Spatio-temporal heterogeneity in river sounds: Disentangling micro- and macro-variation in a chain of waterholes

1. Passive acoustic monitoring is gaining momentum as a viable alternative method to surveying freshwater ecosystems. As part of an emerging field, the spatio-temporal replication levels of these sampling methods need to be standardised. However, in shallow waters, acoustic spatio-temporal patchiness remains virtually unexplored.
2. In this paper, we specifically investigate the spatial heterogeneity in underwater sounds observed within and between waterholes of an ephemeral river at different times of the day and how it could affect sampling in passive acoustic monitoring.
3. We recorded in the Einasleigh River, Queensland in August 2016, using a linear transect of hydrophones mounted on frames. We recorded four times a day: at dawn, midday, dusk, and midnight. To measure different temporal and spectral attributes of the recorded sound, we investigated the mean frequency spectrum and computed acoustic indices.
4. Both mean frequency spectrum and index analyses revealed that the site and diel activity patterns significantly influenced the sounds recorded, even for adjacent sites with similar characteristics along a single river. We found that most of the variation was due to temporal patterns, followed by between-site differences, while within-site differences had limited influence.
5. This study demonstrates high spatio-temporal acoustic variability in freshwater environments, linked to different species or species groups. Decisions about sampling design are vital to obtain adequate representation. This study thus emphasises the need to tailor spatio-temporal settings of a sampling design to the aim of the study, the species and the habitat.

     

Short-term boron deprivation enhances levels of cytoskeletal proteins in maize, but not zucchini, root apices

By using indirect immunofluorescence microscopy and Western blot analysis, we have demonstrated increased levels of actin and tubulin proteins as well as an altered polymerization pattern of their cytoskeletal assemblies in maize, but not zucchini root apices, as a response to early boron deprivation. Northern blot analysis, however, did not show significant increases in the amount of steady-state mRNAs of actin and tubulin. This finding indicates that these rapid cytoskeletal responses to boron removal are very likely regulated at translational/post-translational levels. Interestingly, these increased levels of cytoskeletal proteins coincided well with a reduction in the water-extractable, but not with the cell wall-bound, fraction of boron. This implicates that free boric acid, or other more labile boron complexes, might be involved in the activation of cytoskeletal responses in maize root apices. In fact, our experimental approach revealed that maize was suffering from boron deprivation as early as zucchini. This was evidenced by its slightly reduced root elongation rate recorded within 3–5 h of boron deprivation. Importantly, however, maize roots can recover from this early inhibition indicating an effective adaptation mechanism. In contrast, zucchini roots apparently lack this boron-deprivation response pathway and suffer extensively when exposed to boron-free environment. This leads to the tentative working hypothesis for an adaptive mechanism of maize roots to boron deprivation by enhancing its cytoskeletal protein levels and altering their polymerization patterns in order to mechanically reinforce the cell periphery complex of their cells. This testable hypothesis requires further experimental verification.     

Fc receptors and surface immunoglobulins in cells of hairy cell leukemia]

Using 125I-labelled aggregated IgG in a quantitative assay a strong expression of Fc-receptors was found on the leukemic cells of a patient with hairy cell leukemia. The Fc-receptor activity on these cells was much higher than that on monocytes and B-lymphocytes from normal blood. Surface immunoglobulins were detected by radioautography using radioactively labelled (Fab')2-fragments of monospecific antibodies directed against immunoglobulin heavy chains. Prior to radioautography the cells were stained for the tartrate resistant acid phosphatase. It was found that all cells containing this enzyme bore sigma-chains on their surface. On more than 90% of these cells a simultaneous expression of mu-chains was detected. gamma-Chains could only be demonstrated on cells which were negative for the tartrate resistant acid phosphatase; part of these cells, however, were hairy cells by morphological criteria.     

Isolation of acid producing sorbitol-adapted bacteria from dental plaque using selective agar media

Acidogenic bacteria metabolizing sorbitol were isolated and identified from dental plaque of twenty nine volunteers, claiming to be users (sixteen) and non-users (thirteen) of sorbitol-containing chewing gum and candy. Sixty bacterial strains were isolated, using improved selective agar media. The taxonomy of twenty strains, all Gram-positive cocci, was determined employing a customized BBL MinitekR system and other biochemical reactions. The majority of these strains represented Streptococcus sanguis and Streptococcus acidominimus. Although sorbitol-metabolizing bacteria were found in plaque specimens of most persons tested, a larger number of acidogenic sorbitol degrading bacteria was detected in the plaque of the volunteer group claiming to use sorbitol-containing sweets. Bacteriological results indicate that frequent consumption of sorbitol-containing products will lead to a shift in oral ecology, numerically favouring sorbitol-metabolizing bacteria. These sorbitol adapted bacteria appear to be as acidogenic as Streptococcus mutans in the presence of ordinary sugars.