Wahrnehmungspsychologische Untersuchungen am Eichelhäher. I.

Ohne Zusammenfassung     

Eine Bienendressur auf Wasser

Zusammenfassung Bienen, die mit Zuckerwasser gefüttert werden, das sie durch Drahtgaze aus einer größeren offenen Schale saugen, sind nach wenigen Stunden auf Wasser dressiert. Sie befliegen unter Drahtgaze aufgestellte Glasnäpfchen, die geringe Mengen destilliertes Wasser, Salzwasser, Zitronensaft, Milch oder feuchte Erde enthalten, während sie die gleichen Näpfchen, leer oder mit Alkohol oder Glyzerin beschickt, nicht befliegen.     

Identification of proteins binding the native tubulin dimer

Microtubules play an essential role in eukaryotic cells, where they perform a wide variety of functions. In this paper, we describe the characterization of proteins associated to tubulin dimer in its native form, using affinity chromatography and mass spectrometry. We used an immunoaffinity column with coupled-monoclonal antibody directed against the alpha-tubulin C-terminus. Tubulin was first loaded onto the column, then interphase and mitotic cell lysates were chromatographed. Tubulin-binding proteins were eluted using a peptide mimicking the alpha-tubulin C-terminus. Elution fractions were analyzed by SDS-PAGE, and a total of 14 proteins were identified with high confidence by mass spectrometry. These proteins could be grouped in four classes: known tubulin-binding proteins, one microtubule-associated protein, heat shock proteins, and proteins that were not shown previously to bind tubulin dimer or microtubules.     

Endothelial stress induces the release of vitamin D-binding protein, a novel growth factor

Endothelial cells (EC) under stress release paracrine mediators that facilitate accumulation of vascular smooth muscle cells (VSCM) at sites of vascular injury. We found that medium conditioned by serum-starved EC increase proliferation and migration of VSCM in vitro. Fractionation of the conditioned medium followed by mass spectral analysis identified one bioactive component as vitamin D-binding protein (DBP). DBP induced both proliferation and migration of VSMC in vitro in association with increased phosphorylation of ERK 1/2. PD 98059, a biochemical inhibitor of ERK 1/2, abrogated these proliferative and migratory responses in VSMC. DBP is an important carrier for the vitamin-D sterols, 25-hydroxyvitamin-D, and 1alpha,25-dihydroxyvitamin-D. Both sterols inhibited the activity of DBP on VSMC, suggesting that vitamin D binding sites are important for initiating the activities of DBP on VSMC. Release of DBP at sites of endothelial injury represents a novel pathway favoring accumulation of VSMC at sites of vascular injury.     

Evidence of finely tuned expression of DNA polymerase beta in vivo using transgenic mice

DNA polymerase (Pol) is an error-prone repair DNA polymerase that has been shown to create genetic instability and tumorigenesis when overexpressed by only 2-fold in cells, suggesting that a rigorous regulation of its expression may be essential in vivo. To address this question, we have generated mice which express a transgene (Tg) bearing the Pol cDNA under the control of the ubiquitous promoter of the mouse H-2K gene from the major histocompatibility complex. These mice express the Tg only in thymus, an organ which normally contains the most abundant endogenous Pol mRNA and protein, supporting the idea of a tight regulation of Pol in vivo. Furthermore, we found no tumor incidence, suggesting that the single Pol overexpression event is not sufficient to initiate tumorigenesis in vivo.     

Evidence for genetic control of adult weight plasticity in the snail Helix aspersa

Phenotypic plasticity and canalization are important topics in quantitative genetics and evolution. Both concepts are related to environmental sensitivity. The latter can be modeled using a model with genetically structured environmental variance. This work reports the results of a genetic analysis of adult weight in the snail Helix aspersa. Several models of heterogeneous variance are fitted using a Bayesian, MCMC approach. Exploratory analyses using posterior predictive model checking and model comparisons based on the deviance information criterion favor a model postulating a genetically structured heterogeneous environmental variance. Our analysis provides a strong indication of a positive genetic correlation between additive genetic values affecting the mean and those affecting environmental variation of adult body weight. The possibility of manipulating environmental variance by selection is illustrated numerically using estimates of parameters derived from the snail data set.     

Population-based cervical screening with a 5-year interval in The Netherlands. Stabilization of the incidence of squamous cell carcinoma and its precursor lesions in the screened population

OBJECTIVE: To evaluate the outcome of population-based cervical screening at 5-year intervals. STUDY DESIGN: Results from the west region of the Netherlands (population 2 million) were used. The 1995-2000 round was compared with the first 2 years of the second (2001-2002). All results were prospectively collected in a central database. Positive cytologies and histoscores per 1,000 screened for preinvasive squamous cervical intraepithelial neoplasia (CIN) lesions and invasive squamous cell carcinoma were calculated. RESULTS: In the first round, 378,081 women were screened; in the second round, 100,561 women were screened. In both rounds the youngest screenees had the highest cytoscores. Cytoscores in the first round did not differ significantly from those in the second. The histoscore for CIN 1 and 2 was 1.42 per 1,000 in the first round and 1.18 per 1,000 (NS, P < .01) in the second. The histoscore for CIN 3 was 2.07 per 1,000 in the first round and 2.13 per 1,000 (NS, P < .01) in the second. Histoscores for invasive squamous cell carcinoma remained virtually the same (0.16 per 1,000 in the first, 0.14 per 1,000 in the second round). CONCLUSION: Population-based screening at 5-year intervals in the Netherlands may result in stabilization of positive cytology and of the incidence of CIN and (histologic) invasive squamous cell carcinoma. The program seems more cost effective than that of 2 decades ago, with a screening interval of 3 years.     

Optimized quality of histologic images allows the use of neural network scanning in diagnosis of fungal infection of abnormal nails

OBJECTIVE: The neural network scanning (NNS) system, formerly known as Papnet, is capable of selecting fungi in cervical smears. The objective of this study was to investigate whether the optimized quality of histologic images created using a combination of coagulant fixation and microwave histoprocessing allows the application of this computer-assisted microscopy in the diagnostic process. STUDY DESIGN: In a prospective study, 117 abnormal nails clinically suspect for fungal disease werefixed in a coagulant fixative, BoonFix, processed in a microwave histoprocessor to obtain optimal paraffin sections and stained with the periodic acid-Schiff (PAS) method. The stained paraffin sections were randomly numbered and screened by two independent pathologists for diagnosis of fungal hyphae and spores. The same sections were subsequently scanned by a neural network, and a maximum of 128 digital images produced by the system were screened and diagnosed by pathologists. Using light microscopy as the gold standard for diagnosis of fungi, the usefulness of NNS was then assessed. RESULTS: The fungi and spores were clearly demonstrated in the paraffin sections, and the NNS system detected and recorded them efficiently. The hyphae and spores could be identified in these pixilated images with relative ease. Of the 117 examined cases, 50 were positive and 47 negative by both methods. In the 20 remaining cases, NNS did not present images of fungi that were present in the histologic sections. In practice, this implies that only 67 out of 117 cases (57%) must be screened by light microscopy. NNS recorded not only fungi and spores in the 128 digital images but also artifacts, such as round, deeply PAS-positive granules of talcum powder, which by light microscopy might be mistaken for fungal spores. CONCLUSION: NNS proves applicable for the selection of spores and fungi if the histologic sections are of sufficiently high quality. As a result, the number of slides to be screened by light microscopy can be reduced substantially. In a throughput diagnostic laboratory handling a large number of such cases this technology can be highly valuable.     

Sulfated HNK-1 epitope in developing and mature kidney: a new marker for thin ascending loop of Henle and tubular injury in acute tubular necrosis.

The HNK-1 carbohydrate epitope is a 3-sulfo-glucuronyl residue attached to lactosamine structures on glycoproteins, proteoglycans, or glycolipids mostly expressed in the nervous system. Here, using monoclonal antibodies against the sulfated HNK-1 carbohydrate epitope, we first examined its distribution in developing and adult kidneys, then its expression in kidneys with tubular necrosis and renal neoplasms. This HNK-1 epitope was expressed in the human, rabbit, and rat, but not mouse kidney. It was detected within a subset of epithelial cells in the renal vesicle and in comma- and S-shaped bodies during early stages of nephrogenesis. In ureteral bud derivatives, the epitope was present transiently in the area where the collecting duct fused with the nephron. In the adult kidney, expression of the HNK-1 epitope became mainly restricted to the thin ascending loop of Henle where this epitope was carried by heparan- and chondro-proteoglycan. In pathological conditions, HNK-1 epitope expression increased dramatically in proximal epithelial tubule cells in kidneys with acute tubular necrosis. In tumors, the HNK-1 epitope was expressed in the epithelial component of nephroblastomas and in a subgroup of papillary renal cell carcinomas. These data suggest that molecules carrying the sulfated HNK-1 carbohydrate epitope may play an important role in critical stages of renal development and in the physiology of thin ascending loop of Henle.