Estimation of C3 levels in cerebrospinal fluid by electroimmunodiffusion

C3 levels have been determined by the electroimmunodiffusion technique in the CSF of patients with a wide variety of pathologies. The patients were grouped on the basis of protein content and G/A ratio of the CSF as I) patients with normal meningeal permeability and apparent absence of local gamma-globulin synthesis; II) patients with increased meningeal permeability; III) patients with characteristics of MS, i.e. increase of IgG accompanied by a normal or slightly elevated protein content, Group III showed a lower level of C3 when expressed at % of the total protein and also as % of the total protein less gamma-globulins of the CSF. Other parameters of the CSF are also recorded. It was shown that only the expression of C3 concentration relative to the total protein content of the CSF produced meaningful analytical data.     

Light and temperature mediate algal stimulation of heterotrophic activity on decomposing leaf litter

1. Recent evidence suggests that periphytic algae stimulate plant litter heterotrophs (fungi and bacteria) in the presence of light, but few studies have tested whether this stimulation varies across gradients of light, which may covary with temperature.
2. We exposed field-conditioned Typha domingensis litter to fully-crossed, short-term gradients of temperature (15, 20, 25, and 30°C) and light (0, 25, 53, 123, and 388 µmol quanta m⁻² s⁻¹) and measured responses of litter-associated algal, fungal, and bacterial production rates and β-glucosidase, β-xylosidase, and phenol oxidase enzyme activities in the laboratory.
3. Increased light stimulated algal production rates, from immeasurable production under darkness to >200 µg algal C g⁻¹ detrital C hr⁻¹ at the highest light level, with the greatest light sensitivity and maximal photosynthetic rates at 25°C. In turn, increased light stimulated fungal production rates, especially at the two highest temperatures and most strongly at 25°C where light stimulated fungal production by a mean of 65 µg C g⁻¹ detrital C hr⁻¹, indicating 2.1-fold stimulation by light. Bacterial production rates also responded to light, indicated by stimulation of a mean of 16 µg C g⁻¹ detrital C hr⁻¹ (1.6-fold) at 15°C, but stimulation was weaker at higher temperatures. Enzyme activities increased strongly with elevated temperature but were not affected by light.
4. Our experimental evidence suggests algae differentially stimulate litter-associated bacteria and fungi in a light-dependent manner that further depends on temperature. These findings advance understanding of the onset of algal stimulation of heterotrophy, including algal-induced priming effects during litter decomposition, in response to common covarying environmental gradients subject to global change.

     

Temporal and stoichiometric patterns of algal stimulation of litter-associated heterotrophic microbial activity

1. Periphyton communities associated with submerged plant detritus contain interacting autotrophic and heterotrophic microbes, and are sites of extracellular enzymatic activity. The strength and nature of these interactions might be expected to change over time as microbial communities develop on plant litter. Microbial interactions and enzymatic activity can be altered by nutrient availability, suggesting that litter stoichiometry could also affect these phenomena.
2. We grew wetland plants under ambient and nutrient-enriched conditions to generate plant litter of differing nutrient content. In two experiments, we investigated: (1) the influence of algal photosynthesis on fungal and bacterial production and the activities of four extracellular enzymes throughout a 54-day period of microbial colonisation and growth; and (2) the influence of litter stoichiometry on these relationships.
3. Ambient and nutrient-enriched standing-dead plant litter was collected and then submerged in wetland pools to allow for natural microbial colonisation and growth. Litter samples were periodically retrieved and transported to the laboratory for experiments manipulating photosynthesis using the photosystem II inhibitor DCMU (which effectively prevents algal photosynthetic activity). Algal (¹⁴C-bicarbonate), bacterial (³H-leucine), and fungal (¹⁴C-acetate) production, and β-glucosidase, β-xylosidase, leucine aminopeptidase, and phosphatase activities (MUF- or AMC-labelled fluorogenic substrates) were measured under conditions of active and inhibited algal photosynthesis.
4. Photosynthesis stimulated overall fungal and bacterial production in both experiments, although the strength of stimulation varied amongst sampling dates. Phosphatase activity was stimulated by photosynthesis during the first, but not the second, experiment. No other enzymatic responses to short-term photosynthesis manipulations were observed.
5. Microbial communities on high-nutrient litter occasionally showed increased extracellular enzyme activity, fungal growth rates, and bacterial production compared to communities on non-enriched litter, but algal and fungal production were not affected. Litter stoichiometry had no effects on fungal, bacterial, or enzymatic responses to photosynthesis, but the mean enzyme vector analysis angle (a measure of P- versus N-acquiring enzyme activity) was positively correlated to litter N:P, suggesting that elevated litter N:P led to an increase in the relative activity of P-acquiring enzymes.
6. These results supported the hypothesis that algal photosynthesis strongly influences heterotrophic microbial activity on macrophyte leaf litter, especially that of fungi, throughout microbial community development. However, the strength of this photosynthetic stimulation does not generally depend on small differences in litter nutrient content.
7. Stimulation of microbial heterotrophs by algal photosynthesis could drive diurnal shifts in periphyton community and aquatic ecosystem function, as well as linking green (photoautotroph-based) and brown (detrital-based) food webs.

     

Social Organization in the Guest-ant Formicoxenus provancheri

The results of an investigation on the division of labour in the guest-ant Formicoxenus provancheri, conducted by observing colonies containing individually marked adults, are presented. Five colories of Formicoxenus were installed in the laboratory with their hosts, Myrmica incompleta, in order to document, over 10 d, the location of individuals as well as individual and interactive types of behaviour. The results show that each colony of Formicoxenus consists of three groups: a group of nurses who remain in the Formicoxenus nest (some 21% of the colony's members); a group of scouts who spend most of their time in the external area (18%) and a very large group of individuals specialized in licking (‘shampooing’) the host to obtain regurgitations (61%), who essentially remain in the Myrmica nest. Division of labour in Formicoxenus appears to be a special adaptation to the xenobiotic way of life. The apparent link between social structure and the probability of profiting from trophallactic exchanges with the host species could lead to interesting predictions on the division of labour in other guest-ants.