Chemical and physical guidance of fish spermatozoa into the egg through the micropyle†,‡

Eggs of teleost fish, unlike those of many other animals, allow sperm entry only at a single site, a narrow canal in the egg's chorion called the micropyle. In some fish (e.g., flounder, herring, and Alaska pollock), the micropyle is a narrow channel in the chorion, with or without a shallow depression around the outer opening of micropyle. In some other fish (e.g., salmon, pufferfish, cod, and medaka), the micropyle is like a funnel with a conical opening. Eggs of all the above fish have a glycoprotein tightly bound to the chorion surface around the micropyle. This glycoprotein directs spermatozoa into the micropylar canal in a Ca2+-dependent manner. This substance, called the micropylar sperm attractant or MISA, increases fertilization efficiency and is essential in herring. In flounder, salmon, and perhaps medaka, fertilization is possible without MISA, but its absence makes fertilization inefficient because most spermatozoa swim over the micropyle without entering it. The mechanism underlying sperm-MISA interactions is yet to be determined, but at least in herring the involvement of Ca2+ and K+ channel proteins, as well as CatSper and adenylyl cyclase, is very likely. In some other fish (e.g., zebrafish, loach, and goldfish), the chorion around the micropyle is deeply indented (e.g., zebrafish and loach) or it has radially or spirally arranged grooves around the outer opening of the micropyle (e.g., goldfish). MISA is absent from the eggs of these fish and sperm entry into micropylar canal seems to be purely physical.

Effects of soluble copper and copper oxide nanoparticle exposure on the immune system of mussels, Mytilus galloprovincialis

Copper and copper oxide nanomaterials (nCuO) can enter the marine environment negatively impacting mussels, an environmental and commercially relevant organism. We analyzed the effects on the immune system of adult mussels exposed to soluble copper (CuSO₄ , 20-50 μg/L) or nCuO (100-450 μg/L). CuSO₄ caused significant copper accumulation in gills and cell-free hemolymph, while nCuO caused cell damage to gills and significant copper accumulation in hemocytes, the most abundant cells in the hemolymph. Both sources of copper caused cellular toxicity in hemocytes by increasing reactive oxygen species production and lysosome abundance, and decreasing multi-drug resistance transporter activity. Though hemocyte abundance was not affected, their in-vitro phagocytic activity decreased, explaining the slight (but not statistically significant) increase in bacterial proliferation in mussels exposed to the pathogenic bacteria Vibrio tubiashii following copper exposure. Thus, exposure to non-lethal concentrations of CuSO₄ or nCuO can potentially increase mussel susceptibility to bacterial infections.

Drug and radiation sensitivity measurements of successful primary monolayer culturing of human tumor cells using cell-adhesive matrix and supplemented medium

The limitations of the agar suspension culture method for primary culturing of human tumor cells prompted development of a monolayer system optimized for cell adhesion and growth. This method grew 83% of fresh human tumor cell biopsy specimens, cultured and not contaminated, from a heterogeneous group of 396 tumors including lung cancer (93 of 114, 82%); melanoma (54 of 72, 75%); sarcoma (46 of 59, 78%); breast cancer (35 of 39, 90%); ovarian cancer (16 of 21, 76%); and a miscellaneous group consisting of gastrointestinal, genitourinary, mesothelioma, and unknown primaries (78 of 91, 86%). Cell growth was characterized morphologically with Papanicolaoustained coverslip cultures and cytogenetically with Giemsastained metaphase spreads. Morphological features such as nuclear pleomorphism, chromatin condensation, basophilic cytoplasm, and melanin pigmentation were routinely seen. Aneuploid metaphases were seen in 90% of evaluable cultures, with 15 of 28 showing 70% or more aneuploid metaphases. Colony-forming efficiency ranged between 0.01 and 1% of viable tumor cells, with a median efficiency of 0.2%. This culture system uses a low inoculum of 25,000 viable cells per well which permitted chemosensitivity testing of nine drugs at four doses in duplicate from 2.2 X 10(6) viable tumor cells and radiation sensitivity testing at five doses in quadruplicate from 0.6 X 10(6) cells. Cultures were analyzed for survival by computerized image analysis of crystal violet-stained cells. Drug sensitivity studies showed variability in sensitivity and in survival curve shape with exponential cell killing for cisplatin, Adriamycin, and etoposide, and shouldered survival curves for 5-fluorouracil frequently seen. Radiation sensitivity studies also showed variability in both sensitivity and survival curve shape. Many cultures showed exponential cell killing, although others had shouldered survival curves. This method for growing cells from primary human biopsy specimens is more efficient than the agar culture method, enables easier and better biological analysis of the actual cells grown, and permits improved characterization of drug and radiation survival curves.