Occurrence of bacterivory in Cryptomonas,a common freshwater phytoplankter

Summary Bacterivory was detected by incorporation of 0.57 m diameter, fluorescent polystyrene beads and fluorescently labeled bacteria (FLB) in two cultured species of Cryptomonas (C. ovata and C. erosa), and a population of Cryptomonas sp in a humic, mesotrophic lake. Rates of ingestion and clearance were very low, and similar for the cultures and the in situ population. The in situ population incorporated 0.7–1.7 bacteria cell^-1 h^-1, thereby ingesting 0.3%–2.0% of the total bacterial numbers present in the water per day, and receiving less than 2% of its carbon content per day through bacterivory. Thus, bacterivory by Cryptomonas was quantitatively important neither as a sink for bacterial biomass, nor as a carbon source for the algal cells. Possibly, it served in the uptake of essential nutrients.     

Evaluation of Diverse Antisera, Conjugates, and Support Media for Detecting Bradyrhizobium japonicum by Indirect Enzyme-Linked Immunosorbent Assay

We evaluated three antisera and four enzyme conjugates for the detection of Bradyrhizobium japonicum by an indirect enzyme-linked immunosorbent assay in microtiter plates. Nitrocellulose membrane sheets were then evaluated as an alternative support medium by using some combinations. Partially purified immunoglobulin G (IgG) or unpurified antisera to strain USDA 110 raised in rabbits, goats, or sheep was reacted in microtiter plates with alkaline phosphatase conjugated to protein A, goat anti-rabbit (GAR), sheep anti-rabbit (SAR), or rabbit anti-goat (RAG) IgG. Cultures or nodules containing homologous rhizobia were detected with equal sensitivity when protein A, GAR, or SAR was reacted with 5 μg of protein IgG per ml or a 1:800 titer of antisera from rabbits, but not goats or sheep. RAG reacted with IgG or antisera from goats or sheep. The detection limit was 2 × 10⁵ rhizobia per well. Rhizobia were spotted on nitrocellulose sheets as an alternative support medium, followed by soaking in 5 μg of protein per ml as IgG and 1:4,000 dilutions of protein A or GAR conjugate. Rhizobia in serogroup 110 were detected with the dye combination Nitro Blue Tetrazolium-5-bromo-4-chloro-3-indolyl phosphate (NBT-BCIP), and rhizobia in serogroup 122 were detected with fast red-naphthol phosphate (FR-NP). At the conclusion of the 5-h assay, purple (NBT-BCIP) or red (FR-NP) spots were visible in positive reactions. The sensitivity of detection was about 1,000 rhizobial cells or 3 μg of nodules tissue.     

Behavioral and biochemical assessment of time-related changes in globus pallidus and striatal dopamine induced by intranigrally administered neurotensin

Microinjection of neurotensin (NT; 2 and 5 μg) into the substantia nigra zona compacta caused an increase in dopamine (DA) and DA metabolites in the rodent globus pallidus and striatum which persisted for at least 20 hours after peptide administration. Similar NT treatments given unilaterally into the nigra caused circling away from the injected side in amphetamine-pretreated rats, but were without effect when microinjected into saline-pretreated animals. Circling also occurred when the animals were given amphetamine 20 hours after intranigral NT administration. Contralateral rotation was observed with unilateral intranigral injections of gamma-hydroxybutyric acid (GHB; 400 μg) or with lower intranigral GHB doses (250 μg) in amphetamine-pretreated animals. The effects of GHB and NT differed in the manner in which the animals rotated as well as in the profile of DA and DA metabolite changes induced by these drugs. These studies indicated that: (1) dopaminergic functions of the globus pallidus are influenced, like the striatum, by manipulations of the substantia nigra; (2) NT and GHB likely act via different mechanisms to effect nigral dopamine-containing cells; and (3) NT was capable of inducing changes in dopamine neurons which had long term consequences.     

Comparison of α1-Adrenergic Receptor-Stimulated Inositol Phosphate Formation in Primary Neuronal and Glial Cultures

alpha 1-Adrenergic receptor binding sites and norepinephrine-stimulated 3H-inositol phosphate (3H-InsP) accumulation were measured in primary cultures of neurons and glia from 1-day-old rat brains. The density of alpha 1-adrenergic receptor binding sites was approximately three times higher in membranes from neurons compared to glia. Although norepinephrine was slightly more potent in stimulating 3H-InsP formation in neurons than in glia, the maximal response was greater in glial cells. Norepinephrine-stimulated 3H-InsP formation remained constant for [3H]inositol prelabelling periods of 1-14 days in neurons, whereas the response increased with time in glia and was maximal after 7-10 days of prelabelling. Both the incorporation of [3H]inositol into lipid and basal levels of 3H-InsPs were lower in glial cells than in neurons, which accounted for the greater percent stimulation in glia. Pretreatment with phenoxybenzamine decreased norepinephrine-stimulated 3H-InsP formation in a dose-dependent manner in both neurons and glia by decreasing the maximal response without altering potency. HPLC separation showed that similar types of 3H-InsPs were accumulated in neurons and glial cells. These results demonstrate that alpha 1-adrenergic receptors exist on both neurons and glial cells and activate 3H-InsP accumulation in both cell types. Although receptor density is higher in neurons than in glia, the 3H-InsP response is higher in glia. This difference does not appear to be due to different receptor reserves, but may be due to differential coupling mechanisms in the two cell types.     

The structure and biological activities of the widely used protein kinase inhibitor, H7, differ depending on the commercial source.

The protein kinase inhibitor 1-(5'-isoquinolinesulfonyl)-2-methylpiperazine (H7) has been widely used because of its ability to inhibit cyclic AMP- and cyclic GMP-dependent protein kinases (PKA and PKG) and protein kinase C (PKC) at roughly equal concentrations; it is much less potent on other kinases. Previous studies in other laboratories have found that H7 samples from different commercial sources have different properties in cellular studies and protein kinase C inhibition assays. We now report the results of chemical and biological tests which show that H7 samples also differ in chemical structure, again depending on their commercial source. Chemical synthesis and NMR spectroscopy indicate that H7 from most suppliers has the structure originally proposed for H7, while "H7" from another supplier is in fact its 3-methylpiperazine positional isomer.     

X-inactivation patterns in lymphocytes and skin fibroblasts of three cases of X-autosome translocations with abnormal phenotypes

Summary X-inactivation patterns were studied by replication analyses both in lymphocytes and skin fibroblasts of two patients carrying balanced X-autosome translocations, t(X;10)-(pter;q11) and t(X;17)(q11;q11), and one patient with an unbalanced translocation t(X;22)(p21;q11). Preferential late replication of the normal X chromosome was found in lymphocytes of both patients carrying balanced translocations and in skin fibroblasts of the patient carrying the translocation t(X;17). However, skin fibroblasts of the patient with a translocation t(X;10) showed preferential late replication of the abnormal der(X) chromosome with no spreading of late replication to the autosomal segment. In the case of unbalanced translocation t(X;22) there was preferential late replication of the der(X) chromosome both in lymphocytes and skin fibroblasts. The abnormal phenotype of the patients is discussed in relation to the observed X-inactivation patterns and the variability of the patterns in different tissues.