Serology of Naegleria fowleri and Naegleria lovaniensis in a Hospital Survey1

An avidin-biotin horseradish peroxidase method was used to detect antibodies to Naegleria fowleri and N. lovaniensis in human serum samples. Antibodies were detected in 101 specimens from 115 hospital patients ranging in age from 15 to 98 years. Class-specific anti-immunoglobulins identified antibodies as IgG and IgM. IgG antibody titers to both species ranged from 1:20 to 1:640. Seven of 15 serum samples collected from newborn infants also demonstrated IgG antibodies to these organisms with a titer range of 1:20 to 1:80. The immunoperoxidase test and Western blot analysis of selected serum samples demonstrated a close similarity in serological results between N. fowleri and N. lovaniensis.     

Resistance to raspberry cane midge (Resseliella theobaldi) and its association with wound periderm in Rubus crataegifolius and its red raspberry derivatives

Rubus parviflorus, R. odoratus and F₂ plants from the cross R. crataegifolius x R. idaeus were resistant to the raspberry cane midge (Resseliella theobaldi) when exposed to the pest in an insectary or in the field. Histological studies of R. crataegifolius and one of its hybrids with R. idaeus showed that resistance was associated with a wound periderm of suberised and lignified cells. These cells were formed from the primary cortex and phelloid cells of the polyderm as a rapid response to the occurrence of natural splits and wounds which are the oviposition sites of R. theobaldi. In the hybrid, new tissues from this wound periderm prevented the peeling of the mature primary cortex, thereby precluding serious midge attack, and resulted in a reticulate appearance on the cane surface, a distinctive cane feature useful for identifying resistant segregates.     

The Effect of Salinity on Growth of Phaseolus vulgaris L.: II. Effect on Internal Solute Concentration

This paper reports the changes which occurred in the concentrationof ions, organic acids, sugars and polyhydric alcohols whenplants of Phaseolus vulgaris were grown in culture solutioncontaining 48 m mol l^–1 sodium chloride. Attention wasfocused particularly on the changes in the primary and firsttrifoliate leaves. In the latter leaves of salt-treated plantsthere were initially very high concentrations of sodium andmuch higher concentrations of glucose and inositol than in controlleaves. Subsequently concentrations of these solutes declined,the decline of sodium being due to retranslocation out of theleaf. There were no striking differences between the concentrationof organic solutes of the primary leaves of salt-treated plantsand those of control plants. There were greater concentrationsof ions in the salt-treated primary leaves, particularly a greaterconcentration of potassium (though that in the medium was thesame in both treatments). While the calcium concentrations inboth sets of primary leaves were very similar, it appeared thatin the leaves of salt-treated plants much of the ion is solublewithin the cells while in the leaves of the control plants,most of the ion is thought to be associated with the cell wall.There was a greater concentration of organic acids in the leavesof the control plants but in both treatments, primary and trifoliateleaves each had a similar composition of acids. Sodium ionswere restrained from entering the leaves by selection againstthe ion in favour of potassium in the root and possibly by retentionof sodium in the stem. The data on solute concentrations togetherwith calculated values of cellular osmotic potentials are discussedin relation to the development of the first trifoliate leaves.     

Mechanistic Basis of Life-History Evolution in Anuran Amphibians: Direct Development

SYNOPSIS. The primitive, or ancestral reproductive mode forRecent amphibians involves a complex, biphasic life history.Yet evolutionarily derived, alternate modes are seen in allthree living orders and predominate in some clades. Analysisof the consequences and mechanistic bases of one such mode—directdevelopment—can provide insights into the evolutionaryopportunities and constraints conferred by the ancestral metamorphicontogeny. Direct development in the anuran genus Eleutherodactylusinvolves fundamental alterations to many features of embryonicand posthatching development. At hatching, young emerge as fullyformed, albeit tiny versions of the adult; most larval featuresare absent. Pervasive changes in ontogenetic timing, in particularthe precocious (embryonic) formation of many adult structures,appear to be correlated with early development of the thyroidaxis, although responsiveness to exogenous thyroid hormone isdiminished or even lacking in at least some peripheral tissues.Changes in cranial patterning are likely mediated by the embryonicneural crest, although many gross features of crest biologyare highly conserved. Laboratory-based analyses of direct developmentand other derived reproductive modes in amphibians, using contemporarymethods developed for more standard, "model" organisms, maycontribute important insights into life-history evolution thatcomplement those derived from analyses of morphology, ecologyand phylogeny.     

Further studies on breeding for resistance to Botrytis cinerea in red raspberry canes

A high level of resistance to cane botrytis caused by Botrytis cinerea was transferred from Rubus pileatus to the red raspberry through three generations of backcrossing. The strength of the resistance showed little diminution through these generations and it was therefore thought that a major gene for resistance had been transferred. But discontinuity in the resistance levels observed was detected in plants of only one group of the progenies and so evidence for a major gene is lacking. The results showed the considerable influence of gene H, which confers pubescence, and emphasised that resistance must be separately assessed for pubescent and non-pubescent segregates.     

The active transport of Mg++ and Mn++ into the yeast cell

Certain bivalent cations, particularly Mg⁺⁺ and Mn⁺⁺, can be absorbed by yeast cells, provided that glucose is available, and that phosphate is also absorbed. The cation absorption is stimulated by potassium in low concentrations, but inhibited by higher concentrations. From the time course studies, it is apparent that the absorption rather than the presence of phosphate and the potassium is the important factor. Competition studies with pairs of cations indicate that binding on the surface of the cell is not a prerequisite to absorption. The absorption mechanism if highly selective for Mg⁺⁺ and Mn⁺⁺, as compared to Ca⁺⁺, Sr⁺⁺, and UO₂⁺⁺, whereas the binding affinity is greatest for UO₂⁺⁺, with little discrimination between Mg⁺⁺, Ca⁺⁺, Mn⁺⁺, and Sr⁺⁺. In contrast to the surface-bound cations which are completely exchangeable, the absorbed cations are not exchangeable. It is concluded that Mg⁺⁺ and Mn⁺⁺ are actively transported into the cell by a mechanism involving a phosphate and a protein constituent.     

Identification of Drosophila Yin and PEPT2 as Evolutionarily Conserved Phagosome-associated Muramyl Dipeptide Transporters

NOD2 (nucleotide-binding oligomerization domain containing 2) is an important cytosolic pattern recognition receptor that activates NF-κB and other immune effector pathways such as autophagy and antigen presentation. Despite its intracellular localization, NOD2 participates in sensing of extracellular microbes such as Staphylococcus aureus. NOD2 ligands similar to the minimal synthetic ligand muramyl dipeptide (MDP) are generated by internalization and processing of bacteria in hydrolytic phagolysosomes. However, how these derived ligands exit this organelle and access the cytosol to activate NOD2 is poorly understood. Here, we address how phagosome-derived NOD2 ligands access the cytosol in human phagocytes. Drawing on data from Drosophila phagosomes, we identify an evolutionarily conserved role of SLC15A transporters, Drosophila Yin and PEPT2, as MDP transporters in fly and human phagocytes, respectively. We show that PEPT2 is highly expressed by human myeloid cells. Ectopic expression of both Yin and PEPT2 increases the sensitivity of NOD2-dependent NF-κB activation. Additionally, we show that PEPT2 associates with phagosome membranes. Together, these data identify Drosophila Yin and PEPT2 as evolutionarily conserved phagosome-associated transporters that are likely to be of particular importance in delivery of bacteria-derived ligands generated in phagosomes to cytosolic sensors recruited to the vicinity of these organelles.     

Electrophysiological Evidence for an Electrogenic Proton Pump and the Proton Symport of Glucose in the Marine Fungus Dendryphiella salina

The marine hyphomycete Dendryphiella salina (Suth.) Nicot &Pugh has a resting membrane potential of –250 mV (insidenegative). The respiratory inhibitors sodium azide and FCCPinduced a rapid but reversible depolarization of the membraneof at least 180 mV; sodium azide also caused alkalinizationof the medium. Vanadate brought about significant depolarizationbut this was not always reversible. EDTA induced depolarizationthough to a lesser extent. DIDS and SITS caused a depolarizationof around 30–70 mV which was readily reversible, N-ethylmaleimideirreversibly depolarized the membrane by 180–200 mV. Ouabainhad no effect. When external concentrations of H⁺ , K⁺ , Na⁺or Cl^– were changed singly, only changes in H⁺ affectedmembrane potential, with shifts decreasing with increasing pH.Glucose and 3-O-methyl glucose depolarized the membrane in aconcentration-dependent manner which was enhanced by starvationof the hyphae. Recovery occurred in the presence of the hexose.Glucose caused an alkalinization of the medium, with time characteristicssimilar to the membrane potential changes. It is concluded thatthere is an electrogenic proton pump and a proton—glucosesymporter in D. salina. The retention of proton-based transportsystems suggests a terrestrial origin for the fungus. Key words: Marine fungi, Dendryphiella salina, membrane potential, electrogenic proton pump, proton symport, hexose