scholarly journals A Serum Amylase Polymorphism in Populations of the Brush-Tailed Possum Trichosurus Vulpecula

1970 ◽  
Vol 23 (1) ◽  
pp. 235 ◽  
Author(s):  
RM Hope ◽  
DJ Finnegan
Keyword(s):  
Gel Electrophoresis ◽  
Experimental Approach ◽  
Serum Amylase ◽  
Natural Populations ◽  
Single Species ◽  
Evolutionary Significance ◽  
Factors Affecting ◽  
Biochemical Polymorphisms ◽  
Amylase Polymorphism ◽  
Biochemical Variation

During the last ten years, the techniques of gel electrophoresis have revealed a large amount of heritable biochemical variation in populations of many organisms. Lewontin and Hubby (1966) have estimated that on the average 30% of all loci are heterozygous in natural populations of Drosophila pseudoobscura, and similar estimates have been obtained for other species of Drosophila (O'Brien and MacIntyre 1969) and for man (Harris 1966). The ecological and evolutionary significance of this variation is as yet almost completely unknown. An experimental approach to this problem is to study the nature and extent of variation within and between samples from subpopulations of a single species, and to relate this variation to environmental factors and breeding structure. This approach has indicated the nature of the selection on several morphological polymorphisms (Sheppard 1959; Kettlewell 1965) but with the exception ofthe sickle cell haemoglobin polymorphism in man (Allison 1954) it has provided little evidence concerning the factors affecting biochemical polymorphisms.

Reynolds-averaged Navier–Stokes simulation of hydrofoil effects on hydrodynamic coefficients of a catamaran in forced oscillation

2016 ◽  
Vol 231 (2) ◽  
pp. 364-383
Author(s):  
Amin Najafi ◽  
Mohammad Saeed Seif
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Navier Stokes ◽  
Hydrodynamic Coefficients ◽  
Laboratory Equipment ◽  
Factors Affecting ◽  
High Frequencies ◽  
Frequency Independent ◽  
Reynolds Averaged Navier Stokes

Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using Reynolds-averaged Navier–Stokes method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly and requires meticulous laboratory equipment; therefore, utilizing the numerical methods and developing a virtual laboratory seem highly efficient. In this study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency-independent especially at high frequencies.

scholarly journals Lactobacillus fructivorans Spoilage of Tomato Ketchup

1997 ◽  
Vol 60 (5) ◽  
pp. 505-509 ◽  
Author(s):  
K. JOHANNA BJORKROTH ◽  
HANNU J. KORKEALA
Keyword(s):  
Gel Electrophoresis ◽  
Microbial Growth ◽  
Antimicrobial Agents ◽  
Growth And Survival ◽  
Factors Affecting ◽  
Physiological And Biochemical Characteristics ◽  
Gas Formation ◽  
Tomato Ketchup ◽  
Dna Fragment ◽  
Physiological And Biochemical

Spoilage characterized by bulging as a result of gas formation in bottled ketchup was studied, Samples produced microbial growth on MRS and Rogosa selective Lactobacillus agar. Seventy randomly selected isolates typed by using restriction endonuclease (ClaI, EcoRI, HindIII) analysis were found to have identical DNA fragment patterns in gel electrophoresis. The strain was identified as Lactobacillus fructivorans using morphological, physiological and biochemical characteristics, combined with the information obtained from ribotyping. Factors affecting growth and survival of this L. fructivorans strain in ketchup production were also studied. An L. fructivorans count of 105 CFU/g resulted in spoilage of inoculated ketchup samples. Spoilage occurred only in samples incubated at 15 to 30°C. The L. fructivorans implicated in causing spoilage demonstrated heat resistance with a D value of 1.2 min at 65°C. The strain did not show resistance to alkaline active chloride-containing detergent sanitizer; alkyldimethylbenzylammonium chloride and alkyldimethylethylbenzylammonium chloride-containing sanitizer were also found to be effective antimicrobial agents.

scholarly journals Nucleotide sequences of highly repeated DNAs; compilation and comments

1982 ◽  
Vol 39 (1) ◽  
pp. 1-30 ◽  
Author(s):  
George L. Gabor Miklos ◽  
Amanda Clare Gill
Keyword(s):  
Satellite Dna ◽  
Germ Line ◽  
Sequence Data ◽  
Allelic Variation ◽  
Neutral Theory ◽  
Natural Populations ◽  
Evolutionary Significance ◽  
Nucleotide Sequence Data ◽  
A Genome ◽  
Repeated Dnas

SummaryThe nucleotide sequence data from highly repeated DNAs of inverte-brates and mammals are summarized and briefly discussed. Very similar conclusions can be drawn from the two data bases. Sequence complexities can vary from 2 bp to at least 359 bp in invertebrates and from 3 bp to at least 2350 bp in mammals. The larger sequences may or may not exhibit a substructure. Significant sequence variation occurs for any given repeated array within a species, but the sources of this heterogeneity have not been systematically partitioned. The types of alterations in a basic repeating unit can involve base changes as well as deletions or additions which can vary from 1 bp to at least 98 bp in length. These changes indicate that sequence per se is unlikely to be under significant biological constraints and may sensibly be examined by analogy to Kimura's neutral theory for allelic variation. It is not possible with the present evidence to discriminate between the roles of neutral and selective mechanisms in the evolution of highly repeated DNA.Tandemly repeated arrays are constantly subjected to cycles of amplification and deletion by mechanisms for which the available data stem largely from ribosomal genes. It is a matter of conjecture whether the solutions to the mechanistic puzzles involved in amplification or rapid redeployment of satellite sequences throughout a genome will necessarily give any insight into biological functions.The lack of significant somatic effects when the satellite DNA content of a genome is significantly perturbed indicates that the hunt for specific functions at the cellular level is unlikely to prove profitable.The presence or in some cases the amount of satellite DNA on a chromosome, however, can have significant effects in the germ line. There the data show that localized condensed chromatin, rich in satellite DNA, can have the effect of rendering adjacent euchromatic regions rec−, or of altering levels of recombination on different chromosomes. No data stemming from natural populations however are yet available to tell us if these effects are of adaptive or evolutionary significance.

scholarly journals Factors affecting the herbage iodine content.

1974 ◽  
Vol 22 (3) ◽  
pp. 195-206 ◽  
Author(s):  
J. Hartmans
Keyword(s):  
Soil Type ◽  
Dry Matter ◽  
Field Experiments ◽  
Iodine Content ◽  
Single Species ◽  
Residual Effects ◽  
Grass Species ◽  
Yield Response ◽  
N Application ◽  
Factors Affecting

In pot and field experiments, N application somewhat increased the I content of the harvested crop, although I concentrations in the herbage decreased considerably (diluting effect of increased dry matter yields). Herbage I contents were not consistently affected by chemical fertilizers which produced no yield response. I contents were up to 13 times higher in dicotyledenous pasture species than in grasses. I contents varied between grass species and to less extent between varieties of a single species. Contrary to earlier New Zealand data, good quality grasses were lower in I content than medium-value and inferior grasses. Small I dressings were less effective than larger amounts in terms of percentage return in the harvested crop; residual effects in later cuts were always small. The effectiveness of I dressings depended on soil type and tended to be lowest on soils of low natural I content. ADDITIONAL ABSTRACT: Studies were with ryegrass in pots and pastures. N dressing increased I uptake by the crop but reduced the I content considerably because of the diluting effect of higher DM yields. Dressing with fertilizers which did increase yield did not affect herbage I content consistently. Dicotyledonous species in pasture had I contents up to 13 times that of grasses. The I content of grasses varied over a 2-fold range but variation was smaller in a given species. Good quality grasses had a lower I content than inferior grasses. Smaller I dressings gave a smaller percentage return in the crop than larger amounts; the efficiency depended on soil type and tended to be less for soils with the lowest natural I content. (Abstract retrieved from CAB Abstracts by CABI’s permission)

How Giraffes Work

2021 ◽  
Author(s):  
Graham Mitchell
Keyword(s):  
Single Species ◽  
Free Living ◽  
Factors Affecting ◽  
Normal Functions ◽  
Private Lives ◽  
Social Biology ◽  
Biochemical Systems ◽  
In The Wild ◽  
Physiological And Biochemical ◽  
Biological Milieu

There are few creatures more beautiful, more aloof, and more fascinating than giraffes. Once they were plentiful and filled African landscapes, but in 2016 they were re-classified from “least concern” to “vulnerable” by the International Union for Conservation of Nature. Their survival in the wild is not assured. Much has been written about their private lives, about their behavior, social biology, and ecology, and their history in art and diplomacy. But so far no book has been written about their private lives, their physiology, and their anatomy and biochemistry—in short, the normal functions of a free-living animal in its natural environment—and it is these aspects of their lives that are the focus of this book. The study of a single species could be concise and relatively simply told. In reality it is not. A species never evolves in isolation from the general biological milieu in which it finds itself. Tectonics, astronomical physics, climate, and purely biological factors affecting food and water resources all shape the path of their evolution and all interact with its morphology, its internal physiological and biochemical systems, and the behavior patterns that regulate its daily life. Giraffes are no exception, as is revealed as the story told here unfolds. How do giraffes work? The answers lie in a story filled not only with the internal workings of a unique creature, but with geography, climate changes of great magnitude, and the labors of extraordinary people who put many pieces of the puzzle together.

On the evolution and population genetics of hybrid-dysgenesis-causing transposable elements in Drosophila

1986 ◽  
Vol 312 (1154) ◽  
pp. 205-215 ◽  
Keyword(s):  
Population Genetics ◽  
Natural Selection ◽  
Transposable Elements ◽  
Transposable Element ◽  
Natural Populations ◽  
Element Composition ◽  
Hybrid Dysgenesis ◽  
Evolutionary Significance ◽  
Genetic Elements ◽  
Transposable Genetic Elements

Much has been learned about transposable genetic elements in Drosophila , but questions still remain, especially concerning their evolutionary significance. Three such questions are considered here, (i) Has the behaviour of transposable elements been most influenced by natural selection at the level of the organism, the population, or the elements themselves? (ii) How did the elements originate in the genome of the species? (iii) Why are laboratory stocks different from natural populations with respect to their transposable element composition? No final answers to these questions are yet available, but by focusing on the two families of hybrid dysgenesis-causing elements, the P and I factors, we can draw some tentative conclusions.

Vertical Plate Gel Electrophoresis for the Differentiation of Meat Species

1972 ◽  
Vol 55 (3) ◽  
pp. 461-463
Author(s):  
R J Coduri ◽  
A G Rand
Keyword(s):  
Gel Electrophoresis ◽  
Muscle Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Meat Products ◽  
Single Species ◽  
Direct Analysis ◽  
Buffer System ◽  
Mixed Species ◽  
Detection And Identification ◽  
Meat Proteins

Abstract Polyacrylamide gel electrophoresis of fresh meat sarcoplasmic proteins by the vertical plat e technique was studied as a method for the detection and identification of pure and mixed species extracts. A single 7% Cyanogum gel containing 1M urea, in conjunction with a tris-chloride, tris-glycine discontinuous buffer system, produced satisfactory resolution of single species and mixed species muscle protein extracts. Eleetrophoretie patterns were obtained by direct analysis of meat proteins extracted with a tris-chloride-10% glucose extraction buffer at pH 6.7. Mixtures of beef and pork and beef and horse were easily identified. The possibility for a d a p t i n g t h e eleetrophoretie procedure to the analysis of cooked meat products and non-meat proteins is discussed.

On the Touchdown-Takeoff Hysteresis Observed at the Head-Disk Interface in Hard Disk Drives

2005 ◽  
Author(s):  
Rohit P. Ambekar ◽  
David B. Bogy
Keyword(s):  
Experimental Approach ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Intermolecular Forces ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Disk Interface

The touchdown-takeoff velocity hysteresis observed in hard disk drives during CSS or L/UL tests is analyzed using an experimental approach. Tests similar to L/UL were conducted for different slider-disk combinations at different humidities. Factors affecting the touchdown and takeoff velocity were identified on the basis of their domain of operation. It is concluded that the intermolecular forces and meniscus forces are contributing factors to hysteresis, which is also influenced by disk topography and slider dynamics.

Genic heterogeneity and genetic monitoring of mouse outbred stocks

1979 ◽  
Vol 13 (2) ◽  
pp. 81-86 ◽  
Author(s):  
A. Groen ◽  
A. J. Lagerwerf
Keyword(s):  
Gel Electrophoresis ◽  
Allelic Variation ◽  
Total Sample ◽  
Starch Gel Electrophoresis ◽  
Genetic Changes ◽  
Biochemical Polymorphisms ◽  
Routine Monitoring ◽  
Monitoring Procedure ◽  
Starch Gel

Summary An outbred stock of Swiss :SE mice has been surveyed for genic heterogeneity at 12 loci, encoding biochemical polymorphisms in mice. Using horizontal starch-gel electrophoresis, 6 loci (Es-1, Es-2, Es-3, Es-5, Trf, Dip-1) revealed no genic heterogeneity within the total sample of 289 male mice examined. The other 6 loci (Mpi-1, Mup-1, Hbb, Gpi-1, Pgm-1, Ldr-1) each showed a 2–allelic variation within each of the 3 stock units (pavilions) involved. A pavilion effect on the observed genotype numbers was found for Pgm-1 and Gpi-1 (P < 0·10). Inadequate genotyping may have occurred at Gpi-1 and Ldr-1, as suggested by a 'week effect' on the observed genotype numbers (P < 0·05). For studying long-term genetic changes within outbred stocks, a routine monitoring procedure using biochemical polymorphisms is recommended.

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