Variation among Extracted Lines of Drosophila Melanogaster in Triacylglycerol and Carbohydrate Storage

Whole larvae and whole adult extracts from 26 second chromosome replacement lines of Drosophila melanogaster were analyzed to determine the amounts of stored triacylglycerols and carbohydrates as well as the activities of 13 enzymes in relevant biochemical pathways. Analysis of covariance revealed significant differences among lines in stored lipids and carbohydrates, as well as in activities of most of the enzymes. Significant broad-sense genetic correlations (among adjusted line means) were detected for a number of enzyme pairs. Multiple regression techniques were applied to assess the extent to which the amounts of stored triacylglycerols and carbohydrates could be predicted from the enzyme activities. Significant regressions were found in both adults and larvae, suggesting that modulation of enzyme activities is reflected in different sizes of storage pools. The population genetic consequences of natural selection acting on a phenotype such as energy storage is considered in light of models of metabolic flux in biochemical pathways.     

Dipeptidase-C inDrosophila melanogaster: Genetic,ontogenetic, and tissue-specific variation

Dip-A, Dip-B, and Dip-C constitute structural genes for three peptidic enzymes in Drosophila melanogaster distinct from the leucine aminopeptidases. Their ontogenetic and tissue distributions of activities suggest the involvement of these enzymes in a general metabolic role, such as the regulation of amino acid and oligopeptide pools to make amino acids available for protein synthesis. Screening of chromosome substitution isogenic lines for DIP-C activity indicated that, like DIP-A and DIP-B, unlinked activity modifiers exist for Dip-C. The developmental profiles of dipeptidase activities are very similar, except in the pupal stage, during which DIP-C activity is markedly low compared to the other two enzymes. Intercorrelations of dipeptidase activities vary ontogenetically, which is consistent with the need for coordinate expression of these enzymes during certain developmental stages. Tissue-specific expression of dipeptidases in larvae and adults are also similar, although the relative levels of DIP-A activity differ from those of DIP-B and DIP-C in certain organs and body parts. Some of the differences among chromosome substitution lines for dipeptidase activities appear to be systemic, while others are developmental stage-specific and tissue-specific. Second- and third-chromosome variants for DIP-C activity differed in their tissue distribution. This is consistent with the presence of temporal and spatial variants in natural populations for other Drosophila enzymes.     

GENETIC COMPONENTS OF VARIATION IN ENERGY STORAGE IN DROSOPHILA MELANOGASTER

One approach to examining the underlying genetic structure of the variation in a continuous phenotype is to measure a set of possibly mechanistically related traits and determine the quantitative genetic aspects of their transmission. In this study the quantities of stored triacylglycerol and glycogen were measured along with the activities of 10 enzymes in related metabolic pathways in a set of 1,157 half-sib families of Drosophila melanogaster. The families were structured with each male being mated to 10 females and two offspring were scored from each female. Parents and offspring were scored for the phenotypes, and the components of variance (additive, dominance, and environmental) were estimated in three ways, including analysis of variance on offspring alone, parent-offspring regression, and maximum likelihood methods. While there were differences among the estimates made by the three methods, a consistent result was that substantial additive genetic variation was detected for all the traits. Consistent with models for the quantitative genetics of enzyme kinetics, the genetic variances of global properties were largely additive. Previous studies with extracted chromosome lines had indicated several significant genetic correlations among these characters, and much of the correlation was attributable to additive effects. The results imply that there is substantial opportunity for natural or artificial selection to act on quantities of stored lipid and carbohydrate, and that the response to selection is likely to be in part mediated by changes in the kinetics of the enzymes targeted in this study.     

Naturally Occurring Enzyme Activity Variation in DROSOPHILA MELANOGASTER. I. Sources of Variation for 23 Enzymes

The genetic component of variation of enzyme activity levels in Drosophila melanogaster was investigated by using 48 second- and 48 third-chromosome isogenic substitution lines derived from natural populations. The results confirm those of our earlier experiments with the same lines and extend them to a number of additional enzymes. All 23 enzymes show a significant genetic component to the variation in one or both sets of lines and only a small part of this variation is accounted for by variation among the lines in the amount of tissue per fly. The magnitude of line effects is, in most cases, considerably larger than the magnitude of environmental and measurement error effects, and the line effects are approximately continuous in distribution. Variation in the geographic origin and karyotype of the chromosomes generally does not contribute to the line component of variation, but allozymes provide an important source of variation for a few of the enzymes. Many of the enzymes show evidence for variation of activity modifiers that are not linked to the structural locus of the enzyme.     

Causes and Consequences of Variation in Energy Storage in Drosophila Melanogaster

Variation in energy storage pools has a proximate cause variation in rates of influx and efflux from the pools, and it may, as an ultimate consequence, result in variation in fitness. The possibility of this chain of causal links motivates attempts to quantify the genetic correlations among pool sizes, enzyme activities and fitness components. In this report, homogenates from 83 second chromosome replacement lines of Drosophila melanogaster were analyzed to determine the amounts of stored triacylglycerols and glycogen as well as the activities of 11 enzymes in relevant metabolic pathways. The viabilities and fecundities of these same lines were determined by a segregation test using the SM5 balancer chromosome. Analysis of covariance revealed significant differences among lines in quantities of stored triacylglycerols and glycogen, as well as in activities of the assayed enzymes. Significant broad-sense genetic correlations were detected for a number of enzyme pairs. Some of the traits showed a significant correlation with viability and fecundity, including lipid and glycogen storage. Multiple regression models that fitted fitness components to linear and quadratic functions of the biochemical traits yielded highly significant fits. The partial regression coefficients indicate the shape of the selection gradient, and instances of significant directional and stabilizing selection were detected.     

An additive-dominance model to determine chromosomal effects in chromosome substitution lines and other gemplasms

When using chromosome substitution (CS) lines in a crop breeding improvement program, one needs to separate the effects of the substituted chromosome from the remaining chromosomes. This cannot be done with the traditional additive-dominance (AD) model where CS lines, recurrent parent, and their hybrids are used. In this study, we develop a new genetic model and software, called a modified AD model with genotype × environment interactions, which can predict additive and dominance genetic effects attributed to a substituted alien chromosome in a CS line as well as the overall genetic effects of the non-substituted chromosomes. In addition, this model will predict the additive and dominance effects of the same chromosome of interest (i.e. chromosome 25 of cotton in this study) in an inbred line, as well as the effects of the remaining chromosomes in the inbred line. The model requires a CS line, its recurrent parent and their F₁ and/or F₂ hybrids between the substitution lines and several inbred lines. Monte Carlo simulation results showed that genetic variance components were estimated with no or slight bias when we considered this modified AD model as random. The correlation coefficient between predicted effects and true effects due to the chromosomes of interest varied from zero to greater than 0.90 and it was positively relative to the difference between the CS line and the recurrent line. To illustrate the use of this new genetic model, an upland cotton, Gossypium hirsusum L, CS line (CS-B25), TM-1 (the recurrent parent), five elite cultivars, and the F₂ hybrids from test-crossing these two lines with the five elite cultivars were grown in two environments in Mississippi. Agronomic and fiber data were collected and analyzed. The results showed that the CS line, CS-B25, which has chromosome 25 from line 3 to 79, Gossypium barbadense substituted into TM-1, had positive genetic associations with several fiber traits. We also determined that Chromosome 25 from FiberMax 966 had significantly positive associations with fiber length and strength; whereas, chromosome 25 from TM-1 and SureGrow 747 had detectable negative genetic effects on fiber strength. The new model will be useful to determine effects of the chromosomes of interest in various inbred lines in any diploid or amphidiploid crop for which CS lines are available.     

Micro-spatial population differentiation in activity of glycerol-3-phosphate oxidase (GPO) from mitochondria of Drosophila melanogaster

Replicate mass-bred laboratory populations of D. melanogaster were derived from females collected in the Tahbilk winery cellar and from females collected outside but from within two kilometres of the cellar. When mitochondrial extracts from larvae were assayed for specific activity of glycerol-3-phosphate oxidase the cellar populations had levels only 50% of those from the outside area, confirming an earlier report of such a difference among isofemale lines derived from these same areas. This micro-spatial differentiation occurred when larvae were raised on a medium supplemented with both sucrose (5% w/v) and ethanol (4% v/v), known to effect high GPO activity, but was not detected when the larvae were raised on unsupplemented medium.A heritable basis for larval GPO activity variation was confirmed in a set of 32 isogenic second chromosome substitution lines and measured in a subset of 4 of these lines about 25 generations later. A reciprocal cross using two isogenic substitution lines with the highest and lowest activities suggested the difference was attributable to genes acting additively and that there were no maternal or paternal effects. The detection of a collection site difference in GPO enzyme activity in the isogenic lines suggests that polymorphic variation on the second chromosome is responsible for the differentiation at the winery.Variation in adult GPO activity did not show a dependence on the winery location from where the isogenic lines were derived nor was there an effect of line. Adult GPO activity was significantly higher than that detected in larval tissues and did not show a dependence on the sugar/ethanol level in the growth medium.     

Monosomic and double monosomic substitutions of Hordeum bulbosum L. chromosomes into H. vulgare L.

Summary One of the aims of the interspecific crossing programme between Hordeum vulgare L. and H. bulbosum L. has been to introgress desirable genes into barley from the wild species. However, despite their close taxonomic relationship there have been few reports of achieving this objective using amphidiploid hybrids. In order to broaden the range of available hybrids, partially fertile triploids between H. vulgare (2n = 2x = 14) and H. bulbosum (2n = 4x = 28) were developed and crossed with H. vulgare as female parent. From 580 progeny which were screened, eight putative single monosomic chromosome substitution lines and one double monosomic substitution were identified by cytological analysis. These involved the substitution of H. vulgare chromosome 1 (two lines), 6 (four lines), 6L (one line), 7 (one line) and 1 + 4 (one line) by their respective H. bulbosum homoeologues. The H. bulbosum chromosome was frequently eliminated during plant development, but it was observed regularly in pollen mother cells of two lines. However, pairing between the H. bulbosum chromosome and its H. vulgare homoeologue was low. Several of the lines were more resistant than their H. vulgare parents to powdery mildew (Erysiphe graminis DC. f.sp. hordei Em. Marchai), net blotch (Drechslera teres Sacc.) and scald (Rhynchosporium secalis (Oudem.) Davis). Apart from their use in studying genome relationships, their value to plant breeders will depend on the ease of inducing translocations between the parental chromosomes.     

Genetic Variability of Flight Metabolism in DROSOPHILA MELANOGASTER . II. Relationship between Power Output and Enzyme Activity Levels

The major goal of the studies reported here was to determine the extent to which genetic variation in the activities of the enzymes participating in flight metabolism contributes to variation in the mechanical power output of the flight muscles in Drosophila melanogaster. Isogenic chromosome substitution lines were used to partition the variance of both types of quantitative trait into genetic and environmental components. The mechanical power output was estimated from the wingbeat frequency, wing amplitude and wing morphology of tethered flies by applying the aerodynamic models of Weis-Fogh and Ellington. There were three major results. (1) Chromosomes sampled from natural populations provide a large and repeatable genetic component to the variation in the activities of most of the 15 flight metabolism enzymes investigated and to the variation in the mechanical power output of the flight muscles. (2) The mechanical power output is a sensitive indicator of the rate of flight metabolism (i.e., rate of oxygen consumption during tethered flight). (3) In spite of (1) and (2), no convincing cases of individual enzyme effects on power output were detected, although the number and sign of the significant enzyme-power correlations suggests that such effects are not totally lacking.     

应用基因组原位杂交及RFLP标记鉴定小麦中的大麦染色体

用生物素（Biotin-6-dUTP)标记的大麦Betzes基因组DNA作探针,以普通小麦中国春总DNA作封阻进行基因组原位杂交（Genomeinsituhybridization,简称GISH）,从13株小麦-大麦杂交后代中鉴定出2个含有3条大麦Betzes2H染色体的材料（2n＝43）;2个2H单体异代换系（2n＝42）;7个2H二体异代换系（2n＝42）。用已定位在小麦第2部分同源群短臂上的探针psr131进行RFLP分析,结果表明大麦Betzes、代换系A5有1条区别于小麦中国春的特异带,A     

Autosomal Factors with Correlated Effects on the Activities of the Glucose 6-Phosphate and 6-Phosphogluconate Dehydrogenases in DROSOPHILA MELANOGASTER

Isogenic lines, in which chromosomes sampled from natural populations of D. melanogaster are substituted into a common genetic background, were used to detect and partially characterize autosomal factors that affect the activities of the two pentose phosphate pathway enzymes, glucose 6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). The chromosome 3 effects on G6PD and 6PGD are clearly correlated; the chromosome 2 effects, which are not so great, also appear to be correlated, but the evidence in this case is not so strong. Examination of activity variation of ten other enzymes revealed that G6PD and 6PGD are not the only pair of enzymes showing a high positive correlation, but it is among the highest in both sets of lines. In addition, there was some evidence that the factor(s) affecting G6PD and 6PGD may also affect two other metabolically related enzymes, transaldolase and phosphoglucose isomerase.—Rocket immunoelectrophoresis was used to estimate specific CRM levels for three of the enzymes studied: G6PD, 6PGD and ME. This experiment shows that a large part of the activity variation is accounted for by variation in CRM level (especially for chromosome 3 lines), but there remains a significant fraction of the genetic component of activity variation that is not explained by CRM level.—These results suggest that the autosomal factors are modifiers involved in regulation of the expression of the X-linked structural genes for G6PD and 6PGD, but a role in determining part of the enzymes' primary structure cannot be excluded with the present evidence.     

Introgression of wheat chromosome 2D or 5D into tritordeum leads to free-threshing habit.

Hexaploid tritordeum is the amphiploid derived from the cross between the diploid wild barley Hordeum chilense and durum wheat. The non-free-threshing habit is a constraint to this species becoming a new crop. Three tritordeum lines (HT374, HT376, and HT382) showing the free-threshing habit were selected from crosses between tritordeum and bread wheat. All three lines were euploids, as revealed by mitotic chromosome counting. Genomic in situ hybridization analysis made it possible to distinguish differences among these lines. While the line HT382 carries only 10 chromosomes from H. chilense, the lines HT374 and HT376 have 12. These results suggest that HT382 is a double chromosome substitution line between H. chilense and the wheat D genome, while HT374 and HT376 each have one pair of H. chilense (Hch) chromosomes substituted by wheat D chromosomes. Molecular characterization revealed that HT382 is a 1D/(1Hch), 2D/(2Hch) chromosome substitution line, whereas HT374 and HT376 have 5D/(5Hch) substitutions. On the basis of previous knowledge, it seems that the absence of chromosome 2Hch or 5Hch is more important for producing the free-threshing habit than the presence of chromosome 2D or 5D, while chromosome 1Hch seems to be unrelated to the trait. These free-threshing tritordeum lines constitute an important advance in the tritordeum breeding program.     

Negative correlations between resistance to three organophosphate insecticides and productivity within a natural population of Drosophila melanogaster (Diptera: Drosophilidae)

To investigate the relationship between resistance to organophosphate insecticides and fitness components, we first measured resistance to three organophosphates, malathion, prothiophos, and fenitrothion, and productivity, a measure of fitness components, for each of the isofemale lines from the same natural population of Drosophila melanogaster (Meigen). Pearson correlation coefficients indicated that positive correlations among resistance to the organophosphates and negative correlations between resistance to each of the organophosphates and the productivity existed within the natural population. We further investigated the genetic basis of the correlations among resistance to the organophosphates and the productivity, by using chromosome-substituted lines between a resistant and a susceptible inbred line established from the same natural population. Chromosomal analyses indicated that the third chromosome from the resistant line exhibited not only significant, positive effects on resistance to all of the organophosphates tested but also a significant negative effect on the productivity, suggesting positive genetic correlations between resistance to each organophosphate and negative genetic correlations between resistance to each organophosphate and the productivity. In addition, a significant negative effect on the productivity was also detected from the second chromosome, which did not exhibit significant major effects on resistance to the organophosphates. This suggests that fitness components of resistant lines could be also affected by factors independent of insecticide resistance. The dynamics of genetic variation in resistance to the organophosphates within the natural population of D. melanogaster are discussed from the standpoint of negative genetic correlations between resistance to the organophosphates and the productivity.     

Morphometrische Studien anValeriana officinalis s. l. Auswahl,Analyse und Aufbereitung der Merkmale

Valeriana officinalis s. l. is an extremely polymorphic polyploid complex. A multivariate morphometric study is the only adequate method to cope with the diversity largely based on quantitative differences. 50 morphological characters have been carefully chosen with regard to their expected taxonomic relevance. The use of program packages for (multivariate) statistical and taxometric evaluation of the data has been made possible by the development of a series of computer programs. They allow different manipulations of the data as well as the extraction of distance or similarity matrices from mixed-type data (i.e. data containing quantitative as well as binary characters). In addition, a computer-based study of the relationships between variables has been carried out by a grouping of variables into subsets according to their B-coefficients (being defined as the ratio of the average of the intercorrelations among the variables of a group to their average correlations with the remaining variables). This technique can also be applied in cases where parts of the material show extremely different correlation patterns, as inValeriana officinalis s. l.     

The effect of the 4B chromosomes of hexaploid wheat on the growth and regeneration of callus cultures

Summary Calli were initiated from immature embryos of nine lines of hexaploid wheat (Triticum aestivum L. em. Thell). These were the euploid lines Chinese Spring and Cappelle-Desprez, a line of Chinese Spring ditelocentric for the long arm of 4B, four substitution lines of Chinese Spring in which chromosome 4B has been replaced by its homologues from different wheat varieties and substituted into Chinese Spring and a substitution line of Besostaya I 4B into Cappelle-Desprez. The calli from these lines were found to differ in their growth rates and morphogenic and regenerative activities. The substitution of different 4B chromosomes into Chinese Spring significantly increased morphogenesis and shoot regeneration from callus. The potential for developing wheat lines with improved culture characteristics is discussed.     

Delineation of interspecific epistasis on fiber quality traits in Gossypium hirsutum by ADAA analysis of intermated G. barbadense chromosome substitution lines

Genetic diversity is the foundation of any crop improvement program, but the most cultivated Upland cotton [Gossypium hirsutum L., 2n?=?52, genomic formula?2(AD)₁] has a very narrow gene pool resulting from its evolutionary origin and domestication history. Cultivars of this cotton species (G. hirsutum L.) are prized for their combination of exceptional yield, other agronomic traits, and good fiber properties, whereas the other cultivated 52-chromosome species, G. barbadense L. [2n?=?52, genomic formula?2(AD)₂], is widely regarded as having the opposite attributes. It has exceptionally good fiber qualities, but generally lower yield and less desirable agronomic traits. Breeders have long aspired to combine the best attributes of G. hirsutum and G. barbadense, but have had limited success. F₁ hybrids are readily created and largely fertile, so the limited success may be due to cryptic biological and technical challenges associated with the conventional methods of interspecific introgression. We have developed a complementary alternative approach for introgression based on chromosome substitution line, followed by increasingly sophisticated genetic analyses of chromosome-derived families to describe the inheritance and breeding values of the chromosome substitution lines. Here, we analyze fiber quality traits of progeny families from a partial diallel crossing scheme among selected chromosome substitution lines (CS-B lines). The results provide a more detailed and precise QTL dissection of fiber traits, and an opportunity to examine allelic interaction effects between two substituted chromosomes versus one substituted chromosome. This approach creates new germplasm based on pair wise combinations of quasi-isogenic chromosome substitutions. The relative genetic simplicity of two-chromosome interactions departs significantly from complex or RIL-based populations, in which huge numbers of loci are segregating in all 26 chromosome pairs. Data were analyzed according to the ADAA genetic model, which revealed significant additive, dominance, and additive-by-additive epistasis effects on all of the fiber quality traits associated with the substituted chromosome or chromosome arm of CS-B lines. Fiber of line 3-79, the donor parent for the substituted chromosomes, had the highest Upper Half Mean length (UHM), uniformity ratio, strength, elongation, and lowest micronaire among all parents and hybrids. CS-B16 and CS-B25 had significant additive effects for all fiber traits. Assuming a uniform genetic background of the CS-B lines, the comparative analysis of the double-heterozygous hybrid combinations (CS-B?×?CS-B) versus their respective single heterozygous combinations (CS-B?×?TM-1) demonstrated that interspecific epistatic effects between the genes in the chromosomes played a major role in most of the fiber quality traits. Results showed that fiber of several hybrids including CS-B16?×?CS-B22Lo, CS-B16?×?CS-B25 and CS-B16?×?TM-1 had significantly greater dominance effects for elongation and hybrid CS-B16?×?CS-B17 had higher fiber strength than their parental lines. Multiple antagonistic genetic effects were also present for fiber quality traits associated with most of the substituted chromosomes and chromosome arms. Results from this study highlight the vital importance of epistasis in fiber quality traits and detected novel effects of some cryptic beneficial alleles affecting fiber quality on the 3-79 chromosomes, whose effects were not detected in the 3-79 parental lines.     

Incorporation rate of glucose carbon, palmitate carbon and leucine carbon into metabolites in relation to enzyme activities and RNA levels in human skeletal muscles.

The activities (Vmax) of hexokinase, glycogen phosphorylase, glucose-6-phosphate dehydrogenase, phosphofructokinase, lactate dehydrogenase, citrate synthase, cytochrome c oxidase, and 3-OH-acyl-CoA dehydrogenase in human skeletal muscles were compared with the in vitro utilization of glucose and palmitic acid assessed under optimal conditions. Statistically significant correlations between substrate fluxes and enzyme activities were found suggesting that the substrate incorporation rate in vitro in some way reflects the capacity of metabolic pathways. The incorporation rate of leucine into muscle proteins was also statistically significantly correlated to the RNA concentration in the muscle tissue. Glycolytic and glycogenolytic enzymes correlated significantly to each other and correlations were also found between aerobic enzymes supporting the validity of constant proportions between certain key enzymes in human skeletal muscles.     

小麦新种质4844中外源P染色质的GISH与SSR分析

采用基因组原位杂交(GISH)检测和染色体组成分析方法,对大穗多花小麦新种质4844后代的15个株系进行遗传分析。结果发现,4844-12是1个稳定的异附加系,4844-2和4844-8是稳定的异代换系;对异代换系进行SSR分析表明,代换系中小麦的6D染色体被1对P染色体代换,说明这对冰草染色体与小麦6D染色体有部分同源关系,由此确定4844中的冰草染色体为6P;同时筛选出冰草6P染色体的4个SSR标记。