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.     

Phorbol esters as probes of the modulatory site on protein kinase G–an overview

Phorbol esters as probes of the modulatory site on protein kinase C–an overview. The phorbol esters, diterpene derivatives produced by members of the family Euphorbiaceae, are of major scientific importance as tumour promoters. Their primary site of action is protein kinase C, an enzyme involved in the message transduction pathway for a large class of hormones which cause enhanced phosphatidylinositol turnover. Heterogeneity in the response of biological systems to the phorbol esters may be explained in part by heterogeneity in the phospholipids associated with protein kinase C, in its subcellular localization, and by proteolytic processing, as well as by isoforms of the enzyme. Development of other classes of activators of protein kinase C through computer modelling and natural product isolation suggests possible new approaches for intervention in the pathway.     

Hiatal shell concentrations, sequence analysis, and sealevel history of a Pleistocene coastal alluvial fan, Punta Chueca, Sonora

Richly fossiliferous marine sediments exposed along the Sonoran coastline of the Gulf of California near Punta Chueca provide an excellent setting in which to test (a) the strength of the association of skeletal concentrations with sedimentary hiatuses, (b) the utility of taphonomic evidence for reconstructing detailed histories of those non-depositional episodes, and thus (c) the largely unexploited potential of skeletal concentrations in the identification and interpretation of lithologically obscure unconformities and condensed sequences in shallow marine deposits. Sequence analysis based on discontinuity surfaces is possible in the complex, alluvial fan-to-shallow marine transition at Punta Chueca despite rapid facies changes. Progradation of depositional sequences that contain cobbles reworked from older terrace deposits indicates accumulation during a fall in eustatic sea level. The supratidal to subtidal conglomerates and sands contain a variety of predominantly molluscan shell concentrations that, on the basis of postmortem histories of shells, formed during periods of low net sedimentation (i.e. depositional hiatuses); the majority of these shell beds lie along discontinuity surfaces identified by independent physical stratigraphic evidence. Although not all discontinuity surfaces in the terrace are paved by shell material. and not all relative concentrations of shells indicate distinct discontinuities, the strength of the association between skeletal concentrations and stratigraphic hiatuses reveals the high degree of control on fossil occurrence by sedimentation rates, and indicates that skeletal concentrations can provide good clues to stratigraphically significant surfaces. Moreover, the detailed dynamics of non-depositional episodes are reliably revealed by taphonomic analysis of the associated fossil assemblages, improving interpretations of non-depositional episodes in local sedimentary history.     

Phenology of nutritional differences between new and mature leaves and its effect on caterpillar growth

Abstract. 1. We determined the phenology of the shrub Spiraea latifolia Ait. Bork. (Rosaceae), which has indeterminate shoot growth, and the effects of phenological changes in leaf quality on growth rate of the early-spring feeding buckmoth caterpillars, Hemileuca lucina Hy. Edw. (Saturniidae).
2. Leaves, regardless of whether they were newly expanded or several weeks old, were tougher later in the growth season (mid-June) than similarly aged leaves collected earlier; correspondingly, water and nitrogen content for leaves of all ages declined through the larval period. By July, newly expanded leaves had no more nitrogen than mature leaves.
3. Relative growth rate of third instar larvae fed new leaves or a mixture of new and mature leaves in early June was higher than that of those fed mature leaves, and efficiency of conversion of digested food to biomass was higher for larvae fed new leaves than for those fed mature leaves or a mixture.
4. In another experiment, larvae were reared on new leaves through the fourth instar and then fed a diet of new, mature or a combination of new and mature leaves, a regimen that was similar to the phenologies of both plants and caterpillars in the field. There was no difference in time to pupation or pupal weights among these treatments.     

Heterophylly in Ranunculus flabellaris: The Effect of Abscisic Acid on Leaf Ultrastructure

Ranunculus flabellaris Rafin., an aquatic buttercup, exhibitsheterophylly at the level of cellular ultrastructure. Comparedto terrestrial leaves, underwater leaves have thinner epidermalcell walls and more numerous paramural bodies per epidermaland mesophyll cell cross-section. The number of chloroplastsand mitochondria in cell cross-sections also contrasts betweenthe two leaf types. Despite within-and between-leaf variations,different patterns of organelle distribution for the two leafforms were found using principal coordinates analysis. In addition,underwater leaf chloroplasts are smaller, have fewer grana,a greater number of thylakoids/granum, and less starch comparedto chloroplasts from terrestrial leaves. At the ultrastructurallevel, submergence in ABA solution does not produce a leaf withas many characteristics of the terrestrial environment, as shownin previous studies of leaf morphology and anatomy. While numberand distribution of organelles in ABA-treated leaves are similarto terrestrial leaves, some features of chloroplast internalstructure and paramural body number and distribution resembleunderwater leaves. It is postulated that ABA acts as a morphogeninvolved in guiding the irreversible processes of leaf development,but certain subcellular characteristics may be determined directlyby the physical environment. Difficulties encountered in quantitativeanalyses of cellular ultrastructure are discussed. Ranunculus flabellaris, ABA, heterophylly, leaf ultrastructure, principal coordinates analysis     

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