Plasma membrane of a murine T cell lymphoma: surface labelling, membrane isolation, separation of membrane proteins and distribution of surface label amongst these proteins.

Two established techniques for analysis of plasma membranes, namely, lactoperoxidase catalyzed surface radioiodination of intact cells and bulk membrane isolation following disruption of cells by shear forces, were applied in studies of membrane proteins of continuously cultured cells of the monoclonal T lymphoma line WEHI-22. It was found that macromolecular 125I-iodide incorporated into plasma membrane proteins of intact cells was at least as good a marker for the plasma as was the commonly used enzyme 5'-nucleotidase. T lymphoma plasma membrane proteins were complex when analysed by polyacrylamide gel electrophoresis in sodium dodecylsulphate-containing buffers and more than thirty distinct components were resolved. More than fifteen of the components observed on a mass basis were also labelled with 125I-iodide. Certain bands, however, exhibited a degree of label disproportionate to their staining properties with Coomassie Blue. This was interpreted in terms of their accessibility to the solvent in the intact cells.     

Human chromosomes. Evidence for autosomal sexual dimorphism.

The karyotypes of 100 males and 100 females, each assembled by the trypsin banding method, are examined in a study designed to investigate sex differences among autosomes. It is shown that female autosomes are consistently longer than those of the males, with respect to both the short and long arm measurements. In addition, discriminant analysis is used to distinguish between the male and female karyotypes. We find that, using autosomal measurements alone, this can be done with a high probability of success.     

Iodination of glyceraldehyde 3-phosphate dehydrogenase from Bacillus stearothermophilus.

The reaction of iodine with glyceraldehyde 3-phosphate dehydrogenase from Bacillus stearothermophilus was investigated. The active-site thiol group of the cysteine residue homologous with cysteine-149 in the pig muscle enzyme was protected by reaction with tetrathionate. The apoenzyme was readily inhibited by KI3 solution at pH8, but the coenzyme, NAD+, protected the enzyme against inhibition and decreased the extent of iodination. At pH 9.5, ready inhibition of both apo- and holo-enzyme was observed. Tryptic peptides containing residues iodinated at pH 8 were isolated and characterized. One of the most reactive residues in both holo- and apo-enzymes was a tyrosine homologous with tyrosine-46 in the pig muscle enzyme, and this residue was iodinated without loss of enzymic activity. Other reactive tyrosine residues in the apoenzyme were in positions homologous with residues 178, 273, 283 and 311 in the pig muscle enzyme, but they were not readily iodinated in the holoenzyme. Histidine residues in both holo- and apo-enzymes were iodinated at pH 8 in sequence positions homologous with residues 50, 162 and 190 in the pig muscle enzyme. The inhibition of the enzyme was not correlated with the iodination of a particular residue. The results are discussed in relation to a three-dimensional model based on the structure of the lobster muscle enzyme and demonstrate that conformational changes affecting the reactivity of several tyrosine residues most probably occur on binding of the coenzyme.     

Demographic responses to climate‐driven variation in habitat quality across the annual cycle of a migratory bird species

The demography and dynamics of migratory bird populations depend on patterns of movement and habitat quality across the annual cycle. We leveraged archival GPS‐tagging data, climate data, remote‐sensed vegetation data, and bird‐banding data to better understand the dynamics of black‐headed grosbeak (Pheucticus melanocephalus) populations in two breeding regions, the coast and Central Valley of California (Coastal California) and the Sierra Nevada mountain range (Sierra Nevada), over 28 years (1992–2019). Drought conditions across the annual cycle and rainfall timing on the molting grounds influenced seasonal habitat characteristics, including vegetation greenness and phenology (maturity dates). We developed a novel integrated population model with population state informed by adult capture data, recruitment rates informed by age‐specific capture data and climate covariates, and survival rates informed by adult capture–mark–recapture data and climate covariates. Population size was relatively variable among years for Coastal California, where numbers of recruits and survivors were positively correlated, and years of population increase were largely driven by recruitment. In the Sierra Nevada, population size was more consistent and showed stronger evidence of population regulation (numbers of recruits and survivors negatively correlated). Neither region showed evidence of long‐term population trend. We found only weak support for most climate–demographic rate relationships. However, recruitment rates for the Coastal California region were higher when rainfall was relatively early on the molting grounds and when wintering grounds were relatively cool and wet. We suggest that our approach of integrating movement, climate, and demographic data within a novel modeling framework can provide a useful method for better understanding the dynamics of broadly distributed migratory species.     

Simple isolation of functional RNA from woody stems of gymnosperms

Stems of woody conifers contain high levels of polysaccharides and phenolic compounds that complicate the isolation of functional RNA from this highly lignified tissue. These difficulties were overcome by pulverizing the frozen tissue with a stainless-steel mortar and by effectively sequestering interfering phenolic compounds with vinylpyrrolidone polymers, thereby minimizing damage to nucleic acids during extraction. RNases were inhibited by aurintricarboxylic acid, and gelatinous polysaccharides were removed by inclusion of a 10% ethanol precipitation step. RNA was then isolated by precipitation with 33% isopropanol and ultracentrifugation onto a cushion of 5.7 M CsCl. Yields of 10 to 20 μg RNA/g FW were obtained from woody stems of several different gymnosperm species, including grand fir (Abies grandis), lodgepole pine (Pinus contorta), loblolly pine (Pinus taeda), Douglas fir (Pseudotsuga menziesii) and Pacific yew (Taxus brevifolia). The high quality of the RNA obtained was determined by UV-spectrophotometry, denaturing agarose gel electrophoresis, andin-vitro translation, and this material was used to construct cDNA libraries.     

Premature mitosis induced in mammalian cells by the protein kinase inhibitors 2-aminopurine and 6-dimethylaminopurine.

The protein kinase inhibitors 2-aminopurine (2-AP) and 6-dimethylaminopurine (6-DMAP) were used to examine the effects of protein dephosphorylation on the control of mitosis in mammalian cells. Both 2-AP and 6-DMAP induced premature mitosis in hamster fibroblasts that were arrested in S phase. This response was characterized by changes in cell morphology, breakdown of the nuclear envelope, and premature chromosome condensation. Premature mitosis was followed by a return to interphase morphology and reformation of the nuclear envelope around decondensed and fragmented chromatin to form numerous micronuclei. The activity of both compounds was dependent upon new protein synthesis but not new RNA synthesis. 2-AP and 6-DMAP acted cooperatively with each other and with caffeine, suggesting a common mechanism of action. In exponentially growing cells, 2-AP and 6-DMAP did not induce premature mitosis but did increase the frequency of binucleated cells by blocking cytokinesis. These findings support a role for protein dephosphorylation in the control of mitosis and indicate that cell cycle perturbations can modify this regulation.     

The Roles of Sex,Mass and Individual Specialisation in Partitioning Foraging-Depth Niches of a Pursuit-Diving Predator

Intra-specific foraging niche partitioning can arise due to gender differences or individual specialisation in behaviour or prey selection. These may in turn be related to sexual size dimorphism or individual variation in body size through allometry. These variables are often inter-related and challenging to separate statistically. We present a case study in which the effects of sex, body mass and individual specialisation on the dive depths of the South Georgia shag on Bird Island, South Georgia are investigated simultaneously using a linear mixed model. The nested random effects of trip within individual explained a highly significant amount of the variance. The effects of sex and body mass were both significant independently but could not be separated statistically owing to them being strongly interrelated. Variance components analysis revealed that 45.5% of the variation occurred among individuals, 22.6% among trips and 31.8% among Dives, while R² approximations showed gender explained 31.4% and body mass 55.9% of the variation among individuals. Male dive depths were more variable than those of females at the levels of individual, trip and dive. The effect of body mass on individual dive depths was only marginally significant within sexes. The percentage of individual variation in dive depths explained by mass was trivial in males (0.8%) but substantial in females (24.1%), suggesting that differences in dive depths among males was largely due to them adopting different behavioural strategies whereas in females allometry played an additional role. Niche partitioning in the study population therefore appears to be achieved through the interactive effects of individual specialisation and gender upon vertical foraging patch selection, and has the potential to interact in complex ways with other axes of the niche hypervolume such as foraging locations, timing of foraging and diet.     

An integrative taxonomic revision of the Cape Verdean skinks (Squamata,Scincidae)

Miralles, A., Vasconcelos, R., Perera, A., Harris, D. J. & Carranza, S. (2010). An integrative taxonomic revision of the Cape Verdean skinks (Squamata, Scincidae). —Zoologica Scripta, 40, 16–44. A comprehensive taxonomic revision of the Cape Verdean skinks is proposed based on an integrative approach combining (i) a phylogenetic study pooling all the previously published molecular data, (ii) new population genetic analyses using mitochondrial and nuclear data resulting from additional sampling, together with (iii) a morphological study based on an extensive examination of the scalation and colour patterns of 516 live and museum specimens, including most of the types. All Cape Verdean species of skinks presently recognised, formerly regarded as members of the genera Mabuya Fitzinger, 1826 and Macroscincus Bocage, 1873 are considered as members of the Cape Verdean endemic genus Chioninia Gray, 1845. The new phylogeny and networks obtained are congruent with the previously published phylogenetic studies, although suggesting older colonization events (between 11.6 and 0.8 Myr old), and indicate the need for taxonomic changes. Intraspecific diversity has been analysed and points to a very recent expansion of Chioninia delalandii on the southern islands and its introduction on Maio, to a close connection between Chioninia stangeri island populations due to Pleistocene sea‐level falls and to a generally low haplotypic diversity due to the ecological and geological characteristics of the archipelago. Three new consistent morphological synapomorphies supporting two of the four main clades of the genus have been identified. The complex taxonomic status of Euprepes fogoensis O’Shaughnessy, 1874 has been resolved and a lectotype has been designated for this species; Chioninia fogoensis nicolauensis (Schleich, 1987) is elevated to species rank, whereas Chioninia fogoensis antaoensis (Schleich, 1987) is now regarded as a junior subjective synonym of C. fogoensis. Additionally, one new subspecies of Chioninia vaillanti and two of Chioninia spinalis are described (Chioninia vaillanti xanthotis ssp. n., Chioninia spinalis santiagoensis ssp. n. and Chioninia spinalis boavistensis ssp. n.) and a lectotype has been designated for Mabuia spinalis Boulenger, 1906. Finally, an identification key for the Chioninia species is presented.