Electrophoretic behavior of the H+-ATPase proteolipid from bovine heart mitochondria

The proteolipid subunit of H⁺-ATPase was labeled by [¹⁴C]N,N-dicyclohexylcarbodiimide in bovine heart mitochondria. The radioactive labeling was followed using various systems of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). When using discontinuous SDS-PAGE (Laemmli, U.K., 1970,Nature (London)227, 680–685) a monomeric (Mr 7600±1500) and a dimeric form (Mr 17,800±1200) of the proteolipid were detected, while only the monomeric form was found on urea (8 M) containing gels (SDS-PAGE according to Laemmli; or Swank, R. T., and Munkers, K. D., 1971,Anal. Biochem. 39, 462–477). When using SDS-PAGE with Na-P_i buffer (Weber, K., and Osborn, M., 1969,J. Biol. Chem. 244, 4406–4442), only a dimeric form of the proteolipid (Mr 15,000±1000) was detected. Experimental data indicate that the different patterns of proteolipid separation are related to the presence of the two distinct proteolipid conformations in the SDS solution.     

Reproductive strategies of the orang-utan: New data and a reconsideration of existing sociosexual models

Recent field data indicate that MacKinnon’s model of the orang-utan’s sexual and agonistic activity needs to be revised. In this model, male reproductive activity is concentrated in an extended phase of subadulthood and in early adulthood. According to this model, the role of older adult males is primarily that of range guardian, and in that role they would ensure that the offspring they had generated earlier would have safe access to food resources. This study presents cases suggesting that subadult males, even though sexually active, may have low reproductive success. In previous studies adult males were shown to display less sexual initiative than subadult males. In this study an adult male was at times involved infrequent mating activity in response to proceptive activity of females in the course of consortship. This adult male proved to be a successful breeder, thus refuting the hypothesis of adult male sterility. The female is most likely to conceive through cooperative mating in lengthy consortships with the dominant resident adult male. We hypothesize that the extended subadult phase represents a submissive strategy, allowing subadult males to remain in the home range of adult males but with minimal reproductive success.     

Fine structure of the malaria parasite Plasmodium falciparum in human hepatocytes in vitro

Summary Recent advances in the ability to culture the hepatic forms of mammalian malaria parasites, particularly of the important human pathogen Plasmodium falciparum have provided novel opportunities to study the ultrastrucural organisation of the parasite in its natural host cell the human hepatocyte. In this electron-microscopic and immunofluorescence study we have found the morphology of both parasite and host cell to be well preserved. The exoerythrocytic forms, which may be found at densities of up to 100/cm², grow at rates comparable to that in vivo in the chimpanzee. In the multiplying 5- and 7-day schizogonic forms the ultrastructural organisation of the parasite bears striking resemblances to other mammalian parasites, e.g., the secretory activity and distribution of the peripheral vacuole system, but also homology with avian parasites, e.g., in nuclear and nucleolar structure and mitochondrial form. The latter homologies support earlier suggestions of the close phylogenetic relationship of P. falciparum with the avian parasites. Evidence is also presented showing the persistence of the cytoskeleton of the invasive sporozoite within the cytoplasm of the ensuing rapidly growing vegetative parasites.     

Protein composition of the carboxysomes of Thiobacillus neapolitanus

For purifying carboxysomes of Thiobacillus neapolitanus an isolation procedure was developed which resulted in carboxysomes free from whole cells, protoplasts and cell fragments. These purified carboxysomes are composed of 8 proteins and at the most of 13 polypeptides. The two most abundant proteins which make up more than 60% of the carboxysomes, are ribulose-1,5-bisphosphate carboxylase and a glycoprotein with a molecular weight of 54,000. The shell of the carboxysomes consists of four glycoproteins, one also with a molecular weight of 54,000. The other proteins are present in minor quantities. Ribulose-1,5-bisphosphate carboxylase is the only enzyme which could be detected in the carboxysomes and 3-phosphoglycerate was the only product formed during incubation with ribulose-1,5-diphosphate and bicarbonate. The supernatant of a broken and centrifuged carboxysome suspension contained the large subunit of ribulose-1,5-bisphosphate carboxylase. The small subunit of ribulose-1,5-bisphosphate carboxylase was found in the pellet together with the shell proteins which indicates that the small subunit of ribulose-1,5-bisphosphate carboxylase is connected to the shell.Abbreviations RuBisCO ribulose-1,5-bisphosphate carboxylase - PMSF phenylmethylsulfonyl fluoride - PAA gelectrophoresis, polyacrylamide gelelectrophoresis - SDS sodium dodecyl sulphate - CIE crossed immunoelectrophoresis - IEF isoelectric focusing     

Monoclonal antibody-defined antigens of human prostate cancer cell line PC3

Summary Over 600 hybridomas were derived from the immunization of mice with live cells and aqueous extracts of the human prostatic carcinoma cell line PC3. A total of 26 hybridomas with restricted reactivities were selected, subcloned and antibodies tested on a variety of tumor and normal cells. Seven monoclonal antibodies showed reactivity for prostate cancer and other tumor cell lines, including breast carcinomas. Three of the antibodies obtained after immunization with live cells reacted with live cells only and three of the four antibodies obtained after immunization with cell extract reacted with cell extracts and spent culture media. The fourth antibody in the latter group was reactive only in the immunoperoxidase staining assay. Antibody PrS5 recognized a 90,000 molecular weight molecule from ¹²⁵I-surface-labeled cells in immunoprecipitation analysis. Antibodies PrE3 and PrD8 detected a nonacid glycolipid pentasaccharide from PC3 cells and meconium, and a glycoprotein of 115,000 molecular weight from ¹²⁵I-surface-labeled red blood cells. The similar patterns of reactivity in RIAs and antigen analysis suggest that antibodies PrE3 and PrD8 recognize the same molecule. The results emphasize the usefulness of immunohistochemistry in the testing of monoclonal antibodies and the impact of the form in which the antigen is presented on the resultant antibody specificity     

Lysis of autologous tumor cells by blood lymphocytes tested at the time of surgery

Summary Lymphocyte-mediated lysis of autologous tumor cells (autologous lymphocyte cytotoxocity ALC) was tested at the time of surgery in 108 patients (46 squamous cell carcinomas of the lung, 25 adenocarcinomas of the lung, 19 soft tissue sarcomas and 18 osteosarcomas). The clinical course of these patients in relation to the test results has been published previously. The group was evaluated again after an extended observation time, now with a mean of 80.2 months (range 36–108). The test was rarely positive in patients with metastasis (2 out of 28 experiments).There was a correlation between the ALC results and the postsurgical clinical course for patients without detectable metastasis in that (1) a negative test was invariably a bad prognostic sign, i.e., all 32 patients with negative ALC died within 3 years (mean survival time 16.1 months). (2) The remission and survival times were longer for the ALC positive patients (p<0.001). (3) All 37 individuals who are alive at present without recurrence belong to the reactive group.The ALC results correlated with the clinical course in 88% of patients. The correlation was highest for the groups of soft tissue sarcoma and adenocarcinoma of the lung. There was no correlation between killing of K562 cells and ALC, or between lymphoproliferative response to PHA and ALC reactivity.     

Major differences between glutamate-fermenting species isolated from chemostat enrichments at different dilution rates

Abstract From chemostat enrichments conducted at dilution rates of 0.025, 0.12 and 0.25 h⁻¹ glutamate- and aspartate-fermenting bacteria were isolated. The dominant aspartate-fermenting strains in all these enrichments belonged to the genus Campylobacter , whereas 3 dissimilar types of glutamate-fermenting bacteria predominated at the different dilution rates. One of these strains was identified as Clostridium cochlearium . The remaining two were designated as strain DKglu16 (glutamate → acetate + propionate + ammonium + carbon dioxide) and DKglu21 (glutamate → acetate + formate + ammonium + carbon dioxide). Grown in continuous culture under glutamate limitation, strain DKglu16 (μ_max= 0.13 h⁻¹; K _s= 1.9 μM) outcompeted C. cochlearium (μ_max= 0.36 h⁻¹; K _s= 7 μM) at low dilution rates, but was outgrown at higher rates of dilution (0.044 h⁻¹). In glutamate-limited continuous culture the competitiveness of strain DKglu16 increased considerably when lactate was added to the feed in addition to glutamate.     

Proteins of the Bacillus stearothermophilus ribosome: Crystallization of protein L6

Crystals of ribosomal protein L6 from Bacillus stearothermophilus suitable for high resolution structural studies have been obtained. Crystals are hexagonal with space group P6₁22 (or the enantiomorph P6₅22) and cell dimensions a = b = 72.7 Å, c = 124.9 Å. A search for heavy atom derivatives is in progress.     

The bulk rheology of close-packed red blood cells in shear flow

A theoretical analysis is made of the dynamical behavior and bulk rheology of close-packed red blood cell suspensions subjected to simple shear flow. The model for the polyhedral cell shapes and tank-treading membrane motion developed in the companion paper (1) is used. The flow in the thin lubricating plasma layers between cells is analyzed taking into account the mechanical properties of the membrane at the corner regions of sharp membrane curvature. This leads to predictions for the apparent viscosity as a function of hematocrit and shear rate. Good agreement with experimental results is obtained at moderate and high shear rates (above 20 s-1). At lower shear rates, a rapid rise in apparent viscosity has been found experimentally, and the mechanisms leading to this behavior are examined.