Proteolytic activity within lysosomes and turnover of pinocytic vesicles a kinetic analysis

In previous studies, in vitro digestion of [^{1 2 5}I] ribonuclease by lysosomes of mouse kidney was limited because breakdown, which was rapid at first slowed markedly so that most of the labeled protein escaped degradation. We now describe incubation conditions which allow digestion to proceed until approximately 70% of the exogenous protein label is released in acid-soluble from, after 30–45 min at 37°C. Such activity is seen with either the addition of EDTA or incubation of concentrated cell particle suspensions. EDTA is effective in low concentrations and shows the same stimulation of digestion over a range of approximately 10⁻⁶−10⁻³ M. Other chelating agents have similar effects; dipyridyl and hydroxquinoline are as effective as EDTA, o-phenanthroline and diethyldithiocarbamate are slightly less effective. When the incubation medium had been treated with a chelating resin, Chelex 100, dilute suspensions of lysosomes were as active as those in EDTA. These results lead to the conclusion that metal ions, present as contaminants in very small concentraions, inhibit the activity of mouse kidney lysosomes.The effect of the metal ions is to diminish lysosomal stability, leading to release of intact labeled ribonuclease in non-sedimentable form. Interaction between lysosomes and metal, leading to inhibition of digestion upon heating occurs at low temperature, but breakdown requires incubation at 37°C and may be autolytic. In contrast to chelators, mercaptoethanol is without marked effect on stability; the stimulation in digestion rate caused by this agent is due either to a direct effect on the lysosomal enzymes or to a non-destructive influence on the lysosomal structure.     

The application of biomechanical motion analysis to aspects of green monkey (Cercopithecus a. sabaeus) locomotion

A cinematographic method of biomechanical motion analysis is presented which permits the determination of body segment forces and joint moments of force, and thereby dominant muscle action. An analysis of the horizontal leap of Cercopithecus is used as an example of the utility of this approach in the area of functional morphology. Kinematic and kinetic data are presented and discussed in terms of the biomechanical requirements of this form of locomotion. The importance of a consideration of inertial as well as gravitational forces in an analysis of positional behavior involving body motion is stressed.     

The dermatoglyphics of American Negroes

Digital and palmar dermatoglyphics of 184 male and 224 female normal American Negroes were evaluated for digital patterns, digital ridge counts, palmar patterns, palmar main line terminations, accessory triradii and palmar creases. All subjects were seven year olds examined and found free of chronic or other genetic diseases. The results were presented for the left and right hand for the most part comparable to those of the African and other American Negro groups reported earlier. The distributions of the various dermatoglyphic features among the Negroes taken as a group were compared to those of the other racial groups and their differences were discussed.     

Winter locations of red‐throated divers from geolocation and feather isotope signatures

Migratory species have geographically separate distributions during their annual cycle, and these areas can vary between populations and individuals. This can lead to differential stress levels being experienced across a species range. Gathering information on the areas used during the annual cycle of red‐throated divers (RTDs; Gavia stellata) has become an increasingly pressing issue, as they are a species of concern when considering the effects of disturbance from offshore wind farms and the associated ship traffic. Here, we use light‐based geolocator tags, deployed during the summer breeding season, to determine the non‐breeding winter location of RTDs from breeding locations in Scotland, Finland, and Iceland. We also use δ¹⁵N and δ¹³C isotope signatures, from feather samples, to link population‐level differences in areas used in the molt period to population‐level differences in isotope signatures. We found from geolocator data that RTDs from the three different breeding locations did not overlap in their winter distributions. Differences in isotope signatures suggested this spatial separation was also evident in the molting period, when geolocation data were unavailable. We also found that of the three populations, RTDs breeding in Iceland moved the shortest distance from their breeding grounds to their wintering grounds. In contrast, RTDs breeding in Finland moved the furthest, with a westward migration from the Baltic into the southern North Sea. Overall, these results suggest that RTDs breeding in Finland are likely to encounter anthropogenic activity during the winter period, where they currently overlap with areas of future planned developments. Icelandic and Scottish birds are less likely to be affected, due to less ship activity and few or no offshore wind farms in their wintering distributions. We also demonstrate that separating the three populations isotopically is possible and suggest further work to allocate breeding individuals to wintering areas based solely on feather samples.     

Inference of Gene Flow between Species under Misspecified Models

Genomic sequence data provide a rich source of information about the history of species divergence and interspecific hybridization or introgression. Despite recent advances in genomics and statistical methods, it remains challenging to infer gene flow, and as a result, one may have to estimate introgression rates and times under misspecified models. Here we use mathematical analysis and computer simulation to examine estimation bias and issues of interpretation when the model of gene flow is misspecified in analysis of genomic datasets, for example, if introgression is assigned to the wrong lineages. In the case of two species, we establish a correspondence between the migration rate in the continuous migration model and the introgression probability in the introgression model. When gene flow occurs continuously through time but in the analysis is assumed to occur at a fixed time point, common evolutionary parameters such as species divergence times are surprisingly well estimated. However, the time of introgression tends to be estimated towards the recent end of the period of continuous gene flow. When introgression events are assigned incorrectly to the parental or daughter lineages, introgression times tend to collapse onto species divergence times, with introgression probabilities underestimated. Overall, our analyses suggest that the simple introgression model is useful for extracting information concerning between-specific gene flow and divergence even when the model may be misspecified. However, for reliable inference of gene flow it is important to include multiple samples per species, in particular, from hybridizing species.