Parasitic chytrids could promote copepod survival by mediating material transfer from inedible diatoms

Diatoms form large spring blooms in lakes and oceans, providing fuel for higher trophic levels at the start of the growing season. Some of the diatom blooms, however, are not grazed by filter-feeding zooplankton like Daphnia due to their large size. Several of these large diatoms are susceptible to chytrid infections. Zoospores of chytrids appeared to be excellent food for Daphnia, both in terms of size, shape, and quality (PUFAs and cholesterol). Thus, zoospores of chytrids can bridge the gap between inedible diatoms and Daphnia. In order to examine the effects of diatoms and chytrids on the survival of copepods, we performed one grazing and one survival experiment. The grazing experiment revealed that the diatom, Asterionella formosa, was not grazed by the copepod, Eudiaptomus gracilis, even after being infected by the chytrid Zygorhizidium planktonicum. However, carbon and nitrogen concentrations were significantly reduced by E. gracilis only when A. formosa was infected by Z. planktonicum, indicating that the chytrids might facilitate material transfer from inedible diatoms to the copepods. The survival experiment revealed that E. gracilis lived shorter with A. formosa than with the cryptophyta Cryptomonas pyrenoidifera. However, the survival of E. gracilis increased significantly in the treatment where A. formosa cells were infected by Z. planktonicum. Since E. gracilis could not graze A. formosa cells due to their large colonial forms, E. gracilis may acquire nutrients by grazing on the zoospores, and were so able to survive in the presence of the A. formosa. This provides new insights into the role of parasitic fungi in aquatic food webs, where chytrids may improve copepod survival during diatom blooms.

Relevance of C5b9 immunostaining in the diagnosis of neonatal hemochromatosis

BACKGROUND: Neonatal hemochromatosis caused by a gestational alloimmune mechanism or gestational alloimmune liver disease (GALD) is a rare perinatal disorder characterized by intra- and extrahepatic iron overload. It is believed to result from complement-mediated liver injury, in which the classical complement pathway is activated by maternal antibody/fetal antigen complexes, leading to hepatocyte lysis by the membrane attack complex C5b9. According to some authors, C5b9 expression in more than 75% of liver parenchyma is specific for GALD. // METHODS: We conducted a retrospective multicentric immunohistochemical study with anti-C5b9 in GALD cases (n = 25) and non-GALD cases with iron overload (n = 36) and without iron overload (n = 18). // RESULTS: C5b9 was expressed in 100% of GALD cases but involved more than 75% of the liver parenchyma in only 26% of the cases. C5b9 was detected in 26.75% of the non-GALD cases with more than 75% of positive parenchyma in maternal erythrocytic alloimmunization, herpes and enterovirus hepatitis, bile acid synthetic defect, DGUOK mutation, Gaucher disease, cystic fibrosis, and giant-cell hepatitis with autoimmune hemolytic anemia. // CONCLUSION: Diagnosis and therapeutic management of GALD cannot only be based on C5b9 expression in liver samples as it is not specific of this disease

Strong impact of micrometastatic tumor cell load in patients with esophageal carcinoma

BACKGROUND: To assess the role of immunohistochemically detectable nodal microinvolvement of patients with "curatively" resected esophageal carcinoma. METHODS: In 73 patients with resectable esophageal carcinoma [squamous cell carcinoma (SCC), n = 45 (61.6%); adenocarcinoma (AC), n = 28 (38.4%)] a total of 2174 lymph nodes (LN) were removed. In each of the 1958 LN classified as negative on conventional histopathology, immunohistochemistry was performed using the anticytokeratin antibody AE1/AE3. To determine the role of the amount of residual tumor load, the patients were grouped according to the percentage of LN affected with micrometastasis (0%, or =11%). RESULTS: Tumor cells were immunohistochemically detected in 47 LN (2.4%) from 25 (34.2%) patients. Five-year overall survival probability (5-YSP) of 30% in pN(0 )patients with detected occult tumor cells in LN was significantly worse than that in those without nodal microinvolvement (76%, P = 0.021), hereby resembling that of pN1-patients (24%, P = 0.84). Median overall survival in patients with no (0%), low (11%) micrometastatic tumor load was 43, 27, and 11 months, respectively. Substratification according to histological type showed that, in patients with AC, the presence of nodal microinvolvement had a significant impact on 5-YSP (0% versus 65%; P = 0.03), whereas in patients with SCC, differences of 5-YSP were only of borderline significance (24% versus 53%; P = 0.081). CONCLUSION: Minimal tumor cell load as assessed by the ratio of micrometastatically affected LN is a complementary tool for better risk stratification of patients with esophageal carcinoma