The effect of inbreeding on the BB/W diabetic rat

The Worcester colony of BB/W diabetic rats has been inbred by brother X sister matings for 12 generations. The litter size at both birth and weaning was dependent on whether the female was normal or diabetic. At the beginning of the inbreeding, the normal females produced 2.1 more young per litter than did the diabetic females, but the eleventh generation of inbreeding this difference had been reduced to 0.68 young. Diabetic males had little influence on litter size. At weaning, the normal mothers had raised litters that had 3.64 more young than the diabetics in the early generations, but this had dropped to 1.48 in later generations. After 11 generations of inbreeding, there was a 1.95 decrease in litter size from normal matings, but only a 0.86 decrease from diabetic matings. The average loss from birth to weaning was one pup for normal females and two pups for diabetic females. The time of onset (median 85 days) has not changed with inbreeding, nor is the onset pattern and severity different in any of the nine inbred lines. The penetrance in the D X D matings did change from 45% in the first five generations to 60% in the next six, but there has been no significant change in generations 6 through 11. Inbreeding changed the results obtained from outcrossing to nondiabetic lines. All crosses produced no diabetics in the F1, but noninbreds produced less than 2% in the F2 and 4% in the BC, whereas inbreds produced 18 to 32% in the BCs. These latter figures are consistent with the ratio of 7:3 expected with 60% penetrance.

Modulation of proline-rich protein biosynthesis in rat parotid glands by sorghums with high tannin levels

Feeding of sorghum with a high level of tannin (high-tannin sorghum) to rats caused changes in gene expression in parotid glands similar to isoproterenol treatment. Within 3 days the parotid glands were enlarged about 3-fold and a series of proline-rich proteins were increased about 12-fold. Unlike isoproterenol treatment, no changes were observed in the submandibular glands, and a Mr 220,000 glycoprotein in parotid glands was not induced. Amino acid analyses, electrophoretic patterns, and cell-free translations of mRNAs all confirmed that the proline-rich proteins induced by feeding high-tannin sorghum were identical to those induced by isoproterenol treatment. Binding curves for proline-rich proteins to tannins showed affinities 10-fold greater than bovine serum albumin and tannins.

Applicability of Bender-Gestalt emotional indicators for emotionally disturbed and nonreferred students

30 emotionally disturbed and 29 nonreferred elementary school-aged students were administered the Bender-Gestalt. Protocols were analyzed for developmental age and 12 emotional indicators. Present groups did not differ significantly in total number of indicators even when chronological age and Bender age were covaried, confirming Koppitz's analysis. Small but significant correlations were noted between total number of indicators and age.

Genetic analysis of the BB/W diabetic rat

A large colony of BB/W diabetic rats has been developed as a research model for insulin dependent, type 1 diabetes mellitus. The foundation stock had 8% diabetics which appeared in a sporadic manner. The Worcester (W) colony was inbred by brother X sister matings for 11 generations and the proportion of diabetics increased to over 50%. The age of detection varies from 46 to 250 days. For selection purposes, classification was made at 120 days, which means that 15 to 20% potential diabetics were classified as normal. Evidence from different analyses indicates that the inheritance of diabetes is by a recessive gene or gene cluster with 50% penetrance at 120 days. The selection of breeding stock from diabetic parents raised the proportion of diabetics produced by two normal parents from 12 to 43%. Diallel tests show that diabetic and normal offspring of two diabetic parents have the same diabetic genotype. Outcrosses to other strains of rat indicate that the trait is transferred as a recessive with only 3% diabetics recovered in the F2 where noninbred BB stock was used as the diabetic source, and 36% where partially inbred BB/W was used as the diabetic parent. Since the proportion of diabetics produced by all types of crosses has changed, and may continue to change with changes in the genetic background, we have used the operational term penetrance to describe the frequency of diabetes in individuals homozygous for the diabetes gene cluster. At present the penetrance at 120 days is 59% in the BB/W colony.

Spontaneous autoimmune diabetes mellitus in the BB rat

The BioBreeding Rat is a recently discovered model of spontaneous diabetes mellitus. Studies to date have revealed the following characteristics of the syndrome: genetic predisposition, equal frequency and severity among males and females, absence of obesity, life sustaining requirement for insulin therapy, lymphocytic insulitis with destruction of pancreatic beta-cells, lymphocytic thyroiditis and the presence of autoantibodies to smooth muscle, thyroid colloid and other cellular antigens. Animals raised in a germ-free environment evidence diabetes with equal frequency and severity. Support for a cell-mediated autoimmune pathogenesis of the diabetic syndrome is derived from the following experiments: administration of antiserum to rat lymphocytes prevents diabetes in susceptible animals and normalizes plasma glucose levels in 36% of diabetic rats; neonatal thymectomy almost completely prevents the occurrence of diabetes. Although the BB rat may not be an appropriate model for studying the vascular complications of diabetes, peripheral nerve functional and ultrastructural defects have been reported and renal glomerular immuneglobulin deposits have been observed in long-term diabetic animals.

Retrieval of the critically ill in South Australia: a coordinated approach

A system is described for the stabilization and evacuation of the critically ill in South Australia, with a discussion of experience in 278 patients. The integration of activities of peripheral medical practitioners, major teaching hospitals, and the ambulance transport authority (St John Ambulance Council) is paramount. Modes of communication are by "urgent line" telephone and radio. Advanced life-support equipment is portable, may be placed in any ambulance vehicle, and is used and maintained principally by the staff of intensive care units. The design characteristics of a suitable road vehicle and fixed-wing aircraft are considered, with emphasis on dimensions for the particular needs of advanced life-support. The cost of transporting such a patient is approximately two-thirds of an average bed day cost in a public hospital, plus the basic ambulance charge. The number of patients who need such measures is 0.2% of the total number of patients carried by ambulance per annum.

Recombination values and their errors

Two four-point testcrosses comprising 87,000 tomato plants were grown and the data collected from 28 subgroups. Each subgroup consisted of 2,000 or 5,000 plants and should give a valid estimate of the three recombination values. The 28 values for each interval give more outlyers (23% are outside the 95% limits set by the standard deviation calculated by the binomial formula square root of p q/n) than would be expected by chance. If each subgroup was regarded as the control and the other groups tested against this, then 42% of the time the two subgroups would be significantly different. It is suggested that there are many cases in the literature where this comparison has been made and the significant difference wrongly ascribed to treatment. While the causes of these changes in recombination value are unknown and therefore uncontrollable, they must be anticipated in all such studies. Control and treatment must be replicated enough that chance extreme values will not be attributed to treatment.

The inheritance of glucosuria in the KK and A y mouse

Both the KK and the Ay mouse exhibit many symptoms of diabetes. Glucosuria is the most satisfactory test for this condition in mice. Glucosuria is inherited as a dominant in both strains, but many factors reduce its penetrance. The penetrance in the KK strain can be increased from 23 to 62% by crossing to C57BL/10J and then selecting the most effective background modifiers. The number of modifiers must be small because response was rapid and fixation fast. The cross KK × Ay gives yellow and black offspring in equal numbers. The yellows have the dominant genes for glucosuria from both strains, and the males all become glucosuric by the time they are 8 months old, in comparison to 7% of the males in the parental yellow strain. Of the yellow females, 88% are glucosuric by 1 year in comparion to 0% of the yellow strain or 2% of the KK's. The black males which lack the gene from the Ay strain but do have the gene from the KK have no glucosurics at 8 months and only 2% at 1 year. The F1 of the cross KK × Ay provides valuable research material since all yellow males will become glucosuric by 8 months of age and none of their black litter mates will.

Acid phosphatase during development of the black carpet beetle Attagenus megatoma (Fab.)

The specific activity for free and bound fractions of acid phosphatase revealed age-dependent alterations during the development of the black carpet beetle, Attagenus megatoma (Fab.). Both fractions exhibited highest activity at the pupal stage. The specific activity appears to be related to the biology of the organism.

The productivity of four inbred strains of Drosophila melanogaster

Four inbred strains of flies have been maintained by brother × sister mating since November, 1963. Counts of production per vial were made at 14 days, and the flies from the most productive vial were used as the parents of the next generation. For analysis the data were separated into three groups: vials with no production (blanks), vials with less than 20 flies (low production), and those with over 20 flies. The number of blanks did not change significantly in strain A but did show significant decreases in strains B and D. Until generation 60 the number of blanks per generation was not distributed in a Poisson series, but after this generation it was. The number of vials with low production was high in all strains for the first 20 generations and then decreased in widely different generations for each strain.Changes took place in all four strains but by different mechanisms. In strain A there was no increase in range, but the mode moved from 40 to 150 flies per vial and the proportion of low productive vials fell from 15% to 2% per generation. In strain D the low production vials fell from 22% to 6% and there was an extension of the range. Each of the strains shows definite trends of increase and decrease which last from 3 to 30 generations, and vary in slope from 0.3 to 13.8 flies per vial per generation. While we cannot determine how much or how many of these slopes are environmental, it can be argued that since many of the slopes of the four strains are not correlated, part of the cause is genetic. The changes in the direction of the trends show that phenotypic selection in small populations was not effective in accumulating and exploiting mutations for greater productivity.

FIVE GENES LOCATED ON CHROMOSOME 4 OF THE TOMATO

The gene for broadleaf has been the only gene known to be on chromosome 4 of the tomato. Four other genes are shown to be linked with broadleaf. These are wiry (w1), which distorts the leaves and flowers; clausa (clau), which causes excessive proliferation of the pinnae; divergens (di) which affects plant growth and stem color; and stamenless (sl1), which causes the stamens to be absent or greatly reduced. The genes w1, clau, and di give mongenic ratios which are deficient in number of mutants. The order of the genes on the basis of F2 data is w1clau 39 e 21 di 2 sl1. The genes tf, ao, rv, and ah are not in this group.

PERIODICITIES IN THE ANNUAL MUSKRAT POPULATION FIGURES FOR THE PROVINCE OF SASKATCHEWAN

The yearly production of muskrat pelts in Saskatchewan for the period 1915–60 exhibits a 6-year periodicity instead of the expected 10-year cycle. To check the synchrony of these periodicities, the province is divided into thirds: the southern prairie section, the middle aspen grove section, and the northern Canadian Shield section. In the prairie section there are two main peaks, one in 1923 and the other in 1955. The remainder of the peaks, which are at 6-year intervals, vary greatly in magnitude. The aspen grove section has peaks which are also 6 years apart but are of similar magnitude. The northern section has peaks of equal magnitude which are 30 years apart. The environmental control exercised on the conservation blocks in the Cumberland House area tends to disrupt the cycle.Some of the population changes are correlated with precipitation data. In the prairie section, the highest catches occur after 2 wet years. In the other sections, the muskrat population is not correlated with the precipitation. In the aspen grove section there is a slight correlation between snowfall and the muskrat catch the next spring.

THE INHERITANCE OF LITTER SIZE, BODY WEIGHT, AND VARIABILITY, IN A CROSS BETWEEN TWO INBRED STRAINS OF MICE

Crosses were made between the two inbred lines, C57BL and BALB, and the effects of maternity and genotype on litter size, survival, 30- and 60-day weights, and their variances were assessed. The maternal effect of BALB reduced litter size by.78 to 1.91 when compared with reciprocal crosses of identical genotype. No maternal effect was found for C57; neither did the genotype of the young have any effect on the litter size borne by mothers of this strain. There was a significant increase (2.26 ±.67) in litter size when BALB females produced hybrid instead of inbred young. This was not the result of hybrid males being more prolific, because BALB males mated to non-BALB females produced the largest litters in this experiment. The cross F1 × F1produced the largest mean litter size. A change in ration affected the litter size when BALB was the mother, but not when C57 was the mother. Fox chow plus linseed produced more young than any of the other three diets.There were no significant differences in the weights of males of any of the generations at 30 days, but the F1females borne in C57 mothers were larger than the females of other generations, and it appears that the C57 female exerts a maternal effect which causes the female young to mature earlier. The data indicate that the mother exerts the greatest influence on 30-day weights, the genotype of the young having little or no effect. The F1female has the greatest maternal effect: she increases the 30-day weight by 10–20%.At 60 days the F1mouse was 15% larger than the corresponding inbred borne in the same female. The mean weights of the F1and F2were the same, but the backcrosses were 10% lighter.The variance at 30 days was larger than the corresponding variance at 60 days, and 90% of the variance was in the between-litters component. At 30 days the largest variances were found in the P1, F1, and B.C. generations, while the smallest was found in the F2indicating that much of the variability was the result of the maternal environment. At 60 days the variances for all generations were essentially the same.MacArthur's large and small strains, which had been produced by 30 generations of selection with only moderate inbreeding, were carried through 20 generations of brother × sister mating. This inbreeding brought about a decrease in the weight of the large line, and an increase in the weights of the small strain. The former may be attributed to the loss of the heterozygotic effect on size, while the latter may be the result of natural counterselection; the smallest mice had few or no young.