bluuebunny/crossref_metadata_2025 huggingface dataset:
Web-Construction Behavior in Australian Phonognatha and the Phylogeny of Nephiline and Tetragnathid Spiders (Araneae, Tetragnathidae)
Authors: Hormiga G , Eberhard WG , Coddington JA
Published: June 2005

Details of web-construction behaviour and morphology support the monophyly of nephiline spiders with Phonognatha as the sister-group to the remaining nephiline genera examined in this study. Phylogenetic analysis of the behavioural data suggests that specialisations in nephiline building behaviour and web architecture did not evolve concurrently, and that some preceded the female giantism (not male dwarfism) for which nephiline spiders are well-known. Cladistic analysis of 60 characters supports the monophyly of both Tetragnathidae and Tetragnathinae. New data from spinneret silk gland spigots, combined with other morphological and behavioural characters, provide the first concrete evidence that 'metine' genera, occasionally regarded as either a distinct family or subfamily, are a paraphyletic assemblage.
Cocoon Formation and Structure in the Estivating Australian Desert Frogs, Neobatrachus and Cyclorana
Authors: Withers PC
Published: June 2005

Formation of a cocoon during aestivation is described for the Australian hylid frogs Cyclorana maini, C. novaehollandiae and C. platycephala, and the myobatrachid frogs Neobatrachus aquilonius, N. centralis, N. fulvus, N. kunapalari, N. pelobatoides, N. sudelli, N. sutor and N. wilsmorei. At the onset of aestivation, these frogs assume a 'water-conserving' posture and become inactive. A thin, transparent cocoon is observed to form within a week of onset of inactivity, and becomes progressively thicker and more opaque. The cocoon covers the entire body surface, including mouth, eyes and cloaca, except for the narial openings. The cocoon consists of an accumulation of multiple layers of single-cell-thick sheets of outer epidermal cells, formed at regular periods of about every two days (Cyclorana) to four days (Neobatrachus), that correspond to the normal shedding frequency. Each layer of the cocoon has a thickness of about 0.4 mu m (Cyclorana) to 0.6 mu m (Neobatrachus). The thickness of the cocoon and the number of layers increase progressively with duration of aestivation.
Sire Transmission of Acquired-Resistance to Myxomatosis
Authors: Parer I , Sobey WR , Conolly D , Morton R
Published: June 2005

Male rabbits that had recovered from myxomatosis transmitted to their offspring some factor that increased by 22% the offspring's probability of survival to myxoma virus challenge. The degree of protection transmitted differed between sires challenged with different myxoma strains and between sires challenged with myxoma virus and those challenged with Shope's fibroma virus (SFV). We suggest that future tests of the resistance of wild rabbits should be designed to minimise or eliminate the sire effect.
The Optic Chiasm of Australian Marsupials
Authors: Harman AM
Published: June 2005

The optic chiasm of mammals is the region of the nervous system in which optic axons have a choice of route, either they enter the optic tract on the same side of the brain or they cross the chiasm and enter the opposite optic tract. in eutherian (placental) mammals, axons approach the midline of the chiasm and then either continue across the chiasm or turn back to enter the tract on the same side of the brain. The midline of the chiasm provides guidance cues that repel uncrossed but not crossed axons. However, it has recently been shown that in a marsupial, the quokka wallaby, axons destined to stay on the same side of the brain remain in the lateral part of the optic nerve and chiasm and never approach the midline. The structure of the chiasm reflects this partitioning of axons with different routes by having a tripartite structure. The two lateral regions contain only uncrossed axons in rostral chiasmatic regions and the central region contains only crossed axons. Therefore, axons passing through the chiasm of this species must use guidance cues that differ from those of eutherian mammals. Here I show that the chiasms of species of both diprotodont and polyprotodont Australian marsupials have a similar tripartite structure and that uncrossed axons are confined to lateral regions. It seems likely, therefore, that the chiasm of marsupials has fundamental differences in structure and optic axon trajectory compared with that of eutherian mammals studied to date.
Reproductive-Biology of Megascolides Australis Mccoy (Oligochaeta, Megascolecidae)
Authors: Vanpraagh BD
Published: June 2005

Observations of gametogenesis facilitated understanding life history and reproductive processes in Megascolides australis, whose reproductive strategies are correlated with longevity, low density and poor dispersal ability. Worms are biparental and have a discrete breeding (egg laying) season in spring and summer. This coincides with the greatest number of mature ova and the glandular epidermis of the clitellar region being thickest. Gametogenesis occurs throughout the year, with sperm present in the spermathecae and available on male funnels ail year. Non-seasonal copulation may occur when two worms meet and conditions are favourable; this trait is advantageous for species in low densities with poor dispersal abilities. The spermathecal structure of M. australis differs from that of other megascolecids recorded in that the structure of the diverticulum includes many multiloculate chambers that do not connect directly with the spermathecal duct. The sperm form orientated bundles (spermatozeugmata) not previously described for Megascolecidae and are stored in the ampulla rather than the diverticula.
The Effects of Habitat on the Distribution of Culicoides Brevitarsis Kieffer (Diptera, Ceratopogonidae) During Its Resting Phase
Authors: Bishop AL , Mckenzie HJ , Barchia IM , Harris AM
Published: June 2005

Culicoides brevitarsis is a biting midge and a vector of several arboviruses affecting livestock in Australia. The effect of habitat on adults during their resting phase in pasture was studied in the Hunter Valley during 1994 and 1995. C. brevitarsis was 21 times more abundant in grass tussocks (Pea sp.) than in pasture grass and its numbers were related positively to the increasing size of these tussocks. High numbers were also found in reed tussocks (Juncus sp.) and grass along the margins of dams. When tussocks were absent in pasture, numbers of C. brevitarsis varied within the pasture grass during the day. More C. brevitarsis were found in grass when no cattle were present. The presence of cattle affected the parous ratio, with 85% of females being parous when cattle were absent and only 38% being parous when cattle were present. Counts in tussocks and grass were lowest and counts in the the air above tussocks were highest 1 h before sunset. After sunset, numbers increased on pasture grass more than in reed tussocks. Numbers in reed tussocks were again high after the morning flight peak the next day. Relationships with weather variables were weak.
Geographical and Temporal Distribution of the Common Armyworm, Mythimna Convecta (Lepidoptera: Noctuidae), in Eastern Australia: Larval Habitats and Outbreaks
Authors: Mcdonald G , New TR , Farrow RA
Published: June 2005

Surveys for juvenile Mythimna convecta throughout the agricultural and arid regions of eastern Australia were conducted from 1986 to 1989. Armyworm populations north of 33 degrees S were generally dominated by M. convecta, and further south by Persectania ewingii. M. convecta was most widely distributed in spring. Incidence during autumn and winter ranged from very low in Victoria to high in northern New South Wales and southern Queensland. Summer infestations were found mostly on the south-east coast where favourable habitats were abundant. Colonised habitats included extremely arid regions, where small numbers of larvae were associated with grasses in temporary watercourses, and the higher-rainfall, eastern regions. The largest infestations occurred in south-east Queensland and north central and north-east New South Wales, particularly after heavy autumn rains. There appeared to be two generations of M. convecta over the autumn/winter period: the first a synchronised event starting on the autumn rains and the second commencing in June/July and comprising a wide spread in age distribution. The progeny of the winter generation are probably the source of most economic outbreaks. Mythimna convecta larvae were collected from subtropical and temperate grasses. In the former, most larvae were found in tussocks, particularly of Dichanthium sericeum and Chloris truncata, which provided a dense, fine-leaf crown and canopy. After good autumn rainfall and vegetative growth, the wiry-stemmed tussocks, including Astrebla spp. and C. ciliaris, were also common hosts. The temperate grasses, particularly Avena fatua and Hordeum leporinum, were the main winter hosts although the greatest densities were found only in thick swards of growth, particularly those that contained dried grass. Two of the largest surveys, in autumn 1987 and 1988, followed periods of heavy rain and provided strongly contrasting results. The 1987 survey of central and south-west Queensland located no M. convecta larvae, indicating that densities were below detection thresholds. The paucity of larvae was attributed to lack of suitable atmospheric conditions to assist moth immigrations and absence of adequate populations in potential source areas. The 1988 survey revealed a major outbreak of M. convecta larvae in south-east Queensland and northern New South Wales. The area received record rains during early April of that year, and the outbreak probably arose from moth migrations from the east and south-east coast. An outbreak of similar scale occurred after further heavy autumn rains in 1989.
Group Structure and Behaviour of Babirusa (Babyrousa Babyrussa) in Northern Sulawesi
Authors: Patry M , Leus K , Macdonald AA
Published: June 2005

Studies were carried out at two 'salt-licks' in lowland tropical forest on North Sulawesi, Indonesia. During 60 days of observation 586 sightings of babirusa were made, comprising 161 adult males, 155 adult females, 11 adults of unknown sex, 78 subadult males, 53 subadult females and 34 subadults of indeterminate sex; juveniles were observed 94 times, 19 males, 12 females and 63 of unknown sex. We saw 226 groups ranging in size from one to eight animals (median = 2). Almost half the sightings were of solitary animals, usually adult males. Bachelor groups of four or more babirusa were never seen. Adult females were rarely seen without company, often both juveniles and subadults being sighted together with them. There were never more than three adult females in a group. There were about twice as many family groups without adult males as there were with males. Agonistic behaviour between males was confined to 'threat at a distance', 'nose in the air', 'head under jaw submission' and 'front half supported' behaviours. Incidents of female-female agonistic behaviour were fewer, but in two, the dominant female chased her inferior off the 'salt-lick'.
Wing Morphology and Flight Behaviour of the Golden-Tipped Bat, Phoniscus Papuensis (Dobson) (Chiroptera: Vespertilionidae)
Authors: Rhodes MP
Published: June 2005

The wing morphology and flight performance of Phoniscus papuensis was examined to determine whether the wing morphology reflected published observations of flight behaviour and habitat preference. Wingspan and wing area were above the vespertilionid average for its mass. The wing loading and aspect ratio were below average. The wing loading is the lowest of any Australian vespertilionid. P. papuensis was able to successfully negotiate arrays of obstacles 22 cm apart 60% of the time. This ability, and the extremely broad, lightly loaded wings, afford the species unique flight characteristics which have been observed in the field and allow flight in complex, 'closed' habitats.
Significance of Back Colour in Territorial Interactions in the Australian Magpie
Authors: Kallioinen RUO , Hughes JM , Mather PB
Published: June 2005

In eastern Australia, two forms of the Australian magpie occur: a white-backed form and a black-backed form. These two forms hybridise across northern Victoria and into South Australia. In this study the response of territorial magpies to caged intruders was examined. Pairs of adult male magpies were introduced into territories. Both were adult black-backed birds, but in each case one of them had its back painted white. The pair was introduced to each territory twice, with the bird that was painted white differing between times. The experiment was run in a population of black-backed birds and a population in the hybrid zone containing white-backed, black-backed and hybrid birds. In both cases, the residents were more aggressive towards the intruder with the white-back than they were to the black-backed intruder. We suggest that this may be because a white-backed bird posed more of a threat to residents than a black-backed bird.
Molecular Relationships Within Australasian Waterfowl (Anseriformes)
Authors: Sraml M , Christidis L , Easteal S , Horn P , Collet C
Published: June 2005

Within Australia there are 19 endemic species of Anseriformes. Six of these belong to monotypic genera, some of which remain controversial with respect to phylogenetic relationships. Sequence variation in a 307-base pair fragment of the cytochrome-b gene was compared from 23 species of waterfowl (the Cairina sequence was obtained from the literature) to elucidate further the relationships of these monotypic Australian genera. Anseranas and Dendrocygna were identified as the earliest diverged genera among the taxa examined. The remaining genera fell into two groups: (1) Tadorna, Alopochen, Chenonetta, Anas, Aythya, Cairina and Air and (2) Cygnus, Branta, Cereopsis, Biziura, Oxyura, Malacorhynchus, Stictonetta and Nettapus. The controversial nature of the last group is discussed.
Solar Absorptance of Some Australian Lizards and Its Relationship to Temperature
Authors: Christian KA , Bedford GS , Shannahan ST
Published: June 2005

The absorptance to solar radiation, integrated across a wide range of wavelengths, was measured for selected species of Australian lizards. Some, but not all, agamids demonstrated the ability to change absorptance. None of the varanid lizards measured changed absorptance, including Varanus storri, which had been reported to change colour. An energy balance model was used to explore the effects of absorptance, changes in absorptance, and body size in varanid lizards, the dragon Ctenophorus caudicinctus (which changed absorptance from 77.0 to 87.7%) and the frillneck lizard (Chlamydosaurus kingii). Although higher absorptance values generally result in higher body temperatures, the effect of body size is great and must be taken into account in comparisons. Although some species with high absorptances are associated with relatively cool climates (Varanus rosenbergi) or with a semi-aquatic lifestyle (V. mertensi), the absorptances of other species are not as easily explained [such as the high absorptances of the tropical terrestrial V. panoptes (87%) and the tropical arboreal V. scalaris (86%)]. The absorptances of more species are required before the importance of climate and phylogenetic relationships can be fully evaluated. To facilitate future measurements, the apparatus used in this study is described in detail.
Proportional Weekly Use of Underwater Call Types by Weddell Seals, Leptonychotes Weddellii (Pinnipedia: Phocidae), During the Breeding Season at the Vestfold Hills
Authors: Pahl BC , Terhune JM , Burton HR
Published: June 2005

Underwater vocalisations by Weddell seals, Leptonychotes weddellii, were recorded during the 1992 breeding season, at the Vestfold Hills, Antarctica. Only 3 of the 12 major call types recorded at all sites had statistically significant variations in utilisation throughout the season. No consistent trends were evident. The underwater calls of Weddell seals increased;in number during the breeding season, hut the proportional weekly usage of each of the major call types did not change. The absence of vocalisation changes suggests that the breeding behaviours of Weddell seals are not synchronous and that the underwater behavioural patterns either do not change during the breeding season or could not be detected because of the asynchrony.
Water and Energy Balance of Captive and Free-Ranging Spinifexbirds (Eremiornis Carteri) North (Aves:Sylviidae) on Barrow Island, Western Australia
Authors: Ambrose SJ , Bradshaw SD , Withers PC , Murphy DP
Published: June 2005

The mean annual rainfall of Barrow Island, located about 90 km north of Onslow off the arid Western Australian coast, is 324 mm, 74% of which falls as cyclonic rain between February and May. Spinifexbirds captured in May 1992 had a mean body mass of 12.3 +/- 0.3 g and a total body water content (TBW) of 774 +/- 1.6%. In December 1992 the mean body mass was significantly lower (11.7 +/- 0.2 g; P < 0.05), despite a TBW of 73.4 +/- 1.0%. Spinifexbirds maintained water balance in both seasons, but water flux rates were significantly higher in May (P = 0.01). Respective influx and efflux rates in May were 0.70 +/- 0.30 and 0.72 +/- 0.03 mL (g day)(-1) compared with 0.60 +/- 0.04 and 0.57 +/- 0.04 mL (g day)(-1) in December. Field metabolic rates (FMRs), measured with doubly-labelled water ((3)HH(18)0), did not differ significantly between the two periods. The mean FMR in May was 6.8 +/- 0.6 mL CO2 (g h)(-1) compared with 7.2 +/- 0.9 mL CO2 (g h)(-1) in December, similar to rates predicted by Nagy and Peterson (1988) for a similar-sized passerine. The thermoneutral zone (TNZ) of spinifexbirds, determined by metabolic laboratory trials in December, extended from 30 to 39 degrees C. The standard metabolic rate (SMR) within the TNZ was 2.9 +/- 0.1 mL O-2 (g h)(-1), which is up to 20% lower than predicted values. Body temperature was maintained at 39.1 degrees C in the TNZ, but birds became hyperthermic at ambient temperatures (T(a)s) higher than 35 degrees C, with body temperatures reaching 44 degrees C. Wet thermal conductance and evaporative water loss increased markedly at T(a)s > 35 degrees C. The data suggest that spinifexbirds have limited physiological adaptations to desert conditions compared with some other arid-zone birds.
Foraging Behaviour of Trigona Carbonaria (Hymenoptera: Apidae) at Multiple-Choice Feeding Stations
Authors: Bartareau T
Published: June 2005

To examine the foraging behaviour of the stingless bee Trigona carbonaria Sm., a full-size colony was placed at the centre of a grid of multiple-choice feeding stations with feeders containing water and three sugar solutions at 10, 20 and 40% concentration. The feeding of workers at feeders was monitored during consecutive days under these variable resource conditions. Scouts marked all the sugar-solution feeders with a visible fluid, and the degree of marking and nestmate recruitment was positively correlated with sugar concentration. Workers exhibited characteristics of the group-foraging behaviour termed 'opportunism', whereby many foragers search independently in the field, until one of them finds an exceptional sugar-solution resource and then rapidly recruits nestmates. Overall, workers preferred the 40% sugar feeders, visitation rates decreased with increasing distance from the nest, and visits at the 20 and 10% feeders increased in that sequence when replenishment with sugar solution was interrupted and sugar concentrations declined progressively in the 40 and 20% feeders. These results show that workers have the physiological ability to identify the richest sugar solutions, but indicate that food choice will vary with resource variability. The evidence suggests that the primary strategy involved in the foraging behaviour of this species is to optimise the feeding intake of the colony.
Ecology of the Pygmy Goanna (Varanus Brevicauda) in Spinifex Grasslands of Central Australia
Authors: James CD
Published: June 2005

The reproductive biology, growth, movements, density and habitat use of Varanus brevicauda are presented. V. brevicauda is the smallest extant species of goanna. It is an inhabitant of the spinifex grasslands of central and western deserts and is rarely seen, so little is known of its ecology. Reproductive biology was determined from dissection of preserved museum specimens. Other ecological data were collected over three years from 111 V. brevicauda captured in pit-traps on a spinifex-dominated sand-dune environment in central Australia. V. brevicauda breed in spring when males have enlarged testes (July-November) and females are developing eggs (October-December). Clutch sizes of 2-3 eggs were found, but clutch sizes of 4-5 eggs have been reported. Eggs hatch from late January to February and neonates have a SVL of 42 mm. Sexual maturity, determined from preserved museum specimens, occurs at about 70 mm SVL for males, and 83 mm SVL for females, but small sample sizes for females make this estimate unreliable. The von Bertalanffy equation modelled growth in V. brevicauda better than logistic-by-length or logistic-by-weight equations. Parameter estimates for the von Bertalanffy equation are asymptotic body size (a) = 101.6 +/- 1.4 and characteristic growth rate (k) = 0.0029 +/- 0.0003. Males may grow to sexual maturity by their first spring at an age of 10 months, and females are unlikely to be sexually mature until their second spring at 22 months of age. V. brevicauda appear to be relatively sedentary with average displacements of 14-25 m over time intervals of up to 751 days. V. brevicauda were most abundant on the crests of sand dunes where densities were about 20 adults per ha. This abundance is surprising given the rarity of casual sightings. V. brevicauda is unusual compared with other sympatric species of Varanus because it is secretive, relatively sedentary and apparently abundant.
Molecular Perspectives on the Phylogenetic Affinities of Lyrebirds (Menuridae) and Treecreepers (Climacteridae)
Authors: Christidis L , Norman JA , Scott IAW , Westerman M
Published: June 2005

Within the Australo-Papuan region, DNA-DNA hybridisation studies revealed a major radiation among the oscine songbirds. Although many of the relationships revealed have been corroborated by other molecular evidence, the apparent relationship between lyrebirds, treecreepers and bowerbirds remains controversial. To examine this issue, a 924-bp fragment of the cytochrome-b gene was sequenced from a lyrebird and treecreeper and compared with published sequences of other Australo-Papuan songbirds. Despite possessing several distinctive morphological features, lyrebirds and treecreepers are part of the oscine assemblage. Although less conclusive, the cytochrome-b data also provide some support for a grouping of lyrebirds with treecreepers. These may also be linked with honeyeaters or bowerbirds. On the basis of current molecular evidence, the Australo-Papuan songbird radiation is clearly the most divergent oscine assemblage in terms of morphological adaptations.
The Median Tentacle of the Larva of Lingula Anatina (Brachiopoda) From Queensland, Australia
Authors: Lüter C
Published: June 2005

The median tentacle of the larvae of Lingula anatina has been investigated in order to obtain information about the morphological implications of its function and its relation to the paired tentacles of the larval lophophore. The median tentacle is a larval sensory organ with apical, intraepidermal collar receptors and a basiepidermal nervous system (apical ganglion). The monociliated muscle cells in the median tentacle form a compact musculature; where cilia emanate from the single cells, small compartments surrounded by three epithelial muscle cells can be observed. The number of cavities corresponds with the number of muscle cells. In the proximal part of the median tentacle these muscle cells build a continuous transition to the muscle cells in the paired tentacles; an extracellular matrix could not be found in the contact-region between both muscular systems. Because of this continuity the muscle cells in the median tentacle must be regarded as part of the mesosome. The unpaired median tentacle is restricted to the larvae of all species of the Lingulida and Discinida within the inarticulate brachiopods and is lacking in all other brachiopod larvae. Because it is also unknown in Phoronida, it could be regarded as a synapomorphic characteristic of the supraspecific taxa Lingulida and Discinida.
A Systematic Revision of Melomys (Rodentia:Muridae) of New Guinea
Authors: Menzies JI
Published: June 2005

A program of multi-variate discriminant analysis is used to separate approximately 900 specimens, currently identified as species of the genus Melomys, into significantly different taxa at generic, specific and subspecific level. A combination of metric characters and multistate characters is used to indicate phenetic relationships between the taxa previously identified. Metric characters are used in combination with multistate characters to provide diagnoses of genera, and species and subspecies within genera. As a result, Melomys is redefined to include only four species, rufescens, leucogaster, lutillus and frigicola, in New Guinea. Nine species are included in Paramelomys, raised from its previous subgeneric rank. Two species formerly included in Melomys (lanosus and rattoides) are removed to a new genus. Melomys fellowsi is removed to another new genus. Some comments on the generic disposition of extralimital species are made.
Use of Den Trees by Leadbeater's Possum (Gymnobelideus Leadbeateri)
Authors: Lindenmayer DB , Meggs RA
Published: June 2005

The results of a radio-tracking study of the uses of den trees by Leadbeater's possum (Gymnobelideus leadbeateri McCoy) at Cambarville in the mountain ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, south-eastern Australia, are described. Animals were radio-tracked for three periods of 5-20 days in July 1990, November 1990 and July 1991. A total of 14 individuals was tracked and they occupied 11 different trees with hollows on the 10-ha study site. Preliminary findings showed that some animals moved between hollows in different trees, and most animals used two or more trees. The distances between utilised trees usually exceeded 50 m. Possible reasons for the den-swapping behaviour include attempts to either or both relieve burdens of ecto-parasites and to reduce the risk of predation. There were several examples, in each of the three radio-tracking periods, of two or more radio-collared adult breeding female animals simultaneously co-occupying the same nest tree. This result was different from some of the general findings of an earlier study of G. leadbeateri at Cambarville.
Variation in commercial rodent diets induces disparate molecular and physiological changes in the mouse uterus
Authors: Wang Haibin , Tranguch Susanne , Xie Huirong , Hanley Gregory , Das Sanjoy K. , Dey Sudhansu K.
Published: June 2005

Although ovarian estrogen, estradiol-17β, is a key modulator of normal reproductive functions, natural and synthetic compounds with estrogen-like activities can further influence reproductive functions. Plant-derived phytoestrogens specifically have received much attention because of associated health benefits. However, a comprehensive understanding of the beneficial and/or detrimental impacts of phytoestrogen consumption through commercial rodent diets on uterine biology and early pregnancy at the molecular level remains largely unexplored. Using multiple approaches, we demonstrate here that exposure of adult female mice to a commercial rodent diet with higher phytoestrogen levels facilitates uterine growth in the presence or absence of ovarian estrogen, alters uterine expression of estrogen-responsive genes, and advances the timing of implantation compared with a diet with lower phytoestrogen levels. The finding that variability in phytoestrogen content in commercial rodent diets, both within and between brands, influences experimental results stresses the importance of this investigation and raises caution for investigators using rodents as animal models.
Evolution of 3-deoxy-
d
-
arabino
-heptulosonate-7-phosphate synthase-encoding genes in the yeast
Saccharomyces cerevisiae
Authors: Helmstaedt Kerstin , Strittmatter Axel , Lipscomb William N. , Braus Gerhard H.
Published: June 2005

The shikimate pathway resulting in three aromatic amino acids is initiated in different organisms by two and three 3-deoxy-
d
-
arabino
-heptulosonate-7-phosphate synthases, respectively. Aro3p and Aro4p are the yeast enzymes feedback-inhibited by phenylalanine and tyrosine, respectively. A yeast strain deficient in the general control transcriptional regulatory system of amino acid biosynthesis is unable to live in the presence of high amounts of phenylalanine and tyrosine. Here, we show that this yeast strain can be rescued by the expression of
aroH
from
Escherichia coli
encoding the tryptophan-regulated AroH as third isoenzyme. Yeast carrying Ec AroH as the only enzyme for the initial step of the shikimate pathway can grow in the absence of tryptophan. Without aromatic amino acids, this yeast strain survives only when the yeast
ARO3
promoter instead of the
ARO4
promoter drives
E. coli aroH
. The detailed analysis of Aro3p and Aro4p revealed a triple feedback control by tyrosine/phenylalanine and tryptophan. Dissecting this control allowed engineering of Aro4p S195A as an enzyme, which is inhibited like AroH only by tryptophan. In addition, Aro4p variants were constructed that show an equally strong inhibition by tyrosine and tryptophan (Aro4p P165G Q302R) and in which the regulation by tyrosine and tryptophan was reversed (Aro4p P165G). Our data suggest that yeast possesses only two instead of three isogenes encoding 3-deoxy-
d
-
arabino
-heptulosonate-7-phosphate synthases because both isoenzymes can be fine tuned by tryptophan as additional effector and because transcriptional regulation by the general control system can be induced as backup when aromatic amino acids in the environment are imbalanced.
Involvement of PI3K and MAPK Signaling in bcl-2-induced Vascular Endothelial Growth Factor Expression in Melanoma Cells
Authors: Trisciuoglio Daniela , Iervolino Angela , Zupi Gabriella , Del Bufalo Donatella
Published: June 2005

We have previously demonstrated that bcl-2 overexpression in tumor cells exposed to hypoxia increases the expression of vascular endothelial growth factor (VEGF) gene through the hypoxia-inducible factor-1 (HIF-1). In this article, we demonstrate that exposure of bcl-2 overexpressing melanoma cells to hypoxia induced phosphorylation of AKT and extracellular signal-regulated kinase (ERK)1/2 proteins. On the contrary, no modulation of these pathways by bcl-2 was observed under normoxic conditions. When HIF-1α expression was reduced by RNA interference, AKT and ERK1/2 phosphorylation were still induced by bcl-2. Pharmacological inhibition of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways reduced the induction of VEGF and HIF-1 in response to bcl-2 overexpression in hypoxia. No differences were observed between control and bcl-2-overexpressing cells in normoxia, in terms of VEGF protein secretion and in response to PI3K and MAPK inhibitors. We also demonstrated that RNA interference-mediated down-regulation of bcl-2 expression resulted in a decrease in the ERK1/2 phosphorylation and VEGF secretion only in bcl-2-overexpressing cell exposed to hypoxia but not in control cells. In conclusion, our results indicate, for the first time, that bcl-2 synergizes with hypoxia to promote expression of angiogenesis factors in melanoma cells through both PI3K- and MAPK-dependent pathways.
The E. coli NusA carboxy‐terminal domains are structurally similar and show specific RNAP‐ and λN interaction
Authors: Eisenmann Anke , Schwarz Sabine , Prasch Stefan , Schweimer Kristian , Rösch Paul
Published: June 2005

The carboxy‐terminal domain of the transcription factor Escherichia coli NusA, NusACTD, interacts with the protein N of bacteriophage λ, λN, and the carboxyl terminus of the E. coli RNA polymerase α subunit, αCTD. We solved the solution structure of the unbound NusACTD with high‐resolution nuclear magnetic resonance (NMR). Additionally, we investigated the binding sites of λN and αCTD on NusACTD using NMR titrations. The solution structure of NusACTD shows two structurally similar subdomains, NusA(353–416) and NusA(431–490), matching approximately two homologous acidic sequence repeats. Further characterization of NusACTD with 15N NMR relaxation data suggests that the interdomain region is only weakly structured and that the subdomains are not interacting. Both subdomains adopt an (HhH)2 fold. These folds are normally involved in DNA–protein and protein–protein interactions. NMR titration experiments show clear differences of the interactions of these two domains with αCTD and λN, in spite of their structural similarity.
Glucosylation of β‐lactoglobulin lowers the heat capacity change of unfolding; a unique way to affect protein thermodynamics
Authors: Van Teeffelen Annemarie M.M. , Broersen Kerensa , de Jongh Harmen H.J.
Published: June 2005

Chemical glycosylation of proteins occurs in vivo spontaneously, especially under stress conditions, and has been linked in a number of cases to diseases related to protein denaturation and aggregation. It is the aim of this work to study the origin of the change in thermodynamic properties due to glucosylation of the folded β‐lactoglobulin A. Under mild conditions Maillard products can be formed by reaction of ε‐amino groups of lysines with the reducing group of, in this case, glucose. The formed conjugates described here have an average degree of glycosylation of 82%. No impact of the glucosylation on the protein structure is detected, except that the Stokes radius was increased by ∼3%. Although at ambient temperatures the change in Gibbs energy of unfolding is reduced by 20%, the denaturation temperature is increased by 5°C. Using a combination of circular dichroism, fluorescence, and calorimetric approaches, it is shown that the change in heat capacity upon denaturation is reduced by 60% due to the glucosylation. Since in the denatured state the Stokes radius of the protein is not significantly smaller for the glucosylated protein, it is suggested that the nonpolar residues associate to the covalently linked sugar moiety in the unfolded state, thereby preventing their solvent exposure. In this way coupling of small reducing sugar moieties to solvent exposed groups of proteins offers an efficient and unique tool to deal with protein stability issues, relevant not only in nature but also for technological applications.
A scalable, GFP‐based pipeline for membrane protein overexpression screening and purification
Authors: Drew David , Slotboom Dirk‐Jan , Friso Giulia , Reda Torsten , Genevaux Pierre , Rapp Mikaela , Meindl‐Beinker Nadja M. , Lambert Wietske , Lerch Mirjam , Daley Daniel O. , Van Wijk Klaas‐Jan , Hirst Judy , Kunji Edmund , De Gier Jan‐Willem
Published: June 2005

We describe a generic, GFP‐based pipeline for membrane protein overexpression and purification in Escherichia coli. We exemplify the use of the pipeline by the identification and characterization of E. coli YedZ, a new, membrane‐integral flavocytochrome. The approach is scalable and suitable for high‐throughput applications. The GFP‐based pipeline will facilitate the characterization of the E. coli membrane proteome and serves as an important reference for the characterization of other membrane proteomes.
Crystal structure and substrate specificity of the β‐ketoacyl‐acyl carrier protein synthase III (FabH) from Staphylococcus aureus
Authors: Qiu Xiayang , Choudhry Anthony E. , Janson Cheryl A. , Grooms Michael , Daines Robert A. , Lonsdale John T. , Khandekar Sanjay S.
Published: June 2005

β‐Ketoacyl‐ACP synthase III (FabH), an essential enzyme for bacterial viability, catalyzes the initiation of fatty acid elongation by condensing malonyl‐ACP with acetyl‐CoA. We have determined the crystal structure of FabH from Staphylococcus aureus, a Gram‐positive human pathogen, to 2 Å resolution. Although the overall structure of S. aureus FabH is similar to that of Escherichia coli FabH, the primer binding pocket in S. aureus FabH is significantly larger than that present in E. coli FabH. The structural differences, which agree with kinetic parameters, provide explanation for the observed varying substrate specificity for E. coli and S. aureus FabH. The rank order of activity of S. aureus FabH with various acyl‐CoA primers was as follows: isobutyryl‐ > hexanoyl‐ > butyryl‐ > isovaleryl‐ >> acetyl‐CoA. The availability of crystal structure may aid in designing potent, selective inhibitors of S. aureus FabH.
Evolution of nocturnal flight calls in migrating wood‐warblers: apparent lack of morphological constraints
Authors: Farnsworth Andrew , Lovette Irby J.
Published: June 2005

Many migratory songbirds produce flight calls that vary, sometimes strikingly, among species in duration, frequency, modulation, and pattern, and little is known about what factors are responsible for this variation. Negative correlations between body mass or bill length and song frequencies are well documented in birds, but no studies have examined these associations for flight calls. We explored relationships between flight call and song frequencies and body mass or bill length in 33 species of wood‐warblers. Phylogenetically controlled and uncontrolled analyses showed no significant relationship between body mass or bill length and flight call frequency; however, we found significant differences between flight call and song frequencies and a significant relationship between maximum frequencies of flight calls and songs. Our findings suggest that factors other than body mass and bill length are responsible for variation in flight call frequencies in wood‐warblers. We suggest that different ecological and atmospheric properties might play important roles in selection for flight call frequencies.
Gingival fibromatosis and significant tooth eruption delay in an 11‐year‐old male: a 30‐month follow‐up
Authors: KAVVADIA K. , PEPELASSI E. , ALEXANDRIDIS C. , ARKADOPOULOU A. , POLYZOIS G. , TOSSIOS K.
Published: June 2005

This case report describes the dental management of an unusual case of idiopathic gingival fibromatosis with multiple impacted primary teeth, and the absence of eruption of permanent teeth, in an 11‐year‐old boy and at the 30‐month follow‐up. The patient presented with severely enlarged gingival tissues affecting both arches and multiple retained and nonerupted primary teeth. He had already been subjected to localized gingivectomies at the ages of 7 and 9 years. He had no known syndrome and there was no family history of any similar disorder. The patient was treated under general anaesthesia to remove the excessive gingival tissues using apically positioned flaps. During the surgical procedure, over‐retained and unerupted impacted primary teeth were extracted in order to facilitate the eruption of the permanent successors. Two years postoperatively, there was no recurrence of the gingival enlargement. Overdentures were then constructed because none of the permanent teeth had yet erupted. Furthermore, preeruptive coronal resorption was detected radiographically affecting the crown of the unerupted 36. Thirty months postoperatively, no recurrence of gingival enlargement was seen, but the permanent teeth had still not erupted.
Bond strengths of eight contemporary adhesives to enamel and to dentine: an in vitro study on bovine primary teeth
Authors: ATASH R. , VAN DEN ABBEELE A.
Published: June 2005

Objectives.  The aim of this study was to compare the shear and tensile bond strengths of eight adhesive systems to the enamel and dentine of primary bovine teeth.

Methods.  Two hundred and fifty‐six noncarious bovine mandibular primary incisors were collected and stored in an aqueous 1% chloramine solution at room temperature for no longer than 3 months after extraction. The tested adhesives were: Clearfil SE bond (SE); Adper Prompt L Pop (LP); Optibond Solo Plus Self‐etch (OB); AdheSE (AS); Xeno III (XE); Scotch Bond 1 (SB); Etch & Prime 3·0 (EP); and I Bond (IB). For the shear bonding test and the tensile bonding test, the labial surfaces of primary incisors were used. To obtain a flat surface, the labial surfaces of the teeth were sanded on wet silicon carbide paper, first with number 200 grit for 20 s and then with number 600 grit for 60 s (n = 128; 64 for shear bonding and 64 for tensile bonding). The results were compared with an analysis of variance and Bonferroni's multiple comparison test.

Results.  Shear bond strength values ranged from 18·1 to 8·9 MPa on enamel (in decreasing order, SE, LP, OB, AS, XE, SB, EP and IB), and from 17·8 to 8·2 MPa on dentine (in decreasing order, SE, SB, OB, AS, XE, LP, IB and EP). Tensile bond strength values ranged from 13·1 to 6·7 MPa on enamel (in decreasing order, SE, OB, AS, LP, XE, IB, SB and EP), and from 12·1 to 5·7 MPa on dentine (in deceasing order, SE, SB, OB, AS, XE, LP, IB and EP). The differences in bond strengths between the eight systems on enamel and dentine were all statistically significant. This was true for both the shear and tensile bond strengths.

Conclusions.  The highest shear bond strength was achieved by SE on enamel and dentine, and the lowest by IB on enamel and EP on dentine. The highest tensile bond strength was obtained by SE on enamel and dentine, and the lowest by EP. Shear bond strengths were significantly higher on enamel when compared to dentine for five of the eight adhesives systems, and tensile bond strengths were significantly higher on enamel when compared to dentine for all but two systems.
Oral health of southern Chinese children and adolescents with severe hypodontia
Authors: WONG A. T. Y. , MCGRATH C. , MCMILLAN A. S.
Published: June 2005

Objective.  The aim of this study was to assess the oral health condition of southern Chinese children and adolescents with severe hypodontia.

Methods.  This was a cross‐sectional clinical study in the dental teaching hospital in Hong Kong. Twenty‐five children and adolescents with severe hypodontia, and a comparison group of 25 age‐ and gender‐matched controls took part. Verified clinical examination techniques were used to assess the pattern of missing teeth, tooth spacing, dental caries, periodontal condition, enamel defects, and tooth wear. Statistical comparisons were made between groups using independent Student t‐tests and chi‐square tests.

Results.  The mean number of congenitally missing permanent teeth in the severe hypodontia group was 9·1 (SD = 5·0), with the maxillary lateral incisor being the most common missing tooth (14·5%). There were significant space discrepancies in both jaws between groups (P < 0·001). Caries prevalence was low with no difference between groups. There was no difference in periodontal condition between groups, with about half of the participants having no gingival inflammation. The severe hypodontia group had more enamel defects (P = 0·043), enamel hypoplasia (P = 0·044) and tooth wear (P = 0·005) than the comparison group. Three of the severe hypodontia group had ectodermal dysplasia.

Conclusions.  The oral health condition of southern Chinese children and adolescents with severe hypodontia was good in terms of caries experience and periodontal health. However, the increased prevalence of developmental defects of enamel and tooth wear complicates already complex interim and definitive prosthodontic management, and may increase psychosocial impact.
Sealant and composite bond strength to enamel with antibacterial/self‐etching adhesives
Authors: EMINKAHYAGIL N. , GOKALP S. , KORKMAZ Y. , BASEREN M. , KARABULUT E.
Published: June 2005

Introduction.  The enamel in pits and fissures undergoing preventive or ultraconservative resin restorations may be affected by secondary caries. An antibacterial adhesive bond may be a useful choice to prevent and reduce demineralization.

Objectives.  The purpose of this study was to determine the shear bond strength of an experimental antibacterial bond, a self‐etch bond, and an ormocer‐based adhesive bond using an ormocer‐based fissure sealant and a composite resin on intact enamel.

Methods.  Twenty‐four extracted human molars were sectioned bucco‐lingually to obtain two flat and sound enamel surfaces. Forty‐eight specimens were randomly assigned into four groups. The groups were prepared to receive the following treatments: (1) Admira Bond + Admira Seal (n = 10); (2) ABF Bond + Admira Seal (n = 11); (3) Clearfil SE Bond + Clearfil AP‐X (n = 12); and (4) ABF Bond + Clearfil AP‐X (n = 11). A cylindrical mould was placed over the bonded surface, and both materials were applied according to the instructions. The teeth were thermocycled 500 cycles between 5 and 55° with a dwell time of 30 s. For shear bond strength testing, the load was applied vertically to the base of the mould. The cross‐head speed was 5 mm min−1.

Results.  The maximum load that a specimen can withstand until failure was determined and shear bond strength was calculated by dividing the load at failure by the surface area of the mould. The results (median, minimum and maximum, respectively) for the four groups were: (1) 7·9, 4·2 and 13·6 MPa; (2) 8·6, 2·6 and 15·9 MPa; (3) 5·9, 5·3 and 8·2 MPa; and (4) 8·8, 3.0 and 19·2 MPa. Kruskal–Wallis and Mann–Whitney U‐tests were performed for the statistical analysis. Groups 3 and 4 were statistically significantly different (P = 0·005; P < 0·05). There was no statistically significant difference between the sealant and composite groups for ABF (P = 0·375). Fracture sites were viewed by microscope under × 16 magnification to determine if the mode of failure was adhesive or cohesive. The results (number of adhesive failed specimens and number of cohesive failed specimens, respectively) for the four groups were: (1) 7 and 3; (2) 3 and 8; (3) 2 and 9; and (4) 8 and 3.

Conclusion.  The ABF bond has sufficiently physical qualities to be used under fissure sealant and composite resin on uncut enamel, its antibacterial efficiency notwithstanding.