Ichthyosis fetalis in Polled Hereford and Shorthorn calves
Inherited forms of ichthyosis, or generalized scaling of the skin, have been reported in many animal species, including cattle, and are characterized by an autosomal recessive mode of inheritance. We investigated 2 calves affected with ichthyosis fetalis, a Polled Hereford and a Shorthorn. Both cases had hard white plaques on the skin consistent with excessive keratinization. This was confirmed by histopathology, which showed severe diffuse epidermal and follicular orthokeratotic hyperkeratosis. The known mutation (H1935R) in gene ABCA12, responsible for ichthyosis fetalis in Chianina cattle, was shown to be absent in both affected calves and their obligate heterozygous parents. These molecular findings indicate that allelic heterogeneity exists for this condition in cattle.
Integumentary System
1. Explain why the skin is called the cutaneous membrane. 2. Name the layers of the skin, describe the structure (tissues) of each, and name a general function of each. 3. Discuss the four cell types present in the epidermis. 4. List the four/five layers of the epidermis and explain the process of keratinization. 5. Explain the protective role of keratin, and in turn, the epidermis. 6. Name the pigment responsible for skin and hair color, and explain how people of different races (i.e. and skin color) differ in regards to it, and the cell that produces it. 7. List some factors that promote the production of melanin (besides DNA). 8. Distinguish between the papillary layer and reticular layer of the dermis, and locate the appropriate sensory receptor in each of these layers. 9. Compare and contrast Meissner's and Pacinian Corpuscle's in terms of their structure, function, and location. 10. Describe the structure and function of the subcutaneous layer. 11. Explain what is meant by the term epidermal derivative, and list four examples. 12. Describe the general structure of a hair follicle and identify two other structures that are always associated with them. 13. Distinguish between merocrine (eccrine) and apocrine sweat glands in terms of structure, secretion content and odor, activation, and major body locations. 14. Name two modified apocrine glands of the skin.
Temperature effects on lily development rate and morphology from the visible bud stage until anthesis.
Day (DT) and night temperatures (NT) influenced Lilium longiflorum Thunb. 'Nellie White' stem elongation and development rate from the visible bud stage (VB) until anthesis. Plant height increase after VB was a function of the difference (DIF) between DT and NT (DT-NT). Plant height increased 90% as DIF increased from - 16 to 16C. A cubic model described bud development rate as a function of temperature from 14 to 30C. A linear model adequately described bud development rate as a function of average daily temperature from 14 to 21C. Based on the linear model, bud development rate increased 0.05 per day for each 1C increase in average daily temperature. The base temperature for bud development, i.e., the temperature at which bud development rate was 0, was calculated as 3.5C. Greenhouse forcing of vernalized Easter lilies is commonly divided into three phases: I) placement of vernalized bulbs in the greenhouse to flower initiation, II) flower initiation to VB, and III) VB to anthesis (De Hertogh and Wilkins, 1971). Plant morphological development differs during each of the forcing phases (De Hertogh and Wilkins, 1971). Growth during phase I is vegetative and consists of stem elongation and leaf expan- sion. Flower initiation, leaf expansion, and stem elongation oc- cur during phase II. Inflorescence expansion and stem elongation occur during phase III. Lily responses to temperature during phase III differed from those during phases I and II (Wang and Roberts, 1983). Lily development rate, quantified as days to unfold a leaf, is a de- creasing linear function of average daily temperature between 14 and 30C during phases I and II (Karlsson et al., 1988). Lily development rate during phase III is a nonlinear function of temperature (Healy and Wilkins, 1984). The effect of temper- ature on the rate of lily development decreases as DT and/or NT increase during phase III (Rob and Wilkins, 1973; Healy and Wilkins, 1984). Easter lily morphological development is thermomorpho- genie. For instance, internode length increases as the DIF be- tween DT and NT increases (Erwin et al., 1989). In addition, leaf orientation, leaf length, and flower length are also influ- enced by diurnal changes in temperature.