Morphogenetic studies of a genetically controlled tumor-like condition in Lycopersicon hybrids

Summary A dominant tumor-like condition recently isolated in a tomato hybrid is described from the viewpoint of morphogenesis. Tumors, consisting of masses of enlarged parenchymatous cells, generally appear on the ventral surface of the third leaf and the subsequently formed leaves of the hybrid derivatives. These outgrowths do not differentiate into teratomas. Abortive floral buds develop under greenhouse conditions and the tumorous plants are much dwarfed compared to the normal segregants of the same population. the same tumor genotype behaves differently under the field conditions: it grows and blossoms like the normal plants, setting fruits with viable seeds, and tumors fail to develop. Thus, tumor expression and general morphology of the tumor plants are greatly modified by environmental conditions.Tissue culture studies employing a variety of media have shown that tissues excised from tumor-producing plants are not autonomous with respect to growth hormones, nor are tissues from the non-tumorous segregants. Nevertheless, tissues from tumor and non-tumor genotypes show different growth requirements. Tumor and non-tumor tomatoes can thus be distinguished on the basis of in vitro growth responses, a result consistent with their different genetic constitution. Differentiation of buds or roots was not observed in either type of tissue.Abbreviations used GA gibberellic acid - IAA 3-indoleacetic acid - 2.4-D 2.4-dichlorophenoxyacetic acid Work Supported by National Science Foundation Grant GB-3198 and funds from The Cairncrest Foundation.     

The Hypothalamic-Pituitary-Adrenocortical System—Clinical Evaluation by Pharmacologic Techniques

The hypothalamic-pituitary-adrenocortical system is a complex negative feed-back control mechanism. Under non-stress conditions it functions to maintain a circadian rhythm of adrenal steroid production which is secondary to a circadian fluctuation in the sensitivity to suppression of acth by hydrocortisone. Any stressful stimulus causes an augmentation of steroid production which is due in part to a decrease in sensitivity of acth to suppression. Aldosterone production is not primarily controlled by acth.The increased understanding of this system and of its pathologic alterations has led to the development of a number of pharmacologic techniques which have proved most valuable in evaluating its integrity. Hypothalamic-pituitary function can be assessed by the response to the administration of dexamethasone, methopyrapone, bacterial pyrogen and vasopressin. Adrenal cortical function can be assessed by the response to acth, dexamethasone and spironolactone.     

"Necking" behaviour in the giraffe

Previous references to "necking" behaviour, and the main features of the study area are briefly outlined.
"Necking" behaviour in giraffe takes place only in all male herds. When the animals are in a head to head posture the intensity is either high or low, but when animals take up a head to tail posture the actions are always of high intensity and appear to have greater sexual significance.
The significance of "necking" is discussed, and it is suggested that these ritualized actions form an important sexuo-social bonding mechanism whereby a hierarchy is created amongst the males, and movement between strictly bachelor and mixed herds helps to maintain contact between the sexes in this polygamous mammal.     

Applicants to Canadian Medical Schools for 1966-67

An examination of applicants to Canadian medical schools for 1966-67 revealed that 4534 applications were received for the approximately 974 available places. The number of Canadian applications was 2866 and these were made by 1815 individual applicants, an increase of 48 over 1965-66. United States applicants declined from 1143 to 1013.Evaluations made by the schools concerning the acceptability of the Canadian applicants disclosed that 55 applicants who rated as “acceptable” by one or more schools failed to gain admission to any medical school in 1966-67 (as compared to 36 in 1965-66). However, of those applicants who did find a place 76 were evaluated as “marginal” or “unacceptable”, while another 126 were rated as “acceptable” by one school but “marginal” and/or “acceptable” by one or more other schools.These results were interpreted to imply that the Canadian medical schools were still experiencing difficulty in attracting well-qualified applicants for study in medicine.     

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The levels of individual free and conjugated ecdysteroids and ecdysteroid acids, labeled from [¹⁴C]cholesterol, in five different age groups of male Manduca sexta during pupal-adult development were determined by HPLC. Eight free ecdysteroids, eight ecdysteroid phosphates, and two ecdysteroid acids were identified. Newly ecdysed pupae contained predominantly 3-epiecdysteroids in each of the free, conjugated, and acidic ecdysteroid fractions. The titer of each ecdysteroid fraction rose sharply by day 4, and this was particularly noteworthy with respect to free ecdysone and 3-epi-20-hydroxyecdysonoic acid. This stage demonstrated high degrees of ecdysone biosynthesis, oxidative catabolism, and phosphorylation. As development proceeded to day 16, total ecdysteroid titer remained constant; a decreasing free ecdysteroid titer was accompanieid by increasing titers of both conjugates and acids resulting from the metabolic processes of hydroxylation, oxidation, epimerization, and phosphorylation. The predominant metabolites throughout development were 3-epi-20-hydroxyecdysonoic acid and the phosphate conjugates of 3-epi-20-hydroxyecdysone and 3-epi-20,26-dihydroxyecdysone. The ultimate inactivation of the ecdysteroids of M. sexta during pupal-adult development is possibly mediated by two pairs of metabolically-linked processes, one leading to a 3-epiecdysteroid acid, and the other to 3-epiecdysteroid phosphates.     

Pheromone-mediated sexual selection in the mothUtetheisa ornatrix: Olfactory receptor neurons responsive to a male-produced pheromone

Male Utetheisa ornatrixhave a pair of eversible glandular brushes (coremata) which are displayed during precopulatory interactions with the female. Earlier studies have shown that a pheromone associated with the coremata, hydroxydanaidal (HD), is derived by the males from pyrrolizidine alkaloids (PAs) that they sequester as larvae from their foodplants (Crotalariaspp.) The PAs impart a distastefulness upon Utetheisathat protects both larvae and adults against predation. The receptor neurons specialized for detection of HD are housed in sensilla whose morphological features, as revealed by scanning electron microscopy, classify them as sensilla basiconica. The sensitivity and dynamic range of these receptor neurons were largely unaffected by whether the females were raised on an alkaloid-free diet or on a diet supplemented with Crotalariaseeds. Acetylation of the hydroxyl group of HD substantially reduced the activity of the molecule. None of the antennal sensilla examined contained receptor neurons sensitive to a PA (monocrotaline) or its N-oxide.