bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytokinin oxidase or dehydrogenase?
Authors: Galuszka Petr , Frébort Ivo , Šebela Marek , Sauer Pavel , Jacobsen Susanne , Peč Pavel
Published: September 2003

An enzyme degrading cytokinins with isoprenoid side chain, previously named cytokinin oxidase, was purified to near homogeneity from wheat and barley grains. New techniques were developed for the enzyme activity assay and staining on native electrophoretic gels to identify the protein. The purified wheat enzyme is a monomer 60 kDa, its N‐terminal amino‐acid sequence shows similarity to hypothetical cytokinin oxidase genes from Arabidopsis thaliana, but not to the enzyme from maize. N6‐isopentenyl‐2‐(2‐hydroxyethylamino)‐9‐methyladenine is the best substrate from all the cytokinins tested. Interestingly, oxygen was not required and hydrogen peroxide not produced during the catalytic reaction, so the enzyme behaves as a dehydrogenase rather than an oxidase. This was confirmed by the ability of the enzyme to transfer electrons to artificial electron acceptors, such as phenazine methosulfate and 2,6‐dichlorophenol‐indophenol. 2,3‐Dimethoxy‐5‐methyl‐1,4‐benzoquinone, a precursor of the naturally occurring electron acceptor ubiquinone, readily interacts with the enzyme in micromolar concentrations. Typical flavoenzyme inhibitors such as acriflavine and diphenyleneiodonium inhibited this enzyme activity. Presence of the flavin cofactor in the enzyme was confirmed by differential pulse polarography and by measuring the fluorescence emission spectrum. Possible existence of a second redox centre is discussed.
New pathway of amine oxidation respiratory chain of Paracoccus denitrificans IFO 12442
Authors: Takagi Kazuyoshi , Yamamoto Keiko , Kano Kenji , Ikeda Tokuji
Published: September 2003

The physiological electron acceptor of quinohemoprotein amine dehydrogenase (QH‐AmDH) from Paracoccus denitrificans IFO 12442 was identified by biochemical and electrochemical methods. Of three types of heme c‐containing proteins purified together with QH‐AmDH from the periplasm of n‐butylamine‐grown cells, only constitutive cytochrome c‐550 was reduced by the addition of QH‐AmDH and n‐butylamine. Reconstitution of the respiratory chain revealed that cytochrome c‐550 mediates the electron transfer from QH‐AmDH to the terminal oxidase. This is a new pathway of the amine oxidation respiratory chain of P. denitrificans.
The low‐molecular‐mass subunit of the cell wall channel of the Gram‐positive Corynebacterium glutamicum
Authors: Lichtinger Thomas , Rieß Franziska G. , Burkovski Andreas , Engelbrecht Fredi , Hesse Dörte , Kratzin Hartmut D. , Krämer Reinhard , Benz Roland
Published: September 2003

The 5‐kDa protein PorA of the Gram‐positive bacterium Corynebacterium glutamicum is the subunit of the cell wall channel. Antibodies raised against PorA specifically detected the protein on the cell surface. PorA was sequenced using Edman degradation and a gas phase sequencer. The primary sequence was used to create degenerate oligonucleotide primers. The gene of the channel‐forming protein and its flanking regions were obtained by PCR followed by inverse PCR. The gene porA comprises 138 bp and encodes a 45‐amino‐acid‐long acidic polypeptide with an excess of four negatively charged amino acids in agreement with the high cation selectivity of the PorA cell wall channel. PorA does not contain an N‐terminal extension. A ribosomal‐binding site was recognized 6 bp before the start codon ATG of porA. It codes for the smallest subunit of a membrane channel known so far and for the first cell wall channel protein of a corynebacterium. Southern blots demonstrated that only the chromosomes of corynebacteria contain homologous sequences to porA; no hybridization could be detected with DNA from other mycolata.
Crystal structures of bovine β‐lactoglobulin in the orthorhombic space group C2221
Authors: Oliveira Kesley M. G. , Valente‐Mesquita Vera L. , Botelho Michelle M. , Sawyer Lindsay , Ferreira Sérgio T. , Polikarpov Igor
Published: September 2003

The crystal structures of β‐lactoglobulin genetic variants A and B have been determined in the orthorhombic space group C2221 (lattice Y) by X‐ray diffraction at 2.0 Å and 1.95 Å resolution, respectively. The structural comparison shows that both variants exhibit the open conformation of the EF loop at the pH of crystallization (pH 7.9), in contrast to what has been reported for the same genetic variants at pH 7.1 in the trigonal space group P3221 (lattice Z) [Qin, B.Y., Bewley, M.C., Creamer, L.K., Baker, E.N. & Jameson, G.B. (1999) Protein Sci.8, 75–83]. Furthermore, it was found that the stereochemical environment of Tyr42 changes significantly with pH variation between pH 7 and pH 8. This may provide a structural explanation for an as yet unexplained feature of the Tanford transition, namely the increase in exposure of a tyrosine residue.
Effect of Non‐Steroidal Aromatase Inhibitor on Blood Plasma Ovarian Steroid and Thyroid Hormones in Laying Hen (Gallus domesticus)
Authors: Sechman A. , Rząsa J. , Paczoska‐Eliasiewicz H.
Published: September 2003

HyLine Brown laying hens at 30 weeks of age were treated twice daily with Fadrozole, a non‐steroidal aromatase inhibitor (AI; 1 mg/kg body weight; i.m.) for six consecutive days; control hens received saline. Blood was collected every day 0.5 h after oviposition, i.e. just before AI treatment. Ovarian steroids: progesterone (P4), testosterone (T) and estradiol (E2), and iodothyronines: thyroxine (T4), triiodothyronine (T3) and reverse‐triiodothyronine (rT3) were measured in blood plasma by radioimmunoassay methods. In AI‐treated hens a gradual delay in oviposition time was observed. AI significantly decreased P4 and E2 levels, maximally by 43% on day 4 and by 74% on day 5, respectively, and elevated T level, maximally by 248% on day 4. Simultaneously, the increases in T4 and T3 levels with no changes in rT3 levels were observed. The maximal effect of AI on T4 and T3 levels was found on day 4 (60% increase) and day 5 (312% increase), respectively. Moreover, statistically significant, negative coefficient of correlation between E2 and T3 (r = −0.51), and positive coefficient of correlation between T and T3 (r = 0.42) in AI‐treated hens were found. The results obtained indicate that in mature laying hens there is a strong relationship between ovarian steroids and thyroid hormones, and suppression of E2 synthesis not only disrupts ovarian function but also affects the activity of the thyroid gland and peripheral metabolism of thyroid hormones.
Pathological Effects of Formalin (37% Formaldehyde) Mixed in Feed or Administered into the Crops of White Leghorn Cockerels
Authors: Khan M. Z. , Ali Z. , Muhammad G. , Khan A. , Mahmood F.
Published: September 2003

This study compared the adverse effects of formalin administered by two different methods. Formalin mixed with the feed (2.5, 5.0 and 10 ml/kg) was given to 10‐week‐old White Leghorn cockerels for a period of 8 weeks. Simultaneously in other groups, a 3% solution of formalin was administered into the crops (5, 10, 15 and 20 ml/bird/day). Total amount of formalin utilized during the experiment in the feed of individual bird of groups given 2.5, 5 and 10 ml/kg was 6.25, 3.9 and 1.6% higher than those administered 5, 10 and 20 ml of 3% formalin into crop, respectively. Body mass and feed intake in all feed‐mixed groups and those given 5 and 10 ml formalin (3%) into the crop were not significantly different from control. Administration of 15 and 20 ml formalin (3%) into crop resulted in depression, delayed onset of crowing, significantly decreased feed intake, lower body mass, decreased mass and volume of testes, ulceration in crops, sloughing of mucosa and petechial haemorrhages in proventriculus. All the groups given formalin had significantly smaller diameters of seminiferous tubules. Kidneys of the birds administered formalin into crop exhibited pyknotic nuclei of epithelial cells in proximal tubules. Non‐significant differences in different parameters and lesser degree of pathological changes in birds given formalin‐mixed feed than their corresponding crop‐administered groups suggested that formalin present in the feed had partially evaporated. Therefore, birds ingested less amount of formalin than that originally mixed in the feed.
Levels of Retinol and Retinyl Esters in Plasma and Urine of Dogs with Urolithiasis
Authors: Raila J. , Forterre S. , Schweigert F. J.
Published: September 2003

Vitamin A (VA) deficiency and Tamm‐Horsfall glycoprotein (THP), a protein that binds retinol and retinyl esters in canine urine, might be involved in the pathogenesis of urolithiasis in dogs. In the present study, we assessed levels of retinol, retinyl esters, retinol‐binding protein (RBP) and THP in plasma and urine of dogs with a history of urolithiasis (n = 25) compared with clinically healthy controls (n = 18). Plasma retinol concentrations were higher in dogs with uroliths of struvit (P < 0.01), calcium oxalate (P < 0.05), urate (P < 0.01) and cysteine, but there were no differences in the concentrations of plasma RBP and retinyl esters. Excretion of urinary retinol and retinyl esters were tentatively, but not significantly higher in the stone‐forming groups, which was accompanied by increased levels of urinary RBP (P < 0.01) and lower excretions in THP (P < 0.01). The results show that VA deficiency may be excluded as a potential cause for canine urolithiasis. However, the occurrence of RBP and a concomitant reduction of THP in urine indicates a disturbed kidney function as cause or consequence of stone formation in dogs.
Metastatic Gastric Adenocarcinoma and Diffuse Hyperplastic Gastritis Resembling Human Menétrier's Disease in a Camel (Camelus ferus bactrianus)
Authors: Kühn N. , Gröne A. , Pagan O. , Bacciarini L. N.
Published: September 2003

A captive 16‐year‐old male camel (Camelus ferus bactrianus) was euthanized after a prolonged period of inappetence leading to cachexia. At necropsy, there was a 7 cm large, tan, firm, well‐demarcated nodule in the tunica muscularis and serosa of the distal region of C3. Histologically, a gastric adenocarcinoma was diagnosed. Numerous metastases were found in the liver and the hepatic lymph nodes, in the wall of the portal vein and the aorta, in the lung, heart, and pleura parietalis. Osseous metaplasia was found within the pleural and aortic metastases.

In the mucosa of the glandular region of the C3 compartment a diffuse marked hypertrophy of rugae resembling cerebral convolutions was observed. The lesion was characterized by glandular hyperplasia and stromal inflammation and oedema. These changes closely resembled Menétrier's disease described in humans.

To our knowledge, this is the first report of concomitant metastatic gastric adenocarcinoma and gastric hyperplasia in a camel.
Hypocholesterolaemia in Dogs with Dominance Aggression
Authors: Pentürk S. , Yalçin E.
Published: September 2003

Serum lipids and lipoprotein concentrations have been associated with dominance aggression in humans. The aim of this study was to investigate the link between serum lipids, including cholesterol, triglyceride, high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C), total cholesterol (TC) to HDL‐C ratio and dominance aggression in dogs. Levels of serum TC, triglyceride and HDL‐C were significantly lower in dogs with dominance aggression compared with non‐aggressive dogs (P < 0.001). These results suggest that a relationship exists between serum lipid profile and dominance aggression in dogs, and hypocholesterolaemia exists in dogs with dominance aggression.
Changes in the Level of Endogenous Leptin, FSH, 17β‐Oestradiol and Metabolites during Lupin‐induced Increase in Ovulation Rate in Ewes
Authors: Kosior‐Korzecka U. , Bobowiec R.
Published: September 2003

The aim of the study was to determine the changes in the plasma concentration of leptin during lupin feeding‐induced increase in the ovulation rate (OR) in ewes. Additionally, alterations in the plasma level of glycogenic amino acids and glucose (as the factors influencing leptin secretion) and the levels of follicle‐stimulating hormone (FSH) and 17β‐oestradiol (E‐2) (as the hormones regulated by leptin and engaged in recruitment, selection and development of ovulatory follicles) were analysed. Ninety‐six female Polish Lowland Sheep were used. All ewes were cyclic and synchronized with PGF2α. The ewes were divided into two groups: control (n = 48), fed only with hay, and experimental (n = 48), received additionally lupin (Lupinus angustifolius) grain as a high‐protein and a high‐energy supplement. They were given lupin from the second to 13th day of the oestrous cycle at increasing doses (150–750 g/day per ewe). On the 11th day of cycle blood samples for analysis of hormones, amino acids and total glucose concentration, were collected from the jugular vein. OR was determined by laparoscopy of ovaries on the sixth day of the following oestrous cycle. Mean OR of ewes supplemented with lupin grain (1.687 ± 0.463) was 30.67% higher than that of control (1.291 ± 0.454). In spite of the unchanged body mass, a significant increase (P ≤ 0.05) in mean concentration of plasma leptin in the experimental ewes [2.17 ± 0.15 ng/ml human equivalent (HE)] was found in comparison with control (1.42 ± 0.12 ng/ml HE). A significantly (P ≤ 0.05) higher plasma FSH level in the ewes fed lupin (105.21 ± 5.87 ng/ml) compared with those fed hay (67.88 ± 6.03 ng/ml) was also found. However, plasma level of E‐2 decreased after lupin feeding. Moreover, in the ewes fed lupin the plasma concentrations of glucose and nine glycogenic amino acids (Gly, Ala, Val, Met, Leu, Ile, Tyr, Phe and Arg) were increased. It can be concluded that lupin feeding exerts the stimulatory effect on the OR in Polish Lowland Sheep. The increase in OR is connected with significantly higher plasma leptin level and coincident with rise in FSH, glycogenic amino acids and glucose concentration. In contrast, the level of plasma E‐2 was significantly decreased in lupin‐fed ewes.
Spontaneous Uterine Fibroleiomyoma in a Captive Cheetah
Authors: Walzer C. , Kübber‐Heiss A. , Bauder B.
Published: September 2003

Information on uterine neoplasia in felids and more so in non‐domestic felids is sparse. In non‐domestic felids, this may be due to the small sample size. A uterine fibroleiomyoma is described in a 17‐year‐old captive cheetah. The multicentric nodular tumour masses were situated in the myometrium, were well demarcated, non‐encapsulated and did not show infiltrative growth. Between the neoplastic cells, numerous of varying width, and irregularly braided bundles and whorls of collagen and reticular fibres were demonstrated. Immunohistochemical examinations revealed positive reactions for both desmin, the marker for smooth and skeletal muscle cells, and vimentin, the marker for fibrocyte‐derived cells.
Lactoferrin and Citrate Concentrations at Drying‐off and During Early Mammary Involution of Dairy Cows
Authors: Kutila T. , Pyörälä S. , Kaartinen L. , Isomäki R. , Vahtola K. , Myllykoski L. , Saloniemi H.
Published: September 2003

Quarter milk samples were taken from 48 clinically healthy, pregnant Finnish Ayrshire and Friesian dairy cows at the last milking before drying‐off, and 2 and 6 days later to determine the lactoferrin and citrate concentrations in the udder secretion. The mean lactoferrin concentration in the milk increased from 5.29 mg ml−1 on the last day of drying‐off process to 8.09 and 11.26 mg ml−1, 2 and 6 days later, respectively. Citrate concentration decreased from 1.85 mg ml−1 to 1.54 and 1.09 mg ml−1, respectively. Median molar ratio (citrate to native‐Lf) decreased from 153 to 86 and further to 44. Lf and citrate concentrations in milk varied greatly among cows. Sampling time had a statistically significant effect on lactoferrin and citrate concentrations in milk while the breed and the parity of the cows had no effect on either of these variables.
Leiomyosarcoma of the Kidney in a Dog
Authors: Sato T. , Aoki K. , Shibuya H. , Machida T. , Watari T.
Published: September 2003

A leiomyosarcoma that occurred in the right kidney of a dog (7‐year‐old female Labrador retriever) was studied pathologically. On histological examination, tumour cells were spindle‐shaped, the cell density was high, and complex fasciculated tumour cells showing longitudinal and transverse cross‐sections were observed. Both ends of the nuclei were rounded, the nucleoli were clear and many images of nuclear division were observed. Immunohistochemically, tumour cells reacted intensely with anti‐vimentin antibody and anti‐actin smooth muscle antibody, and mildly with anti‐desmin antibody. On electron microscopy, the nuclei of tumour cells were rounded at both ends and elongated elliptically, and a large number of microfibrils with focal density and dense patches were observed in the cytoplasm. This is a case report of a very rare leiomyosarcoma of the dog kidney.
The potential effects of repeated outbreaks of phocine distemper among harbour seals: a response to Harding et al. (2002)
Authors: Lonergan Mike , Harwood John
Published: September 2003

In 2002 phocine distemper virus (PDV) reappeared in the European harbour seal (Phoca vitulina) population. This outbreak seems to have followed a similar pattern to the 1988 one which killed almost 60% of individuals in most localities. Harding et al. (2002) suggested that there is a relatively high (18%) risk that recurrent outbreaks of PDV could reduce the European harbour seal population by 90%. We show that incorporating the effects of observation error during population surveys and of the long‐term immunity of survivors of morbillivirus outbreaks indicate a much lower level of risk (<1%). This suggests that, while the immediate effects of the disease are dramatic, it is unlikely that recurrent epidemics will pose serious conservation problems for this species under current conditions.
Ecological interpretations of the mid‐domain effect
Authors: Grytnes John Arvid
Published: September 2003

The suggestion that spatial gradients in species richness are influenced by geometric constraints resulting in the mid‐domain effect has been investigated by null models. The technical aspects of making such null models are well explored, but the implicit ecological assumptions behind these models are less explored. Four ecological models that all assume that species ranges are constrained by hard boundaries are made: evolutionary model, source‐sink model, dynamic‐environment model, and range‐size model. These models give different predictions that make it possible to separate the models from each other, and from a model that assumes that hard boundaries are not important.
Testing intraguild predation theory in a field system: does numerical dominance shift along a gradient of productivity?
Authors: Borer Elizabeth T. , Briggs Cheryl J. , Murdoch William W. , Swarbrick Susan L.
Published: September 2003

Although ecological theory exists to predict dynamics in communities with intraguild predation (IGP), few empirical tests have examined this theory. IGP theory, in particular, predicts that when two competitors interact via IGP, with increasing resource productivity: (1) the IG predator will increase in abundance as the IG prey declines, and (2) increasing dominance of the IG predator will cause resource density to increase. Here, we provide a first test of these predictions in a field community consisting of a scale insect and its two specialist parasitoids, Aphytis melinus (the IG predator) and Encarsia perniciosi (the IG prey). The shared resource, California red scale, is a pest of citrus, and its productivity varies across a threefold range among citrus cultivars. We examined both absolute and relative densities of parasitoids along this natural gradient of scale productivity in three citrus cultivars (orange, grapefruit and lemon). Although both parasitoid species were found in all three cultivars, their abundances reflected those predicted by IGP theory: the IG prey species dominated at low productivity and the IG predator dominated at high productivity. This relationship was caused by an increase in Aphytis density with productivity. In addition, the density of scale increased with the dominance of the IG predator. These results from a field system demonstrate the important dynamic outcomes for food webs with IGP.
Diversity reduces invasibility in experimental plant communities: the role of plant species
Authors: van Ruijven Jasper , De Deyn Gerlinde B. , Berendse Frank
Published: September 2003

Several studies have presented experimental evidence that diversity reduces invasibility in grassland communities. The interpretation of these results has been disputed recently and it was proposed that sampling effects were responsible for the observed decrease of invasibility with diversity. The experiments performed to date were not designed to adequately separate sampling from diversity effects. Using the establishment of native plant species in experimental plant communities as a model of invasibility, we show that the number of invaders decreased with increasing diversity. When the presence of particular species is included, their effects are dominant.Centaurea jaceashowed a strong effect at low diversity, whereasLeucanthemum vulgareshowed a very strong negative impact at each diversity level. The negative effect of the latter might be related to root‐feeding nematodes that showed far higher abundance in plots withLeucanthemum. However, diversity remained a significant factor in determining the number of invading species and the numbers of an abundant invader.
The species–area relationship derived from species‐specific incidence functions
Authors: Ovaskainen Otso , Hanski Ilkka
Published: September 2003

The species–area relationship (SAR), describing the increase in species number (S) with increasing area (A), is one of the most robust patterns in ecology with great significance for conservation. The SAR is generally formulated as a power function, S = kAz, although the semilogarithmic form S = a + b log A has often been used by botanists. Here we unite the two forms by deriving SARs from the incidence functions of the species that make up the community. We show how the decisive scaling parameters z and b relate to the properties of individual species, and highlight why the biological interpretation of SARs has been so enigmatic.
Species richness, endemism, and abundance patterns: tests of two fractal models in a serpentine grassland
Authors: Green Jessica L. , Harte John , Ostling Annette
Published: September 2003

Although scaling relationships that characterize fractal species distributions offer an exciting potential for unification in biogeography, empirical support for fractal theory remains the subject of debate. We synthesize and test multiple predictions of two interrelated fractal models and a null model of random placement using Californian serpentine grassland data describing the spatial location of over 37 000 individually identified plants. The endemics–area relationship and species‐abundance distribution recently derived from a community‐level fractal property performed poorly because of an inaccurate assumption of homogeneity among species. In contrast, a species‐level fractal model that incorporates species‐level differences predicted abundances well, but systematically overestimated endemism and predicted a species–area relationship that violated the observed power law. These findings indicate that in order to make predictions based on the existence of a power‐law species–area relationship, ecologists need a unifying theory of how the community‐level fractal property arises in the presence of species‐level distributional differences.
Biodiversity and species interactions: extending Lotka–Volterra community theory
Authors: Wilson W. G. , Lundberg P. , Vázquez D. P. , Shurin J. B. , Smith M. D. , Langford W. , Gross K. L. , Mittelbach G. G.
Published: September 2003

A new analysis of the nearly century‐old Lotka–Volterra theory allows us to link species interactions to biodiversity patterns, including: species abundance distributions, estimates of total community size, patterns of community invasibility, and predicted responses to disturbance. Based on a few restrictive assumptions about species interactions, our calculations require only that the community is sufficiently large to allow a mean‐field approximation. We develop this analysis to show how an initial assemblage of species with varying interaction strengths is predicted to sort out into the final community based on the species’ predicted target densities. The sorting process yields predictions of covarying patterns of species abundance, community size, and species interaction strengths. These predictions can be tested using enrichment experiments, examination of latitudinal and productivity gradients, and features of community assembly.
Experimental evolution of dispersal in spatiotemporally variable microcosms
Authors: Friedenberg Nicholas A.
Published: September 2003

The world is an uncertain place. Individuals’ fates vary from place to place and from time to time. Natural selection in unpredictable environments should favour individuals that hedge their bets by dispersing offspring. I confirm this basic prediction usingCaenorhabditis elegansin experimental microcosms. My results agree with evolutionary models and correlations found previously between habitat stability and individual dispersal propensity in nature. However, I also find that environmental variation that triggers conditional dispersal behaviour may not impose selection on baseline dispersal rates. These findings imply that an increased rate of disturbance in natural systems has the potential to cause an evolutionary response in the life history of impacted organisms.
Accumulation of soluble carbohydrates, trehalase and sucrose synthase in effective (Fix+) and ineffective (Fix - ) nodules of soybean cultivars that differentially nodulate with Bradyrhizobium japonicum
Authors: Xie Zhi-Ping , Staehelin Christian , Broughton William J. , Wiemken Andres , Boller Thomas , Müller Joachim
Published: September 2003

Roots of soybeans have the ability to form symbioses with nitrogen-fixing rhizobial bacteria to form nitrogen-fixing (Fix+) nodules, thus allowing the plant to grow in the absence of mineral nitrogen. Several soybean cultivars from China nodulated normally with Bradyrhizobium japonicum USDA110 spc4, but developed only a few nodules with 61-A-101, another B. japonicum strain. When soybeans were infected with Rhizobium sp. NGR234, ineffective (Fix–) nodules that do not fix nitrogen were formed. Plants infected with NGRΩnodD2, a mutant strain overproducing lipo-chitooligosaccharidic nodulation signals (Nod factors), showed significantly higher numbers of ineffective nodules. Nodules from the different plant–microsymbiont combinations were characterized with respect to their accumulation of soluble carbohydrates and their induction of trehalase and sucrose synthase. These two plant enzymes are known to be nodule-stimulated proteins. Pool sizes of soluble carbohydrates in nodules showed strain-specific alterations in sucrose and trehalose, whereas myo-inositol and pinitol were affected in a more cultivar-specific way. Immunoblots with nodulin-specific antiserum indicated that sucrose synthase is induced in Fix+ nodules, but undetectable in Fix– nodules, indicating a strain-specific induction profile. Trehalase activity in nodules showed a similar strain-specific induction profile. High enzyme activity was measured for nodules harboring the Bradyrhizobium strains, whereas ineffective nodules containing NGR234 exhibited activities in the range of uninfected roots. Nodules induced by NGRΩnodD2 showed increased trehalase activity. A similar induction of trehalase was observed when uninfected roots were treated with Nod factors purified from NGR234. The data obtained are discussed in the context of carbohydrate allocation in nodules and the question of how rhizobial bacteria influence the carbohydrate metabolism of their host plant is addressed.
Genetic variation for adventitious rooting in response to low phosphorus availability: potential utility for phosphorusacquisition from stratified soils
Authors: Miller Carter R. , Ochoa Ivan , Nielsen Kai L. , Beck Douglas , Lynch Jonathan P.
Published: September 2003

We hypothesized that adventitious roots may improve crop adaptation to low-phosphorus soils by enhancing topsoil foraging. In a tropical field study, phosphorus stress stimulated adventitious rooting in two phosphorus-efficient genotypes of common bean (Phaseolus vulgaris L.) but not in two phosphorus-inefficient genotypes. Although phosphorus availability had no consistent effects on the length or biomass of whole root systems, it had differential effects on adventitious, basal, and taproots within root systems in a genotype-dependent manner, resulting in increased allocation to adventitious roots in efficient genotypes. Adventitious roots had greater length per unit biomass than other root types, especially under phosphorus stress. Adventitious roots had less construction cost than basal roots, despite having similar tissue nitrogen content. Phosphorus stress reduced lateral root density, and adventitious roots had less lateral root density than basal roots. Lateral roots formed further from the root tip in adventitious roots compared with basal roots, especially under phosphorus stress. Field results were confirmed in controlled environments in solid and liquid media. Stimulation of adventitious rooting by phosphorus stress tended to be greater in wild genotypes than in cultivated genotypes. We propose that adventitious rooting is a useful adaptation to low phosphorus availability, because adventitious roots explore topsoil horizons more efficiently than other root types.
A quantitative study of lateral branching in petunia
Authors: Snowden Kimberley C. , Napoli Carolyn A.
Published: September 2003

The monopodial shoot axis of petunia (Petunia hybrida Vilm) has two different patterns of branch development. Basal lateral branching develops acropetally and is limited to a discrete number of nodes that correlate with the late rosette phase of growth (Zone II). Two zones of suppressed buds immediately precede and follow this zone of branching. Apical branching occurs in response to flowering, develops in a basipetal direction, and is restricted to the distal-most nodes on the monopodial axis. When grown under a short-day regime, an extension to the basal branching zone occurs, and growth of the main shoot axis is retarded. The sym1 mutant has an overall decrease in basal lateral branching compared with wild type whereas the three dad mutants have increased basal branching. The dad1-1 and dad2-1 mutants have no initial zone of suppressed branching whereas the dad3 mutant has a similar Zone II to wild type, but with a greater potential to form branches within this zone. The dad1-1 mutant exhibits delayed flowering, but the dad1-1 sym1 double mutant flowers at a similar node number to wild-type and branching is similar to dad1-1 indicating that these two aspects of the mutant dad1-1 phenotype are independent.
Relationship of indoleacetic acid and tryptophan to dormancy and preharvest sprouting of wheat
Authors: Ramaih Shashi , Guedira Mohammed , Paulsen Gary M.
Published: September 2003

Preharvest sprouting of wheat (Triticum aestivum L.) involves several plant hormones, but a role for indoleacetic acid (IAA) and its precursor, tryptophan, has not been demonstrated. Our objectives were to determine the roles of IAA, tryptophan, and related compounds in germination of cultivars that differed in susceptibility to preharvest sprouting. L-Tryptophan strongly inhibited germination of embryos excised from caryopses that were highly dormant at harvest but not of embryos from caryopses that had little innate dormancy. The embryos responded similarly to indoleacetaldehyde, IAA, and synthetic auxins, suggesting that tryptophan functioned as a precursor of IAA. Indoleacetaldehyde oxidase inhibitors alleviated the adverse effects of tryptophan and indoleacetaldehyde, and an auxin antagonist decreased the inhibitory action of tryptophan and IAA on embryos from dormant caryopses, further suggesting that IAA was involved. Changes in sensitivity to IAA during afterripening also supported a role for auxin in dormancy. Embryos from caryopses that were highly dormant at harvest gradually lost sensitivity to IAA during afterripening, whereas intact caryopses were insensitive to IAA. The results implicated IAA in dormancy of wheat caryopses and indicated that the auxin might complement the role of abscisic acid in germination. The importance of using dormant caryopses and arresting afterripening in investigations of seed dormancy was noted.
Mapping the nesting habitats of saltwater crocodiles (Crocodylus porosus) in Melacca Swamp and the Adelaide River wetlands, Northern Territory: an approach using remote sensing and GIS
Authors: Harvey Kylie R. , Hill Greg J. E.
Published: September 2003

The utility of integrating remotely sensed data and other spatial information in a geographical information system (GIS) to model habitat suitability for nesting by saltwater crocodiles (Crocodylus porosus) was investigated in this study. The study areas, Melacca Swamp and the Adelaide River wetlands, are located 50 km east of Darwin, Northern Territory, and encompass areas of suitable nesting habitat for C. porosus. Melacca Swamp is a highly productive nesting area and is managed as a conservation reserve to protect its nesting habitat. Landsat TM, SPOT satellite imagery and large-scale colour aerial photography were evaluated for their utility in mapping habitats preferred for nesting by C. porosus within Melacca Swamp. Satellite imagery was capable of identifying generalised habitat classes used for nesting (e.g. open swamp with emergent trees). However, it was only with aerial photography that habitats could be discerned (e.g. sedges with scattered Melaleuca trees). Spatial information derived from satellite imagery and other sources was integrated in a GIS to model potentially suitable nesting habitat along the Adelaide River. This methodology effectively identified known preferred nesting areas of C. porosus on the basis of the analysis of environmental parameters (i.e. distance to water, vegetation type) that have an influence on selection of nesting habitat. The findings of this research demonstrate the utility of remote sensing and GIS for mapping nesting habitat of C. porosus at a range of scales and provide guidelines for application of the approaches used at the regional or State level.
Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. II. Distribution and diet
Authors: Sullivan B. J. , Norris W. M. , Baxter G. S.
Published: September 2003

This study used faecal pellets to investigate the broadscale distribution and diet of koalas in the mulgalands biogeographic region of south-west Queensland. Koala distribution was determined by conducting faecal pellet searches within a 30-cm radius of the base of eucalypts on 149 belt transects, located using a multi-scaled stratified sampling design. Cuticular analysis of pellets collected from 22 of these sites was conducted to identify the dietary composition of koalas within the region. Our data suggest that koala distribution is concentrated in the northern and more easterly regions of the study area, and appears to be strongly linked with annual rainfall. Over 50% of our koala records were obtained from non-riverine communities, indicating that koalas in the study area are not primarily restricted to riverine communities, as has frequently been suggested. Cuticular analysis indicates that more than 90% of koala diet within the region consists of five eucalypt species. Our data highlights the importance of residual Tertiary landforms to koala conservation in the region.
Koala mortality on roads in south-east Queensland: the koala speed-zone trial
Authors: Dique David S. , Thompson Jim , Preece Harriet J. , Penfold Guy C. , Villiers Deidré L. de , Leslie Ros S.
Published: September 2003

In 1995, the Queensland Parks and Wildlife Service, the Queensland Department of Main Roads and Redland Shire Council initiated the Koala Speed Zone Trial in the Koala Coast, south-east Queensland. The aim of the trial was to assess the effect of differential speed signs on the number of koalas (Phascolarctos cinereus) hit by vehicles in the Koala Coast from 1995 to 1999. On the basis of information collected by the Queensland Parks and Wildlife Service 1407 koalas were hit by vehicles in the Koala Coast during the five-year study (mean 281 koalas per year, range 251–315). Monitoring of vehicle speeds by the Queensland Department of Main Roads suggested that there was no significant reduction in vehicle speed during the trial period from August to December. Consequently, there was no evidence to suggest that a reduction in the number of koalas hit by vehicles occurred during the trial. Approximately 70% of koalas were hit on arterial and sub-arterial roads and approximately 83% did not survive. The location of each koala hit was recorded and the signed speed limit of the road was noted. Most koalas that were hit by vehicles were young healthy males. Pooling of data on koala collisions and road speed limits suggested that the proportion of koalas that survived being hit by vehicles was slightly higher on roads with lower speed limits. However, vehicle speed was not the only factor that affected the number of koalas hit by vehicles. It is suggested that habitat destruction, koala density and traffic volume also contribute to road-associated koala mortality in the Koala Coast.
Nestling growth and development in the brown falcon, Falco berigora: an improved ageing formula and field-based method of sex determination
Authors: McDonald Paul G.
Published: September 2003

The accurate determination of nestling age and sex is an important tool for studies that examine life-history traits and ecological interactions. Despite the widespread distribution of the brown falcon, Falco berigora, in Australia, morphological criteria for sexing nestlings of this species have yet to be published and nestling development has not been intensively studied. While an ageing formula for the species exists, the small sample from which it was derived precluded appropriate statistical assessment of independence problems and other potentially confounding variables such as hatch order and sex. This study used a larger sample of free-living nestlings to account for these factors and found the most reliable measure for ageing nestlings to be wing length. Wing length increased linearly with chick age, independent of seven other potentially confounding factors examined. Ageing formulae based on wing length before and after remiges emerge are presented. In addition, an accurate test for determining nestling sex at banding age, based on tarsus width, is proposed. Nestling chronology of this species is also described in detail for the first time. Nestling development was similar to that described for other Falconiformes; however, the chronology of nestling development was too variable to be useful in assigning chick age. Despite this, within 6 days of the eldest chick hatching the relative brightness of down and the degree to which chicks' eyes had opened were useful in assigning hatch order amongst nestlings with similar wing lengths.
Short-term logging and burning impacts on species richness, abundance and community structure of birds in open eucalypt forest in Western Australia
Authors: Abbott Ian , Mellican Amanda , Craig Michael D. , Williams Matthew , Liddelow Graeme , Wheeler Ian
Published: September 2003

In 1985 new silvicultural prescriptions for managing jarrah (Eucalyptus marginata) forest in south-west Western Australia came into operation. The most extreme logging treatment (gap release) involved removal of most of the overstorey from patches no larger than 10 ha, followed by a regeneration fire. In the other logging treatment (shelterwood), less wood was removed from a larger area, also followed by a fire. This study examined the impact of these disturbances on the avifauna by monitoring species richness and abundance of birds one year before logging, one year before burning, and for five years after burning. Although 68 bird species were recorded during the seven years of the study, 29 of these were detected fewer than 15 times. Of the other 39 bird species recorded, only two (Gerygone fusca and Acanthiza apicalis) showed a statistically significant treatment effect over time on their abundance. The abundance of G. fusca initially declined in the disturbed treatments and by Year 7 of the study (5 years post-fire) in the gap-release treatment had not recovered its original abundance. A. apicalis increased its abundance in both shelterwood and gap-release treatments. By Year 7, both species in the logged treatments had abundances similar to those in the unlogged treatments. Total abundance of all species varied little across treatments. Species richness was highest by Year 7 in the shelterwood and lowest in the gap-release treatment. In some years community structure varied more at the external-reference sites (not recently logged or burnt) than at the gap-release sites. In particular, there was little overlap in community structure in the external-reference treatment between the first and final years, whereas the pre-logging and final year in the gap-release treatment showed a high degree of overlap. These differences are suggestive of overriding short-term annual variation in broad-scale factors rather than local factors. Yearly variation in rainfall and temperature was documented; during low rainfall periods, populations of foliage arthropods may have been reduced.
Distribution and abundance of dugongs in Moreton Bay, Queensland, Australia
Authors: Lanyon Janet M.
Published: September 2003

Dugong abundances in Moreton Bay (south-east Queensland) were estimated during six bi-monthly aerial surveys throughout 1995. Sampling intensity ranged between 20 and 80% for different sampling zones within the Bay, with a mean intensity of 40.5%. Population estimates for dugongs were corrected for perception bias (the proportion of animals visible in the transect that were missed by observers), and standardised for availability bias (the proportion of animals that were invisible due to water turbidity) with survey and species-specific correction factors. Population estimates for dugongs in Moreton Bay ranged from 503 ± 64 (s.e.) in July to 1019 ± 166 in January. The highest uncorrected count was 857 dugongs in December. This is greater than previous population estimates, suggesting that either previous surveys have underestimated abundance and/or that this population may have increased through recruitment, immigration, or a combination of both. The high degree of variation in population estimates between surveys may be due to temporal differences in distribution and herding behaviour. In winter, dugongs were found in smaller herds and were dispersed over a wider area than in summer. The Eastern Banks region of the bay supported 80–98% of the dugong population at any one time. Within this region, there were several dugong 'hot spots' that were visited repeatedly by large herds. These 'hot spots' contained seagrass communities that were dominated by species that dugongs prefer to eat. The waters of Rous Channel, South Passage and nearby oceanic waters are also frequently inhabited by dugongs in the winter months. Dugongs in other parts of Moreton Bay were at much lower densities than on the Eastern Banks.
The conditional inactivation of the β-catenin gene in endothelial cells causes a defective vascular pattern and increased vascular fragility
Authors: Cattelino Anna , Liebner Stefan , Gallini Radiosa , Zanetti Adriana , Balconi Giovanna , Corsi Alessandro , Bianco Paolo , Wolburg Hartwig , Moore Robert , Oreda Boussadia , Kemler Rolf , Dejana Elisabetta
Published: September 2003

Using the Cre/loxP system we conditionally inactivated β-catenin in endothelial cells. We found that early phases of vasculogenesis and angiogenesis were not affected in mutant embryos; however, vascular patterning in the head, vitelline, umbilical vessels, and the placenta was altered. In addition, in many regions, the vascular lumen was irregular with the formation of lacunae at bifurcations, vessels were frequently hemorrhagic, and fluid extravasation in the pericardial cavity was observed. Cultured β-catenin −/− endothelial cells showed a different organization of intercellular junctions with a decrease in α-catenin in favor of desmoplakin and marked changes in actin cytoskeleton. These changes paralleled a decrease in cell–cell adhesion strength and an increase in paracellular permeability. We conclude that in vivo, the absence of β-catenin significantly reduces the capacity of endothelial cells to maintain intercellular contacts. This may become more marked when the vessels are exposed to high or turbulent flow, such as at bifurcations or in the beating heart, leading to fluid leakage or hemorrhages.
Site-specific inductive and inhibitory activities of MMP-2 and MMP-3 orchestrate mammary gland branching morphogenesis
Authors: Wiseman Bryony S. , Sternlicht Mark D. , Lund Leif R. , Alexander Caroline M. , Mott Joni , Bissell Mina J. , Soloway Paul , Itohara Shigeyoshi , Werb Zena
Published: September 2003

During puberty, mouse mammary epithelial ducts invade the stromal mammary fat pad in a wave of branching morphogenesis to form a complex ductal tree. Using pharmacologic and genetic approaches, we find that mammary gland branching morphogenesis requires transient matrix metalloproteinase (MMP) activity for invasion and branch point selection. MMP-2, but not MMP-9, facilitates terminal end bud invasion by inhibiting epithelial cell apoptosis at the start of puberty. Unexpectedly, MMP-2 also represses precocious lateral branching during mid-puberty. In contrast, MMP-3 induces secondary and tertiary lateral branching of ducts during mid-puberty and early pregnancy. Nevertheless, the mammary gland is able to develop lactational competence in MMP mutant mice. Thus, specific MMPs refine the mammary branching pattern by distinct mechanisms during mammary gland branching morphogenesis.
Microtubules provide directional cues for polarized axonal transport through interaction with kinesin motor head
Authors: Nakata Takao , Hirokawa Nobutaka
Published: September 2003

Post-Golgi carriers of various newly synthesized axonal membrane proteins, which possess kinesin (KIF5)-driven highly processive motility, were transported from the TGN directly to axons. We found that KIF5 has a preference to the microtubules in the initial segment of axon. Low dose paclitaxel treatment caused missorting of KIF5, as well as axonal membrane proteins to the tips of dendrites. Microtubules in the initial segment of axons showed a remarkably high affinity to EB1–YFP, which was known to bind the tips of growing microtubules. These findings revealed unique features of the microtubule cytoskeletons in the initial segment, and suggested that they provide directional information for polarized axonal transport.