Accuracy and repeatability of moose (<Emphasis Type="Italic">Alces alces</Emphasis>) age as estimated from dental cement layers

Optimal research and management of species with age structure often depends on estimates of age-specific population parameters, which in turn depends on reliable methods for age determination. By counting annuli in the cementum of incisor root tips from 51 known-age moose (Alces alces) between 1 and 12 years old, we examined the variation in accuracy and repeatability of age estimates provided by three research technicians with different experiences of aging moose. The most experienced technician estimated the moose age correctly in up to 90% of the cases, while the technician with no prior experience estimated age correctly in up to 73% of the cases. The medium-experienced technician achieved a lower accuracy (up to 53%), indicating that experience alone is not sufficient if the basic training or lack of routine checks against other colleagues or a known-age material are not undertaken. The percentage moose aged within ±1 year from correct age was significantly higher in all technicians (94–98%). After the generally high accuracy, we also found high repeatability (0.980–0.994) within technicians. We conclude that this method of age-determination provides reliable estimates that can be used by management and research to gain information about age-specific patterns in moose populations. However, to obtain estimates of high accuracy the technicians should be well trained, have gained the necessary experience, and most preferably, have access to a sample of teeth from known-age moose.     

The murine receptor for urokinase-type plasminogen activator is primarily expressed in tissues actively undergoing remodeling.

uPAR is a cellular receptor for urokinase plasminogen activator, an enzyme involved in extracellular matrix degradation during processes involving tissue remodeling. We have expressed a recombinant soluble form of murine uPAR and raised rabbit polyclonal antibodies to study the expression of uPAR by immunohistochemistry. The immunohistochemical localization of uPAR was determined in normal mouse organs and in tumors formed by the highly metastatic Lewis lung carcinoma. uPAR immunoreactivity was found in the lungs, kidneys, and spleen, and in endothelial cells in the uterus, urinary bladder, thymus, heart, liver, and testis. No uPAR immunoreactivity was detected in muscle. In general, strong uPAR immunoreactivity was observed in organs undergoing extensive tissue remodeling, as exemplified by trophoblast cells in placenta, and in migrating, but not resting, keratinocytes at the edge of incisional wounds. Staining was not detected in any tissue sections derived from uPAR-deficient mice, thus confirming the specificity of the immunohistochemical staining of uPAR in normal mouse tissues. In Lewis lung carcinoma, uPAR immunoreactivity was found in the tumor cells of the primary tumor and in lung metastases. (J Histochem Cytochem 49:237-246, 2001)     

A DEVELOPMENTAL STUDY OF THE LEAVES OF NICOTIANA GLUTINOSA AS RELATED TO THEIR SMOG–SENSITIVITY

Glater , Ruth Bobrov , Richard A. Solberg , and Flora M. Scott . (U. California, Los Angeles, and Los Angeles County Air Pollution Control District.) A developmental study of the leaves of Nicotiana glutinosa as related to their smog-sensitivity. Amer. Jour. Bot. 49(9): 954–970. Illus. 1962.—Plants growing in the fields of Los Angeles County as well as those experimentally fumigated in the laboratory show gross markings in response to smog which vary from species to species, from a glistening appearance of the leaf undersurface due to a temporary accumulation of water in the affected cells through complete necrosis. In dicotyledonous leaves, “silvering,” “bronzing,” brown-black mottling or an increase in anthocyanin may be seen. In monocotyledons, transverse banding, tan in color, or longitudinal streaking of leaves are the usual responses. This damage appears in a characteristic pattern on the leaves, different from that produced by other phytotoxicants. Nicotiana glutinosa plants were grown in the air-filtered greenhouses at UCLA. The normal anatomical development of the foliage was studied and correlated with its susceptibility to smog injury. On a given plant, leaves of different ages show damage in different positions. Very young leaves at the apex of the plant and old leaves at the base of the plant are not sensitive. Expanding leaves between young and old in age are sensitive; in this group a distinct pattern of damage is discernible. Damage markings in the youngest leaves appear only at the tip; in leaves somewhat older, close to midblade; in fully mature leaves, only at the base. This localization of damage is shown to be correlated with the gradient of cellular differentiation from tip toward base as the leaf matures. Those cells which have just attained maximum size (young mature) are sensitive; damage, therefore, is a function of cellular development and maturity. The following anatomical details were analyzed: (1) differentiation and distribution of stomata and their opening and closing on both upper and lower epidermal surfaces and (2) development of intercellular air spaces in palisade and spongy parenchyma tissue. These studies indicate that damage occurs in the region of the leaf where stomata have just become functional and ambient polluted air can make direct contact with interior leaf tissues by virtue of large substomatal chambers and intercellular air spaces.     

Global solar radiation as the factor controlling induction of diapause in the pod midge (Dasyneura brassicae Winn.)

In this paper we examine the hypothesis that diapause induction in the polyvoltine pod midge Dasyneura brassicae Winn. (Diptera: Cecidomyiidae) is controlled by cumulative global solar radiation during the larval stage. The correlation between field observations of relative diapause for 3 years and four environmental factors (daylength, temperature, cumulative daylight time, and cumulative global solar radiation) was investigated. The cumulative global solar radiation during the larval stage clearly showed the strongest correlation with the observed relative diapause. It was estimated that larvae which cumulated less than 71.1 kWh m⁻² entered diapause. Compared to former theories on diapause induction in insects, this hypothesis explains how temperature and light can function together and, furthermore, it removes the requirement for biological clock involvement in diapause induction in insects. Received: 21 December 1996 / Accepted: 26 February 1997