The Effect of Epidermal Wounds on the Uptake and Transport of Solutions Fed to Stems and Petioles of Plants

Incisions used to offer radioisotopes and conditioning chemicalswere monitored for their effect on the transport system, usingmovement of ¹¹C-photosynthate and ¹⁴C-sucrose to study phloemtransport in Helianthus and India ink to study xylem water movementin Heracleum. It was found that cuts made in air were more effectivethan cuts made under water, in part because both radioisotopesand conditioning chemicals penetrated more readily when cutswere made in air. Incisions made while the stem was under abackpressure, created by a pressure bomb, neutralized the releaseof pressure by the cut as seen in the movement of India inkin the xylem and biopotential changes as seen in vascular bundles. Key words: Phloem transport, Epidermal-wounding     

Relative contributions of environmental and maternal factors to trans‐generational immune priming in T. castaneum

1. Trans‐generational immune priming is a phenomenon in insects in which the offspring of mothers previously challenged with a focal microbe exhibit a survival advantage when challenged with that microbe. 2. Maternal egg provisioning with immune factors such as antimicrobial peptides (AMPs) is widely believed to contribute to the primed phenotype. However, other ‘socially mediated’ environmental factors secreted or excreted by the mother and others in the community, such as the gut microbiota or pheromones, may also affect offspring immune phenotype. 3. The relative contributions of maternal egg provisioning and socially mediated environmental factors to the primed larval phenotype were assessed by performing a cross‐fostering survival experiment with Tribolium castaneum, in which the eggs of primed or naïve mothers were sterilised, treated with the frass of primed or naïve beetles, and challenged as larvae with the maternal pathogen, Bacillus thuringiensis. 4. Larvae from primed mothers showed greater survival than unprimed larvae, regardless of frass treatment; maternal treatment therefore showed a substantially greater contribution to larval priming than frass treatment. 5. Planned contrast tests to quantify the contributions of maternal and environmental matching revealed that maternal treatment mattered more for larvae exposed to primed, rather than unprimed, frass. This suggests that the effects of maternal egg provisioning may be exacerbated or mitigated by environmental factors. 6. Thus, although maternal egg provisioning plays a predominant role in producing the primed phenotype, environmental matching may matter for priming in some contexts.     

Phylogeny of Palaearctic Syrphidae (Diptera): evidence from larval stages

We estimated the phylogeny of Palaearctic Syrphidae using 187 larval morphological characters obtained from about 65% of the fauna (85 supraspecific taxa represented by 118 species) and based the analysis at the generic, level. The root of the syrphid tree was established from an outgroup consisting of other Aschizan families: the Platypezidae, Phoridae and Pipunculidae, with the tree rooted on the Lonchopteridae. The Syrphidae was the most derived Aschizan family. The Pipunculidae was the sister group to the Syrphidae. Eumerus was basal within Syrphidae. A trend exists towards increasing complexity of integumental folds and grooves across the Aschiza. In movement, the integument collapses along the line of these grooves. Grooves are evidence of muscles forming functional groups. Elaboration of independent groups of muscles appears to underlie much of the evolution of larval form within Aschiza. The basal feeding modes of syrphid larvae are mycophagy and phytophagy. Above these feeding modes, all remaining syiphids fall into one of two lineages comprising entomophages and saprophages, each of which has a single origin within the apparently polyphyletic Volucella. Major morphological innovation is associated with shifts between feeding modes; within feeding modes, change is gradual and tends towards increasing complexity. Change is mostly in structures associated with the mouthparts, thorax, anal segment and locomotory organs. Generic diagnoses with biological and taxonomic notes and a key to genera using larval characters are provided.     

Time series analysis of water quality data from Lake Ontario: implications for the measurement of water quality in large and small lakes

SUMMARY 1. The normal strategy of monitoring water quality is to sample such parameters as chlorophyll no more than weekly. A preferable strategy is to first define the natural periodicities in the water body and then to set up a sampling scheme that takes into account the natural scales of variance in physical, chemical and biological parameters. Failure to do so leads to aliased and biased estimates of means and variances and an inability to interpret the underlying physical and biological mechanisms.
2. The natural scales of variance vary with basin size. In lakes, physical and biological processes overlap at scales of from 1 to 15 days. Time series analysis of daily data from Lake Ontario and other lakes showed how the means and variances of the data sets were determined by the physical and biological processes in the water columns and displayed the fundamental lags in the systems. Even in small lakes and reservoirs, advective processes were of great importance. Advection became the dominant process in Lake Ontario. Time lags and advection made simple correlations of physical and biological parameters meaningless.
3. Decimation of the daily data sets revealed the statistical dangers of less frequent sampling. The desirable frequency of sampling was shown to be a function of the physics of the mixed layer, the turnover times of the nutrient pools, and the biological activity. Data from the three lakes graphically demonstrated the inadequacy of normal sampling frequencies.     

Inhibition of Clostridium botulinum type C by Bacteria Isolated from Mud

Clostridium botulinum type C was not detected in 54 samples of mud even after seeding them with a small number of spores of this organism. From 35 of these mud samples. 108 strains of bacteria were isolated which inhibited the growth of Cl. botulinum type C. strain FH 6513, but did not denature preformed toxin. These strains fell into three groups: Bacillus spp. (73%); Gram positive non-sporing rods (11%); and Gram positive cocci (16%). Seven strains of Bacillus spp. were further investigated and found to produce from two to five peptide antibiotics.