria-specific system preventing mice from expression of disease phenotypes by mutant mtDNA

Here we investigated the pathogenesis of deletion mutant mitochondrial (mt)DNA by generating mice with mutant mtDNA carrying a 4696-basepair deletion (DeltamtDNA4696), and by using cytochrome c oxidase (COX) electron micrographs to identify COX activity at the individual mitochondrial level. All mitochondria in tissues with DeltamtDNA4696 showed normal COX activity until DeltamtDNA4696 accumulated predominantly; this prevented mice from expressing disease phenotypes. Moreover, we did not observe coexistence of COX-positive and -negative mitochondria within single cells. These results indicate the occurrence of inter-mitochondrial complementation through exchange of genetic contents between exogenously introduced mitochondria with DeltamtDNA4696 and host mitochondria with normal mtDNA. This complementation shows a mitochondria-specific mechanism for avoiding expression of deletion-mutant mtDNA, and opens the possibility of a gene therapy in which mitochondria possessing full-length DNA are introduced.     

Hydrolysis of sucrose octa-acetate: qualitative differences in taster and demistaster avoidance phenotypes

Calcium hydroxide and sodium hydroxide were used to hydrolysesucrose octa-acetate (SOA) as a means of evaluating the taster(Soa^a) and demitaster (Soa^c) allelic phenotypes of the geneticlocus Soa. The SWR/J (taster) inbred strain and the B6.SW Soa^a(taster) congenic strain were demonstrated to cease avoidingupon nearly complete hydrolysis of 10^–5 M SOA with calciumhydroxide Or sodium hydroxide and of 10^–4 M SOA with calciumhydroxide. The BALB/cByJ, C3HeB/FeJ and DBA/2J (demitaster)inbred strains were demonstrated to cease avoiding after onlya partial hydrolysis of 10^–3 M SOA using calcium hydroxide.It is suggested that specificity for the number or placementof the acetates of SOA underlies the difference between thetaster and demitaster phenotypes.     

The psychological consequences of weight change trajectories: Evidence from quantitative and qualitative data

We use quantitative and qualitative data to explore the psychological impact of weight change among American adults. Using data from the Midlife Development in the United States (MIDUS) study, a survey of more than 3000 adults ages 25–74 in 1995, we contrast underweight, normal weight, overweight, obese I, and obese II/III persons along five psychosocial outcomes: positive mood, negative mood, perceived interpersonal discrimination, self-acceptance, and self-satisfaction. We further assess whether these relationships are contingent upon one's body mass index (BMI) at age 21. We find a strong inverse association between adult BMI and each of the five outcomes, reflecting the stigma associated with high body weight. However, overweight adults who were also overweight at age 21 are more likely than persons who were previously slender to say they were “very satisfied” with themselves. Results from 40 in-depth semi-structured interviews reveal similarly that persons who were persistently overweight or obese accept their weight as part of their identity, whereas those who experienced substantial weight increases (or decreases) struggle between two identities: the weight they actually are, and the weight that they believe exemplifies who they are. We discuss implications for stigma theory, and the ways that stigma exits and entries affect psychological well-being.     

Quantitative target display: a method to screen yeast mutants conferring quantitative phenotypes by ‘mutant DNA fingerprints’

Whole genome sequencing of several microbes has revealed thousands of genes of unknown function. A large proportion of these genes seem to confer subtle quantitative phenotypes or phenotypes that do not have a plate screen. We report a novel method to monitor such phenotypes, where the fitness of mutants is assessed in mixed cultures under competitive growth conditions, and the abundance of any individual mutant in the pool is followed by means of its unique feature, namely the mutation itself. A mixed population of yeast mutants, obtained through transposon mutagenesis, was subjected to selection. The DNA regions (targets) flanking the transposon, until nearby restriction sites, are then quantitatively amplified by means of a ligation-mediated PCR method, using transposon-specific and adapter-specific primers. The amplified PCR products correspond to mutated regions of the genome and serve as ‘mutant DNA fingerprints’ that can be displayed on a sequencing gel. The relative intensity of the amplified DNA fragments before and after selection match with the relative abundance of corresponding mutants, thereby revealing the fate of the mutants during selection. Using this method we demonstrate that UBI4, YDJ1 and HSP26 are essential for stress tolerance of yeast during ethanol production. We anticipate that this method will be useful for functional analysis of genes of any microbe amenable to insertional mutagenesis.     

Stearoyl-ACP and oleoyl-PC desaturase genes cosegregate with quantitative trait loci underlying high stearic and high oleic acid mutant phenotypes in sunflower

The genetic control of the synthesis of stearic acid (C18:0) and oleic acid (C18:1) in the seed oil of sunflower was studied through candidate-gene and QTL analysis. Two F₂ mapping populations were developed using the high C18:0 mutant CAS-3 crossed to either HA-89 (standard, high linoleic fatty acid profile), or HAOL-9 (high C18:1 version of HA-89). A stearoyl-ACP desaturase locus (SAD17A), and an oleoyl-PC de-saturase locus (OLD7) were found to cosegregate with the previously described Es1 and Ol genes controlling the high C18:0 and the high C18:1 traits, respectively. Using linkage maps constructed from AFLP and RFLP markers, these loci mapped to LG1 (SAD17A) and to LG14 (OLD7) and were found to underlie the major QTLs affecting the concentrations of C18:0 and C18:1, explaining around 80% and 56% of the phenotypic variance of these fatty acids, respectively. These QTLs pleiotropically affected the levels of other primary fatty acids in the seed storage lipids. A minor QTL affecting both C18:0 and C18:1 levels was identified on LG8 in the HAOL-9×CAS-3 F₂. This QTL showed a significant epistatic interaction for C18:1 with the QTL at the OLD7 locus, and was hypothesized to be a modifier of Ol. Two additional minor C18:0 QTLs were also detected on LG7 and LG3 in the HA-89×CAS-3 and the HAOL-9×CAS-3 F₂ populations, respectively. No association between a mapped FatB thioesterase locus and fatty acid concentration was found. These results provide strong support about the role of fatty acid desaturase genes in determining fatty acid composition in the seed oil of sunflower. Received: 7 December 2000 / Accepted: 21 May 2001     

A dnaT mutant with phenotypes similar to those of a priA2::kan mutant in Escherichia coli K-12

The ability to repair damaged replication forks and restart them is important for cell survival. DnaT is essential for replication restart in vitro and yet no definite genetic analysis has been done in Escherichia coli K-12. To begin, dnaT822, an in-frame six-codon (87-92) deletion was constructed. DnaT822 mutants show colony size, cell morphology, inability to properly partition nucleoids, UV sensitivity, and basal SOS expression similar to priA2::kan mutants. DnaT822 priA2::kan double mutants had phenotypes similar to those of the single mutants. DnaT822 and dnaT822 priA2::kan mutant phenotypes were fully suppressed by dnaC809. Previously, a dominant temperature-sensitive lethal mutation, dnaT1, had been isolated in E. coli 15T(-). DnaT1 was found to have a base-pair change relative to the E. coli 15T(-) and E. coli K-12 dnaT genes that led to a single amino acid change: R152C. A plasmid-encoded E. coli K-12 mutant dnaT gene with the R152C amino acid substitution did not display a dominant temperature-sensitive lethal phenotype in a dnaT(+) strain of E. coli K-12. Instead, this mutant dnaT gene was found to complement the E. coli K-12 dnaT822 mutant phenotypes. The significance of these results is discussed in terms of models for replication restart.