Blood Parasites of Pekin Robins (Liothrix luteus)*

SYNOPSIS. The Pekin Robin (Liothrix luteus) is a species of babbler (Timaliidae) native to Southeast Asia. Except for Plasmodium tenue, a malaria parasite of the subgenus Novyella and much like P. vaughani, with which they are very commonly infected, these birds seem remarkably free of blood parasites. Of 152 birds examined, 4 harbored Leucocytozoon; no infections with Haemoproteus, trypanosomes, Atoxoplasma, or microfilariae were observed. Blood inoculation from 50 Pekin Robins into canaries revealed 3 P. relictum infections. Experimental inoculation of Pekin Robins with no evidence of prior malarial infection, with 6 species of Plasmodium, P. cathemerium, P. circumflexum, P. elongatum, P. octamerium, P. paranucleophilum, and P. vaughani, gave negative results; evidently the birds have a very unusual resistance to malaria (other than P. tenue). Their insusceptibility to P. vaughani is additional evidence of the validity of P. tenue as a species.     

Über bandartige Strukturen in den Chromozentren vonLupinus polyphyllus

In the nuclei ofLupinus polyphyllus strongly marked chromocentres occur. In electron micrographs of anther cell nuclei these chromocentres appear either as a homogeneous network or subdivided into two distinct regions, a network-like (NR) and a banded one (GR). In both a 100 Å fiber is the basic unit. The GR is composed of 4 to 6 parallely arranged electron dense bands (240–280 Å wide) and interbands (260–300 Å wide) of low electron density. They appear to correspond to a cylindrical structure with disc-like components and connective sections. These observations are discussed in relation to chromosome structure during interphase and mitosis.

Herrn Prof. Dr. L.Geitler zur Vollendung seines 80. Lebensjahres gewidmet.     

Retranslocation of boron in broccoli and lupin during early reproductive growth

The objective of the present study was to determine if boron (B) retranslocation depends on plant-B status and external-B supply. The stable ¹⁰B isotope was supplied to the root system of broccoli ( Brassica oleracea var. italica Plenck cv. Commander) and lupin ( Lupinus albus L. cv. Ultra) plants to provide a quantitative picture of B distribution during early reproductive development. Regardless of the B regime (i.e. continuous supply with luxury, sufficient or deficient B; transfer at inflorescence emergence from either a luxury- or sufficient-B supply to a deficient one) and whether ¹⁰B was acquired before or during inflorescence development, a significant proportion of the B recovered in broccoli florets and lupin fruit was ¹⁰B enriched. B acquired during inflorescence development was an important source of B for reproductive structures, but the relative importance of B acquired before and after inflorescence emergence appeared to be species dependent. The occurrence of B retranslocation was not dependent upon the induction of B deficiency. The concentrations of B in phloem exudates (0.38 to 0.03 mM) were 4- to 23-fold those in xylem sap, and more similar to the concentrations in the reproductive structures (0.86 to 0.07 mM) than those in source leaves (2.4 to 0.19 mM). The decreasing acropetal gradient of tissue-B concentrations with luxury-B supply declined dramatically or was reversed in plants grown with sufficient or deficient B. The data are consistent with B being a phloem-mobile element, and suggest that newly acquired B is particularly important during the early reproductive growth of plants.     

Variability of the Low Molecular Weight Globulin,Conglutin δ, Within Lupin Species

Conglutin δ, a 2S globulin, was purified and compared in six species or varieties of lupin seeds. A common pattern is suggested, present in all species, corresponding to a protein which could exist as a monomer or a dimer. The first form contains one subunit, from 11 to 16.2 kDa, according to the species. It possesses a quaternary structure closely related to conglutin δ1 and was previously described in the narrow-leaved lupin. The second form contains two similar subunits (23 to 26 kDa) and could be the conglutin δ2. These two subunits are associated even when SDS is used and are probably disulfide-linked subunits. Each subunit is composed of two disulfide-linked polypeptides. One is acidic with molecular weight from 14 to 17.3 kDa and the second is acidic to neutral, from 2.4 to 4.5 kDa. Three species (L. luteus, L. arboreus and L. pilosus) present a supplementary subunit, with different molecular weight and p than that previously described and which never associates in a dimer form. It has been purified in L. luteus. When native, this protein is oligomeric. The subunit of 12 kDa in this species is composed of a polypeptide of 9 kDa (pl 4.5) disulfide-linked to one of 3 kDa (pl 6.5). This supplementary protein remains partly associated with the first in the yellow lupin (L. luteus). It probably corresponds to a new protein, different from conglutin δ.     

The effect of soil freezing on the survial of winter-sown white lupins (Lupinus albus L.)

Specially constructed soil-freezing growth boxes were used to study the effects of the intensity and duration of soil freezing on root injury and the survival of white lupin seedlings of different ages under controlled conditions. The extent of root damage depended on both the intensity of soil freezing and the stage of seedling development (measured as the extent of lignification of the central stele of the primary root). Seedlings whose secondary root development was well advanced, and in which the endodermis was completely lignified, survived intense soil freezing intact. Young seedlings with weakly lignified roots were damaged by moderate soil freezing (> 5 days at ?1°C) and killed by more intense freezing (5 days at ?2°C). The extent of root development and ligmfkation was correlated with the number of leaf primordia produced at the shoot apex so that the susceptibility to soil freezing damage could be accurately predicted by a simple physiological/leaf production model.     

Acid phosphatase activity in phosphorus-deficient white lupin roots

White lupin ( Lupinus albus L.) develops proteoid roots when grown in phosphorus (P)-deficient conditions. These short, lateral, densely clustered roots are adapted to increase P availability. Previous studies from our laboratory have shown proteoid roots have higher rates of non-photosynthetic carbon fixation than normal roots and altered metabolism to support organic acid exudation, which serves to solubilize P in the rhizosphere. The present work indicates that proteoid roots possess additional adaptations for increasing P availability and possibly for conserving P in the plant. Roots from P-deficient (–P) plants had significantly greater acid phosphatase activity in both root extracts and root exudates than comparable samples from P-sufficient (+P) plants beginning 10 d after emergence. The increase in activity in –P plants was most pronounced in the proteoid regions. In contrast, no induction of phytase activity was found in –P plants compared to +P plants. The number of proteoid roots present was not affected by the source of phosphorus supplied, whether organic or inorganic forms. Adding molybdate to the roots increased the number of proteoid roots in plants supplied with organic P, but not inorganic P. Increased acid phosphatase activity was detected in root exudates in the presence of organic P sources. Native-polyacrylamide gel electrophoresis demonstrated that under P-deficient conditions, a unique isoform of acid phosphatase was induced between 10 and 12 d after emergence. This isoform was found not only within the root, but it comprised the major form exuded from proteoid roots of –P plants. The fact that exudation of proteoid-root-specific acid phosphatase coincides with proteoid root development and increased exudation of organic acids indicates that white lupin has several coordinated adaptive strategies to P-deficient conditions.     

Exocellular (glyco)proteins of Lupinus albus plants and suspension-cultured cells

Plant species from genus Lupinus are among the oldest known legumes, and various aspects of their biology are considerably different from those commonly observed within Leguminosae. To study this issue in more detail, a suspension culture of Lupinus albus cells was developed, and the glycosylation patterns of exocellular proteins analysed. N-linked oligosaccharide side-chains were detected with two lectins: concanavalin A (ConA) and wheat germ agglutinin (WGA) used with respective anti-lectin antibodies, while O-linked arabinosylated side-chains of (hydroxy)proline-rich glycoproteins were identified with anti-(42 kDa French bean chitin-binding protein) antibodies. The obtained data were compared with analogous ones for exocellular (glyco)proteins from suspension-cultured Phaseolus vulgaris cells and from various tissues of L. albus plants. Major species-specific differences between exocellular (glyco)proteins from lupin and bean cells were identified. Similarly, developmentally regulated glycosylation changes following transition from organised plant tissue to dedifferentiated suspension-cultured lupin cells were detected and analysed.     

Seasonal growth of tree lupins (Lupinus arboreus) and the effect of defoliation on leaf production

The growth of tree lupins was investigated in two experiments. In the first, two ages of plant, 4-wk-old seedlings and 1-year-old plants, were transplanted into a ryegrass sward in an upland environment. Growth, in terms of leaf production, branching and stem elongation, was measured over two successive growing seasons. Plant dry matter and nutrient contents were determined at the beginning and end of each growing season. In the first summer, the rate of production of new leaves on the main stem of seedling plants averaged 1.8 leaves per wk and main stem length increased from 5 to 67 cm. On older plants, where floral apices had been initiated on main and primary stems, there was a 3–10 fold increase in secondary branch length. In the second season, there was no effect of plant age on rates of leaf appearance or stem extension; dry matter production was higher than in the first season. In the second experiment, the effect of removal of 0%, 50% or 100% of fully expanded leaves on the subsequent growth of 23-wk-old plants was investigated. During the 7-wk growth period, defoliation promoted the rate of production of mature leaves, and area and dry weight of new laminae were slightly higher in defoliated plants. Defoliation did not affect the concentrations of N, P or K in the new laminae, but P and K concentrations in petioles of defoliated plants were significantly higher than those in intact plants. The results from the experiments are discussed in relation to the potential use of tree lupins as nurse species and biomass crops in hill and upland environments of the UK.     

Estimation of dormant Micrococcus luteus cells by penicillin lysis and by resuscitation in cell-free spent culture medium at high dilution

Abstract Micrococcus luteus starved for 2–7 months in spent medium following growth to stationary phase in batch culture exhibited a culturability (as estimated by direct plating on nutrient agar plates) of < 0.001%. However, following a lag, some 70% of the cells could be lysed upon inoculation into and cultivation in fresh lactate minimal medium containing penicillin, showing the capability of a significant portion of the cells at least to enlarge (and thus potentially to resuscitate). When the viable cell count was estimated using the most probable number method, by incubation of high dilutions of starved cells in liquid growth media, the number of culturable or resuscitable cells was very low, and little different from the viable cell count as assessed by plating on solid media. However, the apparent viability of these populations evidenced with the most probable number method was 1000–100 000-fold greater when samples were diluted into liquid media containing supernatants taken from the stationary phase of batch cultures of the organism, suggesting that viable cells can produce a factor which stimulates the resuscitation of dormant cells. Both approaches show, under conditions in which the growth of a limited number of viable cells during resuscitation is excluded, that a significant portion of the apparently non-viable cell population in an extended stationary phase is dormant, and not dead.