Photochemistry Illuminates Ubiquitous Organic Matter Fluorescence Spectra.

Dissolved organic matter (DOM) in aquatic environments forms a vast reservoir of carbon present as a complex supermixture of compounds. An efficient approach to tracking the production and removal of specific DOM fractions is needed across disciplines, for purposes that range from improving global carbon budgets to optimizing water treatment in engineered systems. Although widely used to study DOM, fluorescence spectroscopy has yet to deliver specific fractions with known spectral properties and predictable distributions. Here, we mathematically isolate four visible-wavelength fluorescent fractions in samples from contrasting lake, river, and ocean environments. Using parallel factor analysis (PARAFAC), we show that most measured fluorescence in environmental samples can be explained by ubiquitous spectra with nearly stable optical properties and photodegradation behaviors over environmental pH gradients. Sample extraction changed bulk fluorescence spectra but not the number or shape of underlying PARAFAC components, while photobleaching preferentially removed the two longest-wavelength components. New approaches to analyzing fluorescence data sets incorporating these findings should improve the interpretation of DOM fluorescence and increase its utility for tracing organic matter biogeochemistry in aquatic systems.

[Primary cutaneous and metastasing haemangiosarcoma in an addax (Addax nasomaculatus)]. / Primäres, kutanes, metastasierendes Hämangiosarkom bei einer Mendesantilope (Addax nasomaculatus).

Neoplastic diseases were described very rarely in addax (Addax nasomaculatus). In this communication clinical signs, morphological and immunohistological findings in a 15-year-old, female addax with a primary cutaneous, re-occurring and metastasing haemangiosarcoma of a forelimb are reported.

[Tracheal collapse in a four month old Uckermaerker heifer]. / Trachealkollaps bei einem vier Monate alten Uckermärker Jungrind.

This report describes a case of tracheal collapse in a four month old Uckermaerker heifer. The animal was born spontaneous without signs of dystocia. It was kept outside on the pasture and died in the summer at high temperatures under signs of acute dyspnea and respiratory failure. Clinical symptoms were not observed by the owner until a few hours before death. At necropsy, the middle and caudal third of the trachea was found to be collapsed due to an inward bending of the dorsal ends of the cartilage rings. The most severe luminal reduction was located in the thoracic part of the trachea approximately 5 cm cranial the tracheal bronchus. Additional pathological lesions were absent except for signs of circulatory failure (lung edema, congestion of the shock organs). Based on clinical history and pathological findings, a traumatic cause of the tracheal collapse is unlikely. However, a hereditary influence seems possible since analysis of the breeding scheme revealed inbreeding. The mother of the affected animal was mated with her grandson (inbreeding coefficient 0,125).

CaBP1, a calcium binding protein of the thioredoxin family, is a resident KDEL protein of the ER and not of the intermediate compartment.

A cDNA encoding rat CaBP1 has been isolated and sequenced. The deduced polypeptide chain consists of 440 amino acids including two internal thioredoxin-like domains and a C-terminal KDEL retention/retrieval signal. Regarding the high degree of identity to the hamster protein P5, CaBP1 is considered to be the homologous rat protein. Previous work has suggested that CaBP1 is a resident luminal protein of the intermediate compartment (Schweizer, A., Peter, F., Nguyen Van, P., Söling, H.D. and Hauri, H.P. (1993) Eur. J. Cell Biol. 60, 366-370). Our conclusion that CaBP1 is a resident protein of the endoplasmic reticulum and not of the intermediate compartment is based on three different approaches: subcellular fractionation, indirect immunofluorescence and overexpression of CaBP1. Subcellular fractionation of Vero cells in a velocity controlled step gradient led to copurification of CaBP1-containing vesicles and several marker proteins for the ER including calreticulin and alpha-SSRP. The intermediate compartment, as defined by a monoclonal antibody against the marker protein p53 (ERGIC-53), could be separated from these ER markers. Double immunofluorescence analysed by laser scanning microscopy showed no significant colocalization between CaBP1 and p53, but between CaBP1 and calreticulin. In addition experiments, Vero cells were infected with VSV tsO45. At 15 degrees C the VSV-G protein accumulated in punctuate structures representing the intermediate compartment, while CaBP1 maintained its original reticular localization. Even after high-level overexpression in COS cells, CaBP1 was not detected in the intermediate compartment, but was efficiently retained in the ER as judged by light microscopy.