Lethal effect of attached-X deletion in Drosophila melanogaster

Attached-X stocks appear to be deficient in a small region, probably heterochromatic, which is normally covered by an homologous region on the short arm of the Y chromosome. There is an homologous deficiency in the ec dx stock Y chromosome. When this Ys deficiency occurs in crosses involving attached-X stocks, the matroclinous females are not recovered.

The development of lesions in vitamin A-deficient adult fowl

Twenty-five cocks aged 7 months and 43 hens aged 18 months had been fed from hatching diets free from retinol but supplemented with retinoic acid. The retinoic acid supplement was withdrawn from 20 cocks and 23 hens and the birds developed signs of vitamin A deficiency. The deficient birds together with control birds fed retinyl acetate were killed and examined at intervals throughout the 18 days of the experiment. Observations were made on clinical signs; changes in tissues, particularly nasal epithelium, nervous system and bone, and cerebrospinal fluid pressures were recorded. The behaviour of the deficient birds was abnormal by the 3rd day of the experiment, a degree of incoordination was seen after the 6th day, and by the 10th day the weight of the deficient birds was significantly lower than that of the controls. Changes in nasal epithelium and in the periosteum lining the cranial cavity and vertebral canal were seen by the 3rd day of the experiment and after 6 days new spicules of bone were being formed. Compression of central nervous system and nerve fibre degeneration were well established by the 10th day. Dramatic changes in the cerebrospinal fluid pressure were not seen. Only 2 deficient birds had values outside the normal range and these were both recorded at the end of the experiment. These results are discussed and we conclude that the CNS compression is related to the increased deposition of periosteal bone.

Hypervitaminosis A in the chick

Images

Observations on the lesions in vitamin A deficient adult fowls with particular reference to changes in bone and central nervous system

Images

Lesions associated with the developing of ataxia in vitamin A-deficient chicks

1. An investigation was made of the sequence of changes that occurred during the development of vitamin A deficiency in the chick. Particular attention was given to changes in the central nervous system (CNS) and in bone.

2. Groups of birds were killed after being fed the diet for 14, 17, 20, 22, 24 and 28 days. The tissues of five deficient and five control birds were examined unfixed for gross changes and photographed. Groups of five deficient and five control chicks were perfused through the heart with Heidenhainαs Susa solution and, after decalcification, the tissues were examined for gross and histological changes. The bones of other groups of five deficient and five control chicks were examined for tetracycline-induced fluorescence.

3. The first lesion seen was metaplasia of the nasal respiratory epithelium to a stratified squamous form. This was rapidly followed be decreased weight gain, the development of ataxia, compression of the CNS and Wallerian degeneration in the ventral and lateral columns of the cervical spinal cord.

4. Changes in bone were first seen in chicks killed 6 days after metaplasia of nasal respiratory epithelium and 3 days after ataxia and brain compression had been seen.

5. Changes were present in the epiphyseal cartilage zone of the femur and in the periosteum of the vertebrae, but not in the epiphyseal cartilage of the vertebrae. the changes in the femur were thought not to have a direct relationship to vitamin A deficiency and may have been produced by inanition.

6. An increase in osteoblast activity and cartilage formation was seen in the vertebral periosteum of the vitamin A-deficient chicks and the relationship of these changes to lesions in the CNS is discussed.

Reproduction and vision in rats maintained on a retinol-free diet containing 3-dehydroretinol (vitamin A2)

1. Seventeen hooded female rats were given from weaning a retinol-free diet containing methyl retinoate. When 105 days old they were mated with normal bucks.

2. Six of these rats were subsequently given dietary supplements of 100 μg retinol daily and another six were given 100 μg 3-dehydroretinol daily. All twelve rats had litters.

3. The five rats that received only methylretinoate during pregnancy resorbed their foetuses.

4. One of the litters from the female rats given 3-dehydroretinol consisted of six male pups. These young rats had never had access to retinol. They were maintained on a retinol-free diet supplemented with methyl retinoate. Two of these rats were given daily supplements of 3-dehydroretinol and another pair were given daily an equal amount of retinol.

5. The six rats were killed when 195 days old. The testes and the retina of the rats given either 3-dehydroretinol or retinol were normal. The testes and the retina of the rats given methylretinoate only were degenerate.

Changes in the tissues of guinea-pigs fed on a diet free from vitamin A but containing methyl retinoate

1. Forty-eight guinea-pigs were fed from weaning on a semi-synthetic diet free of retinol and carotenoids. Twenty-two of these animals received a twice-weekly supplement of methyl retinoate and fifteen received a twice-weekly supplement of retinyl acetate. The remaining eleven animals were fed on the vitamin A-free diet without supplementation.

2. At varying times throughout the experiment, animals died or were killed by chloroform inhalation. Testes and seminal vesicles were weighed and these tissues together with trachea, lungs, salivary glands, bladder, eyes and vagina were examined histologically.

3. The eleven guinea-pigs that received the unsupplemented diet developed signs of vitamin A deficiency after being fed on the diet for 3 or 4 weeks. Many epithelia showed a metaplastic change to the stratified squamous form often with keratinization.

4. The guinea-pigs given supplements of either methyl retinoate or retinyl acetate grew at a normal rate and developed none of the signs of vitamin A deficiency that appeared in the animals on the unsupplemented diet. Evidence of metaplastic change in epithelia was not seen in any of these animals.

5. Thirteen males were fed on the deficient diet and methyl retinoate. The testicles and seminal vesicles of these animals weighed less than those of the ten males fed on the deficient diet and retinyl acetate. The testes of the former showed severe histological degeneration of the seminiferous epithelium. The testes of the guinea-pigs fed on retinyl acetate were normal.

6. Fifteen guinea-pigs fed on the deficient diet and retinyl acetate were mated to normal males. Eleven were thought to have become pregant. Eight of these gave birth to twenty-four pups. One died in advanced pregnancy with five apparently normal pups in utero and one produced three living young and died with one still in utero. Sixteen guinea-pigs fed on the deficient diet and methyl retinoate were mated to normal males. Twelve were thought to have conceived but all resorbed their foetuses.

7. The vision of guinea-pigs fed on the synthetic diet and methyl retinoate deteriorated progressively, and after 150 days on the experiment the pupils did not respond to light. However, degeneration of the retina, such as had been seen in rats fed on a vitamin A-deficient diet containing methyl retinoate, was not seen in any of the guinea-pigs.