Development of Haemogregarina boueti in the toad Bufo regularis*

SYNOPSIS. Haemogregarina boueti França, 1910, was found to be the commonest blood parasite in the common toad, Bufo regularis Reuss, in Egypt. The rate of infection was about 30% (of 689 toads examined). In properly fixed blood films, the parasites were almost exclusively intraerythrocytic. Most characteristic was the encapsulated “elongate” form averaging 22.3 by 6 μ with a more-or-less central nucleus and a pointed, slightly bent, posterior end. Infected red cells were conspicuously hypertrophied and their nuclei were markedly displaced and frequently broken into 2-4 parts. Young and growing blood forms as well as two types of hepatic schizonts are described for the first time. Schizonts of the first type develop in hepatic cells, are 28–30 μ in diameter and produce numerous elongate oval merozoites about 8 × 2.2 μ radially arranged around a residual body about 10 μ in diameter. Schizonts of the second type start their growth in erythrocytes but later complete their development as free bodies in the liver sinusoids. When mature, they are 32–35 μ in diameter and produce a larger number of thin merozoites about 8 × 1.5 μ, surrounding a larger residual body about 19 μ in diameter.     

Haemogregarina faiyumensis n. sp. in the Toad Bufo regularis in Egypt*

SYNOPSIS. Haemogregarina faiyumensis n. sp., a parasite of toads, Bufo regularis, in Faiyuni Province, Egypt, U.A.R., is described. In a survey of 689 toads from various localities in Cairo, Giza and Faiyurn provinces, only 3 out of 13 toads from Kom O Shim near Faiyum were infected. This species, known only by blood forms (most probably gametocytes) of two different staining reactions, is 13-17 μ long and 4-5 μ wide, with an average of 15.5 × 4.5 μ. The nucleus is typically subcircular and 3-5 × 3–5 μ, with an average of 4.5 × 3.9 μ.     

Diaminopimelic Acid Synthesis in Cultures of an Escherichia coli Double Auxotroph: Effects of Cultural Conditions

The metabolic response to L-lysine of Escherichia coli ATCC 13002, a lysine-histidine double auxotroph, has been examined in a synthetic medium containing sucrose. In shaken cultures largest amounts of extracellular DAP were produced with an initial lysine concentration of 7·5 mg/1 and in static cultures of 2·5 mg/1. Considerably smaller amounts of DAP accumulated under stationary conditions. In cultures shaken for 20 and 43 h there was an overall decrease in the yields of DAP, expressed in terms of cell biomass and of sucrose consumed, as the initial concentration of lysine was increased from 0·75 mg/1 in steps up to 25 mg/1. The regulatory effect of lysine on DAP production was also observed when lysine was supplied to cultures at a constant rate employing diffusion capsules.     

Adaptive Finite Element Analysis of the Anisotropic Biphasic Theory of Tissue-Equivalent Mechanics

Abstract

The nonlinear partial differential equations of the anisotropic biphasic theory of tissue-equivalent mechanics are solved with axial symmetry by an adaptive finite element system. The adaptive procedure operates within a method-of-lines framework using finite elements in space and backward difference software in time. Spatial meshes are automatically refined, coarsened, and relocated in response to error indications and material deformation. Problems with arbitrarily complex two-dimensional regions may be addressed. With meshes graded in high-error regions, the adaptive solutions have fewer degrees of freedom than solutions with comparable accuracy obtained on fixed quasi-uniform meshes. The adaptive software is used to address problems involving an isometric cell traction assay, where a cylindrical tissue equivalent is adhered at its end to fixed circular platens; a prototypical bioartificial artery; and a novel configuration that is intended as an initial step in a study to determine bioartificial arteries having optimal collagen and cell concentrations.     

The role of lateral roots in bypass flow in rice (Oryza sativa L.)

Although an apoplastic pathway (the so‐called bypass flow) is implicated in the uptake of Na⁺ by rice growing in saline conditions, the point of entry of this flow into roots remains to be elucidated. We investigated the role of lateral roots in bypass flow using the tracer trisodium‐8‐hydroxy‐1,3,6‐pyrenetrisulphonic acid (PTS) and the rice cv. IR36. PTS was identified in the vascular tissue of lateral roots using both epifluorescence microscopy and confocal laser scanning microscopy. Cryo‐scanning electron microscopy and epifluorescence microscopy of sections stained with berberine‐aniline blue revealed that the exodermis is absent in the lateral roots. We conclude that PTS can move freely through the cortical layers of lateral roots, enter the stele and be transported to the shoot via the transpiration stream.     

Root Formation in Pea Cuttings

Auxin was applied to the upper part of the cuttings, which were both decapitated and disbudded on the same day. The applied auxin was removed by redecapitating the cuttings at different time intervals. In a second experiment, auxin was applied either to the upper or lower part of the decapitated and disbudded cuttings at different time intervals. In cuttings, which were redecapitated after 1 and 2 days, the root formation was reduced considerably. The redecapitation after 3 days had no adverse effect on the root formation. Cuttings treated with auxin at different time intervals showed a weaker root promotion on days 0 and 1 than on the subsequent days. The results emphasize the fact that auxin is active only during the first part of the root initiation phase. A continuous flow of auxin for a period of the first 3 days during the root initiation is of overriding importance. There appears to be at least two different stages of the root initiation phase, (ia) auxin active stage, and (ib) auxin inactive stage. The results also seem to indicate that some other factors, in addition to auxin, are active during the first stage of the root initiation phase.     

Prevalence and distribution of Borrelia and Babesia species in ticks feeding on dogs in the U.K.

Ticks were collected during March–July 2015 from dogs by veterinarians throughout the U.K. and used to estimate current prevalences and distributions of pathogens. DNA was extracted from 4750 ticks and subjected to polymerase chain reaction and sequence analysis to identify Borrelia burgdorferi sensu lato (Spirochaetales: Spirochaetaceae) and Babesia (Piroplasmida: Babesiidae) species. Of 4737 ticks [predominantly Ixodes ricinus Linneaus (Ixodida: Ixodidae)], B. burgdorferi s.l. was detected in 94 (2.0%). Four Borrelia genospecies were identified: Borrelia garinii (41.5%); Borrelia afzelli (31.9%); Borrelia burgdorferi sensu stricto (25.5%), and Borrelia spielmanii (1.1%). One Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae), collected from a dog with a history of travel outside the U.K., was positive for B. garinii. Seventy ticks (1.5%) were positive for Babesia spp. Of these, 84.3% were positive for Babesia venatorum, 10.0% for Babesia vulpes sp. nov., 2.9% for Babesia divergens/Babesia capreoli and 1.4% for Babesia microti. One isolate of Babesia canis was detected in a Dermacentor reticulatus (Ixodida: Ixodidae) tick collected from a dog that had recently travelled to France. Prevalences of B. burgdorferi s.l. and Babesia spp. did not differ significantly between different regions of the U.K. The results map the widespread distribution of B. burgdorferi s.l. and Babesia spp. in ticks in the U.K. and highlight the potential for the introduction and establishment of exotic ticks and tick‐borne pathogens.