bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetical and Cytological Studies of Lethals induced by Chemical Treatment inDrosophila melanogaster.
Authors: Slizynska Helen , Slizynski B. M. 
Published: June 2019

Thepresent paper forms a continuation of studies of recessive sex-linked lethals inDrosophila melanogasterpublished previously (1938, 1941). In these, lethals occurring spontaneously, induced by X-ray treatment and by ultra-violet light were examined cytologically in the salivary gland chromosomes.The genetic factors which stop or change the development of an individual in such a way that its death ensues under normal conditions are termed lethals. A lethal effect may be connected with a mutation of a gene or with its absence from the chromosome: those which cannot be proved to be associated with the absence of a cytologically detectable part of the chromosome are considered as due to “point” mutations.The absence of a microscopically identifiable section of a chromosome with all its genetical and structural elements is called a deficiency. With few exceptions (Muller, 1935; Demerec and Hoover, 1936) the deficiencies in the X-chromosome, whatever their size and whatever loci they involve, are lethal for males. In females heterozygous for them deficiencies of small or even moderate size usually do not produce any visible phenotypical effect, although some cases are known (Mohr, 1923; Slizynska, 1938) in which a heterozygous deficiency for a particular band is always associated with a definite phenotype. Thus a lethal effect may or may not be the result of a deficiency, while a deficiency in the X-chromosome almost always has a lethal effect in the males.In 1941 Auerbach (1943, 1946 in press) succeeded in producing “visible” and lethal mutations and chromosomal rearrangements by chemical treatment in which adult males were exposed to vapours of (C1CH2CH2)2S in a specially designed apparatus. The object of this paper is to show what proportion of sex-linked recessive lethals produced inDrosophila melanogasterby these new agents is connected with detectable deficiencies. Besides finding out whether chemically produced lethals are associated with detectable deficiencies, the problem of the relation between lethals and “visible” mutations is discussed on the basis of their respective distributions along the chromosome. It should be stated that the lethals connected with gross structural changes represent probably only a small fraction of such lethals actually produced since many of them were eliminated by zygotic lethality.
Tests of Chemical Substances for Mutagenic Action
Authors: Auerbach C. , Robson J. M. 
Published: June 2019

Thediscovery in 1941 (Auerbach and Robson, first published in 1946) that mustard gas (β-β′-dichloro-diethyl-sulphide), (ClCH2.CH2)2S, is comparable to X-rays in its capacity to produce mutations and chromosome rearrangements naturally raised the question as to what special properties of mustard gas enable it to act in this manner. There are indications (Auerbach and Robson, 1947) that the mutagenic effects of mustard gas are due to a direct action on the chromosomes, and not to an indirect oneviathe cytoplasm. This suggests that a selective and specific chemical reaction occurs between mustard gas and the genie material. It appeared possible that a systematic survey of substances chemically related to mustard gas might reveal a chemical group or structural arrangement responsible for the mutagenic action. This in its turn might also throw some light on the other component of the reaction, the gene or chromosome, and on the process of mutation itself.The substances, to be tested were, with one exception, chosen on account of their chemical and pharmacological similarity to mustard gas. They were:(1) N-methyl di-(2-chloroethyl) amine, CH3.N(CH2.CH2Cl)2, one of the so-called nitrogen mustards. This is a liquid with strong vesicant action. It decomposes fairly rapidly in water. Its hydrochloride is a solid, soluble in water and forming a stable solution. This solution proved useful in certain tests in which it was convenient to apply a mutagenic substance in aqueous solution.
A Comparative Study of the Chromosome Structure and Behaviour in Three Different Genera of Indian Grasshoppers
Authors: Ray-Chaudhuri S. R. , Dutt M. K. , Greenwood A. W. 
Published: June 2019

The Acrididæ are characterised by a very uniform karyotype. With a few exceptions, the species so far studied contain 23 chromosomes in the male, which are very similar in size and structure. Attempts to deduce the probable mechanism of speciation within the Acrididæ were restricted only to metrical studies of chromosomes. Recently, however, Coleman (1943) has established in two species the subterminal position of the primary constriction or centromere and the variation in the length of the two arms in different chromosomes of the same karyotype. In the present paper additional evidence is presented which shows a linear differentiation of some chromosomes of the Acrididæ. Furthermore, in view of the fact that chromosome behaviour during meiosis is a more reliable criterion of ascertaining linear differentiation, the meiosis was studied in three genera.Three species belonging to three different genera were studied. They are Spathosternum prasiniferum Walker, Oxya sp. and Phlœoba sp. The former two belong to the sub-family Catantopinæ and the latter one to Acrididæ. Adult male specimens have been captured from the field adjoining the Biological Departments, Calcutta University, mostly in the months of August and September 1943–44. The testes were dissected out in Ringer's solution (cold-blooded formula) and fixed in Medium Flemming, Belling's, and Kahle's fixatives. The two latter were very suitable for smear preparations. Sections were cut at 25 to 30 micra in thickness and stained in iodine-crystal violet and in Heidenhain's hæmatoxylin. A 2 per cent, solution of safranin also gave good results. Squash preparations were stained by Feulgen's method. Diplotene stages in Phlœoba were studied from temporary aceto-carmine preparations.
Further Observations on Placental Fusion in Mice, and a Report of a Case in the Rat
Authors: Carr J. G. 
Published: June 2019

An account was previously given of the discovery of two cases of placental fusion in mice, and it was suggested that this condition might occur fairly frequently. This has been amply borne out by subsequent experience, as fourteen other examples have been found while working with mice, and in addition it has once been found in the rat. From this additional material further information about the types of developmental abnormalities that may result from this condition has been gathered. Since the last paper, Owen (1945) has found that commingling of the fœtal circulations in cattle twins can result in the transfer of erythrocyte precursors between partners, resulting in animals exhibiting blood-groups bearing no relation to their genotype. Similar transfers in mice would lead to confusion in many genetic experiments, especially in transplantation experiments with tumours.No genetical basis for the condition is apparent from the data available. It has been, noted in three matings of CBA mice, two of C3H mice, eight C3♂ × CBA♀, and three stock mice, the proportions being roughly related to the relative numbers of each type examined at the time of littering. The frequency is rather less than 1 per cent, of all placentas seen. The only common feature, to which attention was also drawn in the previous paper, has been that the fusion occurred always in conditions of uterine crowding due to large litter size. The smallest litter size in which this fusion was found was five, but in this case five placentas were present in one horn. Whenever labour was observed, it appeared to be difficult and prolonged. Once, by good fortune, delivery was timed approximately. A CBA mouse was found to have delivered two young, and two more were born within the next ten minutes. Nothing further appeared for two hours and ten minutes, when a live pair with fused placentas was delivered with some distress. The last two of the litter, making eight in all, were delivered within twenty minutes of the completion of the birth of the fused pair
The rôle of the gastrointestinal tract in the control of voluntary food intake
Authors: Rayner D. V. , Gregory P. C. 
Published: June 2019

AbstractThe short-term regulation of intake is thought to be achieved at least in part by signals from the gastrointestinal tract. Infusions of glucose, protein hydrolysate or emulsified fat into the stomach, and of glucose or protein hydrolysate into the duodenum, jejunum or ileum caused pigs to reduce their intake to compensate approximately for the energy infused, probably through the regulation of gastric emptying. Protein or protein hydrolysate infusions also caused a long-term inhibition of intake for 30 h by up to three times the energy infused. During feeding gastric emptying occurred at a constant rate of calories, the rate increasing linearly with body weight; duodenal infusion of glucose slowed gastric emptying to compensate for the infused energy and satiety occurred at a reduced food intake but at the same stomach volume. Duodenal infusion of emulsified fat caused a greater than caloric inhibition of intake, which was blocked by the cholecystokinin (CCK) antagonist L-364,718 and appeared to be mediated through a mono-glyceride-induced CCK release. Emulsified fat infused into the duodenum slowed gastric emptying by more than the energy infused and the gastric volume at satiety was decreased suggesting that the effects of fats on intake are possibly independent of gastric emptying. Since L-364,718 did not increase intake on a normal diet (186 g protein, 20 g fat per kg), CCK may only contribute to satiety in pigs eating high-fat diets.
Voluntary food intake of growing pigs
Authors: Cole D. J. A. , Chadd S. A. 
Published: June 2019

AbstractThe amount of food eaten by the pig is a balance between the needs of the animal and the ability of the food to meet those demands. Major factors influencing the needs of the animal are live weight, genotype and sex. Equations have been established to predict the intake of pigs at different live weights but variation exists amongst these equations which reflect a change to genotypes with smaller appetites. Rapid growth may be limited by the appetite of the pig and differences in intake between the sexes are notable, the biggest being castrated males compared with boars and gilts. Intakes of boars and gilts can be similar but often gilts eat slightly more. Dietary energy has a marked effect, with the pig attempting to adjust its daily energy intake by eating less of high-energy diets. The extent to which it can exert this physiological control is limited when a stage is reached where it is unable to compensate by eating more of a low-quality diet because of physical capacity. The influence of protein on intake has received much less attention but there are clear indications that pigs eat less of diets which are very high or very low in crude protein. Intake is also influenced by protein quality and there is evidence from work at the University of Nottingham that quite small variations in lysine level relative to other essential amino acids can markedly affect intake.
The influence of the thermal environment on the voluntary food intake of pigs
Authors: Close W. H. 
Published: June 2019

AbstractThe thermal components of the environment, through their effects on the animals' heat exchange, influence growth, metabolism and voluntary food intake. The environmental components considered include air temperature, either constant or fluctuating, air movement, relative humidity, group size, stocking density and atmospheric concentrations of various gases and dusts. For the growing pig, it has been calculated that each 1°C change in temperature is associated with a 0.65 MJ metabolizable energy (ME) per day change in energy intake; for the other environmental components the variation was between 0.36 and 0.65 MJ ME per day. From the relation between environmental temperatures, food intake and growth, it was shown that for young pigs the optimum temperature range was between 20 and 25°C; for older animals it was between 10 and 20°C. Knowledge of the extent to which food intake changes with the environmental circumstances, both cold and hot, allows feeding and managemental strategies to be developed to ensure optimum growth and efficiency of food utilization.
New approaches to genetic evaluation of beef cattle
Authors: Pollak E. John 
Published: June 2019

The beef cattle industry in the United States has undergone dramatic changes over the past decade with the adoption of genetic evaluation programs. The method of choice has been Henderson's mixed model methodology for best linear unbiased prediction (BLUP). The most prevalently used model is the animal model (Henderson and Quaas, 1976) computed by the equivalent reduced animal model (Quaas and Pollak, 1980).Neither the methodology or the models being used are particularly new. What is new in this industry is the widespread application of these techniques to the analysis of the data banks maintained by the breed organizations. Today many breed associations publish a national sire evaluation, and most of these have published their first in the last three years. This rapid proliferation of published evaluations has coincided with an attitude in the industry of promoting specification beef and predictable performance. Genetic evaluations provide information not only to achieve goals in selection but as well for merchandizing cattle based on quantifiable potential. The enthusiasm for genetic evaluations right now in the U.S. beef industry is high.
Impact of the new statistical technology on pig improvement
Authors: Webb A. J. , Bampton P. R. 
Published: June 2019

AbstractPast improvement programmes in pigs have concentrated on lean growth, and have relied on direct comparisons of contemporaries in a common environment. The new mixed model technology now allows comparisons across environments and generations, and, by utilizing all possible genetic relationships, more accurate prediction of genetic merit for traits of low heritability. In addition, breeding programme design will benefit from more precise estimation of genetic parameters. Principal benefits of the new technology are greater flexibility of structure of breeding programmes, and faster improvement of litter size. The consequence will be larger populations under selection with lower costs per unit of genetic improvement. For national improvement schemes using a high proportion of AI matings, central testing stations could become unnecessary. Main research priorities are the optimum family structure to balance selection and inbreeding, more efficient computing strategies for large numbers of traits, and the incorporation of single genes into predictions of merit. The new technology will be important for the exploitation of biological advances in manipulation of both reproduction and the genome.
Long-term selection for meat production in poultry
Authors: Siegel P. B. , Dunnington E. A. 
Published: June 2019

ABSTRACTSelection for meat production in poultry includes commercial development of meat-type chickens, turkeys and waterfowl and laboratory studies that involve these types of poultry. Heritabilities for growth traits are moderate to high, enabling response to selection for these traits. Changes in growth traits result in correlated responses in feed intake and have a negative relationship with reproductive traits. That is, deviations from intermediate growth rates are deleterious to reproduction. In this paper we discuss genetic aspects of poultry meat production and long-term laboratory selection experiments for growth. Emphasis is given to the species with the most extensive research base, the chicken.
2.1 Data Recording
Authors: Burgess A. D. 
Published: June 2019

Computers or computing devices are in use, and will be in use in the future to a greater extent, in the interest of animal production. Data collection, in one form or another, is fundamental to that usage. The ready availability of low cost digital processors, data converters and signal amplifiers, where appropriate, has ensured that this is so. The only constraint is with the difficulty of measurement and, in signal recording, whether suitable instrumentation devices or transducers exist or can be devised.The important considerations are why the data are needed, how many data, when and in what form they are required.From the answer to these questions will come as many diverse forms of data recording — albeit based on established techniques — as there are requirements to record, all of which may be realized using the same basic hardware components by virtue of the flexibility introduced by the need to program the processing element. In the manner of pure research, the answers to these questions constitute the design of the experiment, which too easily can be ill-considered, resulting in quantities of data useless to its original intent; where automation is considered, they constitute the design of the digital system required.The range of requirements for data recording extends from manual keyboard entry to small computers engaged in farm management, through the systems designed to gather data automatically for the management of animal enterprises, to the specialized requirements for data to substantiate mathematical models of particular physiological processes in the animal. Within this range, the variation of requirement is fundamentally that of its dependancy upon the dimension of time.
4.4 A Policy for Encouraging the Effective Use of Computers in Animal Production Development
Authors: Whittemore C. T. 
Published: June 2019

In addition to data and record handling and the completion of complex and arduous mathematical calculations, the computer may serve a wide range of purposes for the agricultural industry; these include the provision of day-to-day management information, the mechanical enactment of management decisions, business forecasting, interpretation of real life and prediction of future response by use of simulation models, analysis of cost effectiveness of various tactics and stratagems, the transfer of information, scrutinization of existing knowledge and the formulation of experimental programmes. The computer is seen as a major linking medium between research, development and production practice; being both the preferred route for information flow and an ideal way of packaging dispersed pieces of knowledge into practical, usable, systems advice.The concern of practical producers is not with discrete little problems but with systems. To help, the extension worker must bring forward systems solutions. Often research and development workers try to get across to producers potential benefits in small bits (3 times daily milking gives a yield lift of 15%; flat rate feeding gives better margins over concentrates; high density diets improve feed efficiency), whereas producer benefits come from the cost effectiveness of whole integrated systems.
Perspectives of animal nutrition with efficient use of by-products and wastes
Authors: Raymond W. F. 
Published: June 2019

The preparation of the introductory paper to this Conference has presented two particular problems. First, as always, there was the risk that it would contain too many references to aspects which would be dealt with in greater detail — and possibly contradicted subsequently. Secondly, the title of the Conference, ‘By-Products and Wastes in Animal Feeding’, seemed to be at variance with a definition of waste, ‘a resource arising (in agriculture) where the cost and complexity of using that resource is greater than the returns from using it’, which I had used at a similar Conference a year ago (Raymond, 1977) and which might imply that ‘waste’, once utilized, is no longer ‘waste’. But this is really semantics; the aim of this Conference is to bring together the latest information on whether resources which have conventionally been considered ‘wastes’ can effectively and economically be utilized in new animal feeding systems. The concept of economic use is vital. I strongly believe that we must reject the idea that there is some sort of moral imperative to use wastes; if this is not economic then their use must involve the misuse of some other resource within the total production system.The situation is of course dynamic; effective research and development (R and D) can transform yesterday's waste resource into a new productive asset. Further, the economic environment is not static; for example, changes in relative costs of feedstuffs mean that farmers will this winter feed large quantities of straw which in 1972 they would have burnt in the field, while high cereal prices mean that more non-tariff components, including by-products, are now being included in least-cost livestock rations. Thus it is worth examining some of the factors that have led to the current interest in the role of by-products and waste materials in animal feeding setting aside any marginal objection to this use of ‘waste’.
By-products from the food and dairy industries
Authors: Singer D. D. 
Published: June 2019

For the purpose of this paper I intend to include within the term ‘by-products’ all those materials that arise from the food industries which are not consumed by the human population of the United Kingdom. Some of these materials are not acceptable as part of the human diet, or, if acceptable, find no ready market. Other materials are inedible, perhaps by humans and other animals, but can be converted into acceptable food or feed whilst yet others which are edible and acceptable are wasted in processing, storage, transport, distribution and in the kitchen and dining room. It is impossible to give a figure for the annual amount of by-products and waste available but statistical evidence points to approximately 6 million tonnes of food, all of which is edible but not consumed. This figure does not include by-products which are not intended for human consumption such as abattoir wastes, whey and brewery wastes and cereal offals. The total figure is therefore larger and represents a considerable potential economic resource. (It must be observed however, that only a small fraction of these wastes and by-products can be economically utilized. Other speakers are dealing with animal slaughter, fish and cereal wastes and I will therefore give only passing attention to these materials.)About 40 million gallons of cheese whey are produced in the UK each year on the farm. Of this, about 12 million gallons are fed directly to pigs. Although it appears that heavy hog production and cheese making are often associated, disposal of whey on farm remains a problem, since the price fetched by whey may be only a quarter or less than the cost of transport. Disposal on land, where it can be useful as a fertilizer, can lead to pollution problems. Trials carried out by ADAS (Wolverhampton) on both beef and dairy cattle are promising. It has been shown that every kg of barley previously fed to dairy cattle can be replaced by 10 litres of whey at half the cost, making barley feed unnecessary. In diets for steers, calculations have shown that a litre of whey at 6% solids can replace 90g of compound for energy (Peacock, 1977).