Incubation temperature impacts nestling growth and survival in an open‐cup nesting passerine

For oviparous species such as birds, conditions experienced while in the egg can have long‐lasting effects on the individual. The impact of subtle changes in incubation temperature on nestling development, however, remains poorly understood, especially for open‐cup nesting species with altricial young. To investigate how incubation temperature affects nestling development and survival in such species, we artificially incubated American robin (Turdus migratorius) eggs at 36.1°C (“Low” treatment) and 37.8°C (“High” treatment). Chicks were fostered to same‐age nests upon hatching, and we measured mass, tarsus, and wing length of experimental nestlings and one randomly selected, naturally incubated (“Natural”), foster nest‐mate on days 7 and 10 posthatch. We found significant effects of incubation temperature on incubation duration, growth, and survival, in which experimentally incubated nestlings had shorter incubation periods (10.22, 11.50, and 11.95 days for High, Low, and Natural eggs, respectively), and nestlings from the Low treatment were smaller and had reduced survival compared to High and Natural nestlings. These results highlight the importance of incubation conditions during embryonic development for incubation duration, somatic development, and survival. Moreover, these findings indicate that differences in incubation temperature within the natural range of variation can have important carryover effects on growth and survival in species with altricial young.     

Dysanaptic growth of conducting airways after pneumonectomy assessed by CT scan.

In immature dogs after pneumonectomy (PNX), pulmonary viscous resistance is persistently elevated predominantly as a result of a high airway resistance (Raw). We examined the anatomical basis for this observation by using computerized tomography scans obtained from foxhounds 4-10 mo after right PNX. Airways of the left lower lobe were followed from generations z = 0 (trachea) to z = 12. By 4 mo post-PNX, airway length increased significantly relative to sham-operated dogs, but airway cross-sectional area (CSA) did not. By 10 mo post-PNX, average airway CSA was 24% above that in controls. Theoretically, the increased airway length and CSA should reduce lobar Raw by 50%. However, post-PNX airway dilatation did not normalize total CSA, and estimated resistance due to turbulence and convective acceleration increased threefold; i.e., the 50% reduction in lobar Raw would be offset by the loss of four of seven lobes. Thus the expected reduction in work of breathing in the whole animal is only ~30%, consistent with previously measured work of breathing in pneumonectomized dogs. We conclude that airway structure adapts slowly and incompletely, resulting in limited functional compensation.     

Photosynthesis and respiration in a fast growing strain of Gigartina exasperata (Harvey and Bailey)

Photosynthesis and respiration rates of blades from a selected, fast growing strain of the marine red alga. Gigartina exasperata Harvey and Bailey, a carrageenan producer, were measured with an oxygen electrode and compared with rates similarly obtained from wild material of the same species. The measurements, expressed as μl O₂ · mg chl a^?1, min^?1. were made over a light intensity range from 5 to 800 μE · m^?2 · sec^?1 and a temperature range of 6 to 16°C. The photosynthesis light intensity data are best described by hyperbolic functions.     

Spatial decomposition of predation risk using resource selection functions: an example in a wolf–elk predator–prey system

Predation is a fundamental ecological and evolutionary process that varies in space, and the avoidance of predation risk is of central importance in foraging theory. While there has been a recent growth of approaches to spatially model predation risk, these approaches lack an adequate mechanistic framework that can be applied to real landscapes. In this paper we show how predation risk can be decomposed into encounter and attack stages, and modeled spatially using resource selection functions (RSF) and resource selection probability functions (RSPF). We use this approach to compare the effects of landscape attributes on the relative probability of encounter, the conditional probability of death given encounter, and overall wolf and elk resource selection to test whether predation risk is simply equivalent to location of the predator. We then combine the probability of encounter and conditional probability of death into a spatially explicit function of predation risk following Lima and Dill's reformulation of Holling's functional response. We illustrate this approach in a wolf–elk system in and adjacent to Banff National Park, Alberta, Canada. In this system we found that the odds of elk being encountered by wolves was 1.3 times higher in pine forest and 4.1 times less in grasslands than other habitats. The relative odds of being killed in pine forests, given an encounter, increased by 1.2. Other habitats, such as grasslands, afforded elk reduced odds (4.1 times less) of being encountered and subsequently killed (1.4 times less) by wolves. Our approach illustrates that predation risk is not necessarily equivalent to just where predators are found. We show that landscape attributes can render prey more or less susceptible to predation and effects of landscape features can differ between the encounter and attack stages of predation. We conclude by suggesting applications of our approach to model predator–prey dynamics using spatial predation risk functions in theoretical and applied settings.     

External irradiation of the hypophysis for Cushing's disease

During the past 12 years 17 patients with Cushing''s disease (bilateral adrenal hyperplasia secondary to excessive pituitary adrenocorticotrophic hormone) have been treated initially with external pituitary irradiation. Of the 15 patients who have had adequate follow-up, nine showed complete biochemical remission, and one showed biochemical improvement. There were no complications. It is therefore recommended that the first mode of therapy for all patients with Cushing''s disease should be pituitary irradiation if the patient''s clinical condition permits.     

PUBLIC HEALTH REPORT: Increase in Arthropod-Borne Encephalitis a Possibility

THE COMMUNICATION below is the first of what is intended as a continuing series of reports from the State of California Department of Public Health on topics of interest to physicians in private practice. On a number of occasions in the past, Dr. Malcolm H. Merrill, Director of Public Health, has appeared before the Council of the California Medical Association with intensely interesting reports on matters of public health and the attitudes and functions of the department. Since the minutes of the meetings of the Council give only the briefest of notes on such communications, Dr. Merrill was asked—and has agreed—to make use of this section of California Medicine for public health reports that can be informative and useful to all members.     

THE EFFECT OF ENZYME PURITY ON THE KINETICS OF TRYPTIC HYDROLYSIS

The rates of digestion of keratose have been determined with three commercial enzymes, ranging widely in strength. It has been found that the weaker the enzyme preparation, the more nearly does the course of the hydrolysis conform to that of a reaction of the first order. This has been explained on the assumption that in solution an equilibrium exists between active enzyme, and enzyme combined with inert material. In very impure enzyme preparations, the large quantities of combined enzyme act as a reservoir for active enzyme, maintaining a constant concentration of active enzyme during the course of the digestion.