The induction of allophanate lyase during the vegetative cell cycle in light-synchronized cultures of Chlamydomonas reinhardi.

Allophanate lyase can be induced by urea or acetamide 20-40-fold within 4 h in NH4 + -deprived cultures of Chlamydomonas reinhardi. In light-synchronized cultures, allophanate lyase induction appeared to be limited to the light phase of the cell cycle, provided that culture samples were induced under ongoing illumination conditions (i.e. light induction of light phase cells and dark induction of dark phase cells). However, when culture samples were induced under constant light conditions this cell cycle pattern was abolished. Light was found to be required for allophanate lyase induction and this was shown to be due, in part, to the light requirement for inducer uptake. The relationship between allophanate lyase induction and gametogenesis is discussed.     

Seasonal organization of breeding and molting in the Fiscal Shrike (Lanius collaris)

Summary Free-living Fiscal Shrikes were investigated in Nakuru Kenya for seasonal patterns in breeding, gonadal size, molt and the plasma titers of LH, T in males and E 2 in females. Both breeding and molt were found to be seasonally restricted activities. A complete molt occurred from August to December after breeding had ceased. Although the gonads in some birds were well developed during the dry season, at the beginning of the year, no breeding was found until the onset of the heavy rains. It is proposed that severe drought inhibits reproductive activity and correspondingly the secretion of gonadal steroids (T and E 2) in Fiscal Shrikes without affecting increases in gonadal size.

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Brut- und Mauserzeiten beim Fiskalwürger (Lanius collaris)

Zusammenfassung Der Fiskalwürger ist die häufigste afrikanische Würgerart. Er ernährt sich von Insekten, Reptilien, kleinen Säugetieren und Vögeln. VonBrown &Britton (1980) undMacDonald (1980) wurde wegen dieser Beutevielfalt vermutet, daß er auch unter ungünstigen Umweltbedingungen (Trockenheit) brüten kann. In Nakuru, Kenya, wurde untersucht, ob jahreszeitlich bedingte Unterschiede in Brutaktivität, Gonadengröße, Mauser und in Plasmatitern von LH, T und E 2 vorhanden waren. Brutaktivität und Mauser waren mit der Hauptregenzeit korreliert. Die Brutzeit endete mit Beginn der Mauser, die von August bis Dezember dauerte. Obwohl die Gonaden bei einigen Vögeln schon während der Trockenzeit (Januar bis März) gut entwickelt waren, gab es bis zur Regenzeit keinen Hinweis auf Fortpflanzungsaktivität. Es wird angenommen, daß eine strenge Trockenzeit die Ausschüttung von Testosteron () und Estradiol () verhindert, ohne die Gonadengröße zu beeinflussen. In Gegensatz zu den vorher genannten Autoren wurde keine Fortpflanzungsaktivität in Trockenzeiten festgestellt. Das beruht vielleicht auf dem in einzelnen Jahren unterschiedlichen Ausmaß der Trockenzeit.

     

Substrate stabilization of the palmitoyl-coenzyme A hydrolase activity of rat submaxillary gland.

The long-chain acyl-CoA hydrolase (EC 3.1.2.2) activity of rat submaxillary salivary gland, found in the postmicrosomal supernatant fraction, has a pH optimum of 7.4. This hydrolase activity was found to be extremely labile, but inclusion of glycerol or the substrate palmitoyl-CoA in the preparations markedly stabilized the activity. Gel-filtration studies revealed multiple forms of the hydrolase, a lower-molecular-weight species of approx. 45 000 and a higher-molecular-weight species of approx. 130 000 observed when glycerol (20%, v/v) or palmitoyl-CoA (10 micro M) were included in the eluting buffer. This phenomenon is similar to that observed with the palmitoyl-CoA hydrolase of rat brain, except that there is no evidence that the higher-molecular-weight species of the hydrolase of submaxillary gland is generated by substrate-induced dimerization of the lower-molecular-weight species.     

Beitrag zur Standortcharakteristik verschiedener Grünland-Pflanzengesellschaften

Zusammenfassung Die Standortcharakteristik verschiedener Grünlandpflanzengesellschaften hat nicht nur für die Grünlandbewirtschaftung große Bedeutung, sondern auch für die Kennzeichnung einzelner Pflanzengesellschaften und für die Ermittlung qualitativer oder auch quantitativer Zeigereigenschaften. Am Untersuchungsmaterial von mehr als 400 untersuchten Grünlandpflanzenbeständen wird gezeigt, daß einzelne Analysenwerte, also Momentaufnahmen ebenso wie die aus einer größeren Zahl von Einzelwerten gebildeten Mittelwerte nur groben Orientierungscharakter besitzen. Daran ändert sich auch durch die Prüfung eines umfangreicheren Analysenmaterials mittels Regressionsanalyse nicht viel.Zeitreihenanalysen, wie sie auf 5 Standorten in zwei Vegetationsperioden durchgeführt wurden, geben einen Einblick in die Dynamik der Meßgrößen. Durch die Anwendung moderner Rechenverfahren konnten sowohl einfache, wie multiple Zusammenhänge verschiedener Standortsfaktoren geprüft werden. Dabei ist zu erkennen, daß die Unterschiede zwischen verschiedenen Pflanzengesellschaften durchweg kleiner sind als die Unterschiede zwischen verschiedenen Jahren. Trotz der teilweise nur sehr geringen Bestimmtheitsmaße ermöglichen die Untersuchungen einen Einblick in das Geschehen am natürlichen Standort und bilden die Basis für weitergehende experimentelle Untersuchungen. Auf die für die Grünlandwirtschaft bedeutenden Zusammenhänge zwischen verschiedenen Standortsfaktoren und der Ertragsbildung der Pflanzenbestände wird hingewiesen.

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Summary The local characterization of different grassland-associations is not only of great significance for the grassland-farming but even to mark special plant-associations and for the determination of possibilities for qualitative and quantitative diagnosis by plants. It is shown by 400 determined locations of permanent grassland that some special analysis taken at a fixed time (moment-pictures) as well as the average values calculated from a great many of single analysis can give only an unexact orientation. The testing of this comprehensive material by regression-analysis brought no better results.Series of analysis carried out during growth on 5 locations in 2 vegetation periods give an impression of the dynamik of the growth-factors.There could be tested simple correlations between locations factors as well as multiple ones by modern mathematic methods. Thereby has been found mostly a smaller distinction between the different plant associations than between the different years. Although the found coefficients of determination are very small, the determinations give an interesting impression of what happens on a natural location and they are a good basis for further experiments. Pointing to the relations between the different location factors and the grass growth of the sward a report is given of the great significance for the grassland farming.

     

Relationship between epidermal growth factor receptor occupancy and mitogenic response. Quantitative analysis using a steady state model system

Because mitogenic stimulation by epidermal growth factor (EGF) requires at least an 8--12-h exposure to commit the majority of the cells to divide, a number of complicating processes must be evaluated in an analysis of the relationship between receptor occupancy and the biological response. During this period, the number of cellular EGF receptors changes and the cells continuously bind, internalize, and degrade the hormone. To deal with these changes, we utilized our previously described steady state model that permits an analysis of EGF interactions with cells under steady state conditions. For these studies we derived and measured a number of steady state rate constants to describe the interaction of 125I-EGF with cultured human and mouse fibroblast-like cells. The validity of these constants was established by demonstrating the close agreement between experimentally determined results and predicted results from computer simulations using these constants. These approaches in conjunction with experiments on the mitogenic stimulation of the cells with EGF led to the conclusion that there is a linear relationship between mitogenic stimulation and EGF receptor occupancy at steady state, with no apparent "spare" EGF receptors.     

Bleeding After Liver Biopsy

During nine years 3,080 liver biopsies were carried out and bleeding occurred in 22 of the patients (0.7 percent). Transfusions were given to 17 of these patients and laparotomies were done to control the bleeding in six. All survived. Bleeding was evident within three hours in 19 patients, but occurred from 3 to 13 days after biopsy in the remaining three. Pain requiring analgesic medication and a fall in blood pressure were the usual indications that major bleeding had occurred. Relative contraindications to biopsy (particularly a prolonged prothrombin time) were present in 10 of the 22 bleeding patients and in only 2 of the 41 nonbleeding controls (P<0.001). We believe that some of the bleeding episodes could have been prevented with more careful attention to the indications and contraindications to biopsy, and more rigorous correction of recognized clotting abnormalities.     

Evaluating the necessity of additional aquatic plant testing by comparing the sensitivities of different species

At present, at least three and up to five plant species are required to assess the potential risks of herbicides to non-target aquatic plants. Several regulatory authorities are considering whether there should be further requirements based on concerns about the possible selectivity of herbicides (e.g., specific modes of action against dicotyledonous plants). The relative sensitivity of a range of aquatic plants is assessed in our work in order to evaluate the implications of differences in species sensitivity for aquatic risk assessment of herbicides. We therefore present results from ecotoxicological tests performed at Syngenta Crop Protection AG on various aquatic plants and compare them to available studies and results in literature. The criterion used for sensitivity ranking is the EC50 (median effect concentration) value, which allows a better comparison of values from different testing methods and conditions. The overall results obtained in the present work show that the aquatic risk assessment procedure for herbicides based on Lemna sp. and algae is sufficiently protective while identifying potential toxicity to non-target plants. Only few exceptions concerning herbicides with selective modes of action (e.g., auxin simulators) may require additional species testing for proper risk assessment.     

Young patients with colorectal cancer have poor survival in the first twenty months after operation and predictable survival in the medium and long-term: Analysis of survival and prognostic markers

Introduction

Male breast cancer (MBC) is a rare, yet potentially aggressive disease. Although literature regarding female breast cancer (FBC) is extensive, little is known about the etiopathogenesis of male breast cancer. Studies from our laboratory show that MBCs have a distinct immunophenotypic profile, suggesting that the etiopathogenesis of MBC is different from FBCs. The aim of this study was to evaluate and correlate the immunohistochemical expression of cell cycle proteins in male breast carcinoma to significant clinico-biological endpoints.

Methods

75 cases of MBC were identified using the records of the Saskatchewan Cancer Agency over 26 years (1970-1996). Cases were reviewed and analyzed for the immunohistochemical expression of PCNA, Ki67, p27, p16, p57, p21, cyclin-D1 and c-myc and correlated to clinico-biological endpoints of tumor size, node status, stage of the disease, and disease free survival (DFS).

Results

Decreased DFS was observed in the majority of tumors that overexpressed PCNA (98%, p = 0.004). The overexpression of PCNA was inversely correlated to the expression of Ki67 which was predominantly negative (78.3%). Cyclin D1 was overexpressed in 83.7% of cases. Cyclin D1 positive tumors were smaller than 2 cm (55.6%, p = 0.005), had a low incidence of lymph node metastasis (38.2%, p = 0.04) and were associated with increased DFS of >150 months (p = 0.04). Overexpression of c-myc (90%) was linked with a higher incidence of node negativity (58.3%, p = 0.006) and increased DFS (p = 0.04). p27 over expression was associated with decreased lymph node metastasis (p = 0.04). P21 and p57 positive tumors were related to decreased DFS (p = 0.04). Though p16 was overexpressed in 76.6%, this did not reach statistical significance with DFS (p = 0.06) or nodal status (p = 0.07).

Conclusion

Aberrant cell cycle protein expression supports our view that these are important pathways involved in the etiopathogenesis of MBC. Tumors with overexpression of Cyclin D1 and c-myc had better outcomes, in contrast to tumors with overexpression of p21, p57, and PCNA with significantly worse outcomes. P27 appears to be a predictive marker for lymph nodal status. Such observation strongly suggests that dysregulation of cell cycle proteins may play a unique role in the initiation and progression of disease in male breast cancer. Such findings open up new avenues for the treatment of MBC as a suitable candidate for novel CDK-based anticancer therapies in the future.     

Carbohydrate deficient glycoprotein syndrome type IV: deficiency of dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase

Type IV of the carbohydrate deficient glycoprotein syndromes (CDGS) is characterized by microcephaly, severe epilepsy, minimal psychomotor development and partial deficiency of sialic acids in serum glycoproteins. Here we show that the molecular defect in the index patient is a missense mutation in the gene encoding the mannosyltransferase that transfers mannose from dolichyl-phosphate mannose on to the lipid-linked oligosaccharide (LLO) intermediate Man(5)GlcNAc(2)-PP-dolichol. The defect results in the accumulation of the LLO intermediate and, due to its leaky nature, a residual formation of full-length LLOs. N-glycosylation is abnormal because of the transfer of truncated oligosaccharides in addition to that of full-length oligosaccharides and because of the incomplete utilization of N-glycosylation sites. The mannosyltransferase is the structural and functional orthologue of the Saccharomyces cerevisiae ALG3 gene.     

Finding the Missing Link between Landscape Structure and Population Dynamics: A Spatially Explicit Perspective

We construct and explore a general modeling framework that allows for a systematic investigation of the impact of changes in landscape structure on population dynamics. The essential parts of the framework are a landscape generator with independent control over landscape composition and physiognomy, an individual-based spatially explicit population model that simulates population dynamics within heterogeneous landscapes, and scale-dependent landscape indices that depict the essential aspects of landscape that interact with dispersal and demographic processes. Landscape maps are represented by a grid of 50x50 cells and consist of good-quality, poor-quality, or uninhabitable matrix habitat cells. The population model was shaped in accordance to the biology of European brown bears (Ursus arctos), and demographic parameters were adjusted to yield a source-sink configuration. Results obtained with the spatially explicit model do not confirm results of earlier nonspatial source-sink models where addition of sink habitat resulted in a decrease of total population size because of dilution of high-quality habitat. Our landscape indices, which describe scale-dependent correlation between and within habitat types, were able to explain variations in variables of population dynamics (mean number of females with sink home ranges, mean number of females with source home ranges, and mean dispersal distance) caused by different landscape structure. When landscape structure changed, changes in these variables generally followed the corresponding change of an appropriate landscape index in a linear way. Our general approach incorporates source-sink dynamics as well as metapopulation dynamics, and the population model can easily be modified for other species groups.