Cytauxzoonosis in a giraffe (Giraffa camelopardalis (Linnaeus, 1758)) in Zululand

Cytauxzoonosis is reported for the first time in a giraffe [Giraffa camelopardalis (Linnaeus, 1758)] that died naturally of the disease. Both histiotropic and erythrocytic parasites were found. The animal was very anaemic and had marked haemoglobinuria. The most significant lesions were disseminated foci of haemorrhage and necrosis, especially in the liver, spleen and abomasum. Multiple haemorrhages also occurred on both pleura and peritoneum, within and on the entire gastro-intestinal tract, on the surface of the kidneys, subepicardially and in the urinary bladder. Very enlarged and even multinuclear cells heavily parasitized by schizonts were encountered in the lesions.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.

Flavonoids synthesized in cortical cells during nodule initiation are early developmental markers in white clover

Plant science

Do detached root‐cap cells influence bacteria associated with maize roots?

Abstract. A model rhizosphere has been used which consisted of detached root‐cap cells of maize in their surrounding root‐cap mucilage on the surface of Noble agar. These cells were co‐cultured for periods up to 32 d with eight different bacterial isolates from soil‐grown roots and surrounding soil and two laboratory cultures. Cap cells were unaffected by the bacteria. There were five different type‐specific responses of the bacteria in proximity to the cap cells. There were, strong growth inhibition (Rhizobium sp. and Escherichia coli), strong stimulation (Pseudomonas fluorescens, laboratory strain), mixed weak inhibition or stimulation (Pseudomonas fluorescens, field isolate), early inhibition followed by strong stimulation then spore formation (Bacillus spp.), no effect (Streptomyces sp. and Cytophaga sp.). It is concluded that detached root‐cap cells are actively involved in the establishment of characteristic rhizosphere bacterial microflora. Copyrigh

Leaf teeth, transpiration and the retrieval of apoplastic solutes in balsam poplar

The rapid flow of the transpiration stream through major veins to leaf teeth was followed in leaves of Populus balsamifera L., using the tracer sulphorhodamine G (SR), which probes for cells with H+‐extrusion pumps. The tracer accumulated quickly in the hydathodes of the teeth. It was shown by freeze‐substitution and anhydrous processing that SR was taken up by phloem parenchyma and epithem cells of the hydathode. When 14C‐labelled aspartate was fed to the leaves in the transpiration stream, it also was taken up most strongly by the same phloem parenchyma and epithem cells. It is proposed that one function of the hydathodes in leaf teeth is the retrieval of solutes from the transpiration stream. Copyrigh

The water status of the roots of soil‐grown maize in relation to the maturity of their xylem

The long delayed maturation of the late metaxylem of maize (Zea mays) roots imposes a high‐resistance barrier between the immature apices and the negative water potential of the leaves. These apices (20+ cm) bear strongly adhering soil sheaths to within 0.5 to 2 cm of the distal end. It was hypothesized that the sheathed immature apices should show less response to transpiration stress than bare regions. Measurements were made of the relative water content (RWC) of the sheathed and bare zones of the axile roots, both at different ages of the plant, and early and late in the day's transpiration. Sheathed roots maintained a steady RWC of about 83% irrespective of age or transpiration. Bare roots had RWCs of about 63% in the morning, but this fell to 55% in the afternoon. The first‐order branches on the bare roots in the morning had still lower values of RWC, near 50%. Plots of RWC against water potential were indistinguishable for the three root types. It is concluded that the immature apices are indeed relatively isolated from the fluctuating tensions in the stem xylem, and that these tensions reduce the water content of bare roots and their branches to low values. Copyrigh