bluuebunny/crossref_metadata_2025 huggingface dataset:
The universally conserved HCF101 protein is involved in assembly of [4Fe‐4S]‐cluster‐containing complexes in Arabidopsis thaliana chloroplasts
Authors: Lezhneva Lina , Amann Katrin , Meurer Jörg
Published: October 2010

The seedling‐lethal nuclear Arabidopsis hcf101 (high chlorophyll fluorescence) mutant is impaired in photosynthesis and complemented by the wild‐type HCF101 cDNA. Photosystem I (PSI) activity is abolished, and PSI core complexes fail to accumulate in hcf101, whereas levels of other thylakoid membrane proteins are unaffected. Northern and in vivo labelling analyses as well as studies on polysome loading show that PSI transcript levels and translation rates of proteins, which belong to PSI, are normal in hcf101. PSI‐specific fluorescence at 77 K is shifted from 735 to 728 nm in hcf101, indicating that exitons cannot efficiently be transferred to the PSI reaction centre, whereby the PSI antenna is almost unaffected. Mutant plants not only fail to accumulate mature PSI, which contains three [4Fe‐4S]clusters (FSCs), but also are characterized by reduced levels of the soluble FSC‐containing complex ferredoxin‐thioredoxin reductase (FTR) in the stroma. Inhibited FTR maturation is not a secondary effect stemming from lack of PSI because the mutant hcf145, which also lacks PSI, accumulates FTR at normal levels. Levels of the [2Fe‐2S] cluster‐containing soluble and membrane proteins, ferredoxin and PetC, respectively, were unchanged in hcf101 plants. These data suggest a specific role of HCF101 in FSC biogenesis. HCF101 is plastid localized and belongs to an ancient and universally conserved family of P‐loop ATPases previously designated as the ‘MRP’ (metGrelated protein) family. The function identified for HCF101 suggests a new designation, FSC, for this family.
Involvement of the R2R3‐MYB, AtMYB61, in the ectopic lignification and dark‐photomorphogenic components of the det3 mutant phenotype
Authors: Newman Lisa J. , Perazza Daniel E. , Juda Lusanda , Campbell Malcolm M.
Published: October 2010

Overexpression of a pine MYB, PtMYB4, in Arabidopsis caused ectopic lignin deposition and allowed the plants to undergo photomorphogenesis even when they were grown in the dark. The phenotype caused by PtMYB4 overexpression was reminiscent of the previously characterised dark‐photomorphogenic mutant, de‐etiolated 3 (det3); consequently, we tested the hypothesis that MYB misexpression may explain aspects of the det3 phenotype. We show here that AtMYB61, a member of the Arabidopsis R2R3‐MYB family, is misexpressed in the det3 mutant. Semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR) experiments suggested that AtMYB61 was misexpressed in a det3 background relative to wild‐type plants. Examination of AtMYB61 promoter activity in a det3 background showed that the spatial control of AtMYB61 expression was lost. In order to determine if such misexpression could explain the mutant phenotype, AtMYB61 was overexpressed in wild‐type Arabidopsis plants. Transgenic plants that overexpressed AtMYB61 had the same ectopic lignification and dark‐photomorphogenic phenotype as that of the det3 mutant. In order to test if AtMYB61 was necessary for these aspects of the det3 phenotype, AtMYB61 expression was downregulated in det3 plants in both antisense and sense suppression experiments. Suppression of AtMYB61 in a det3 mutant background restored all mutant phenotypes of the det3 mutant associated with development in the dark. Taken together, these results suggest that AtMYB61 misexpression was both sufficient and necessary to explain the ectopic lignification and dark‐photomorphogenic phenotypes of the det3 mutant.
Salicylic acid regulates flowering time and links defence responses and reproductive development
Authors: Martínez Cristina , Pons Elsa , Prats Guillermo , León José
Published: October 2010

Flowering relies on signaling networks that integrate endogenous and external cues. Normally, plants flower at a particular season, reflecting day length and/or temperature cues. However, plants can surpass this seasonal regulation and show precocious flowering under stress environmental conditions. Here, we show that UV‐C light stress activates the transition to flowering in Arabidopsis thaliana through salicylic acid (SA). Moreover, SA also regulates flowering time in non‐stressed plants, as SA‐deficient plants are late flowering. The regulation of flowering time by SA seems to involve the photoperiod and autonomous pathways, but it does not require the function of the flowering time genes CONSTANS (CO), FCA, or FLOWERING LOCUS C (FLC).
Two functionally different vacuoles for static and dynamic purposes in one plant mesophyll leaf cell
Authors: Epimashko Svetlana , Meckel Tobias , Fischer‐Schliebs Elke , Lüttge Ulrich , Thiel Gerhard
Published: October 2010

It is a common belief that plant mesophyll cells are occupied up to 95% by a single multipurpose vacuole. The common ice plant, Mesembryanthemum crystallinum L., however, requires two contrasting functions of the vacuole under salt stress. Large amounts of NaCl have to be sequestered permanently for osmotic purpose and for protecting the cytoplasm from NaCl toxicity. A dynamic exchange with the cytoplasm is required because photosynthesis proceeds under these conditions via the metabolic cycle of crassulacean acid metabolism (CAM). Nocturnally acquired CO2 must be kept as malate in the vacuole and re‐mobilized in the daytime. Here, we show that two large independent types of vacuoles with different transport properties meet the requirements for the contrasting functions within the same cell.
Cross‐species microarray transcript profiling reveals high constitutive expression of metal homeostasis genes in shoots of the zinc hyperaccumulator Arabidopsis halleri
Authors: Becher Martina , Talke Ina N. , Krall Leonard , Krämer Ute
Published: October 2010

Arabidopsis halleri ssp. halleri (accession Langelsheim) is a naturally selected zinc (Zn)‐ and cadmium‐tolerant Zn hyperaccumulator. This plant differs strikingly from its close relative A. thaliana by accumulating Zn specifically in above‐ground tissues. A. thaliana GeneChips were used in order to identify, on a transcriptome‐wide scale, genes with a potential involvement in cellular metal uptake or detoxification in the shoots of A. halleri. Compared to A. thaliana, transcript abundance of several genes was found and confirmed to be substantially higher in A. halleri after 4 days of exposure to low as well as high Zn concentrations in the hydroponic culture medium. The identified candidate genes encode proteins closely related to the following A. thaliana proteins: AtZIP6, a putative cellular Zn uptake system and member of the zinc‐regulated transporter (ZRT)‐iron regulated transporter (IRT)‐like protein (ZIP)‐family of metal transporters, the putative P‐type metal ATPase AtHMA3, the cation diffusion facilitator ZAT/AtCDF1, and the nicotianamine synthase AtNAS3. Heterologous expression in mutant strains of the yeast Saccharomyces cerevisiae suggested that AhHMA3, AhCDF1‐3, and AhNAS3 can function in cellular Zn detoxification. Our data indicate that, at the transcript level, the Zn tolerance strategy of A. halleri involves high constitutive expression of metal homeostasis genes in the shoots to accommodate higher basal levels of Zn accumulation, and possibly to prepare for sudden increases in Zn influx into shoot cells. Furthermore, profiling of metal homeostasis gene transcripts in shoot and root tissues by real‐time RT‐PCR indicated that A. halleri and A. thaliana respond differently to changes in plant Zn status.
Comparative microarray analysis ofArabidopsis thalianaandArabidopsis halleriroots identifies nicotianamine synthase, a ZIP transporter and other genes as potential metal hyperaccumulation factors
Authors: Weber Michael , Harada Emiko , Vess Christoph , Roepenack‐Lahaye Edda v. , Clemens Stephan
Published: October 2010

The hyperaccumulation of zinc (Zn) and cadmium (Cd) is a constitutive property of the metallophyteArabidopsis halleri. We therefore usedArabidopsisGeneChips to identify genes more active in roots ofA. hallerias compared toA. thalianaunder control conditions. The two genes showing highest expression inA. halleriroots relative toA. thalianaroots out of more than 8000 genes present on the chip encode a nicotianamine (NA) synthase and a putative Zn2+uptake system. The significantly higher activity of these and other genes involved in metal homeostasis under various growth conditions was confirmed by Northern and RT‐PCR analyses.A. halleriroots also show higher NA synthase protein levels. Furthermore, we developed a capillary liquid chromatography electrospray ionization quadrupole time‐of‐flight mass spectrometry (CapLC‐ESI‐QTOF‐MS)‐based NA analysis procedure and consistently found higher NA levels in roots ofA. halleri. Expression of a NA synthase in Zn2+‐hypersensitiveSchizosaccharomyces pombecells demonstrated that formation of NA can confer Zn2+tolerance. Taken together, these observations implicate NA in plant Zn homeostasis and NA synthase in the hyperaccumulation of Zn byA. halleri. Furthermore, the results show that comparative microarray analysis of closely related species can be a valuable tool for the elucidation of phenotypic differences between such species.
Neurodevelopmental outcome of very low birth weight babies admitted to a Malaysian nursery
Authors: Ho JJ , Amar HSS , Mohan AJ , Hon TH
Published: October 2010

Objective: To examine the prevalence and pattern of neurodevelopmental handicap at 2 years of age in very low birth weight infants (VLBW) admitted in 1993 to a level 3 Malaysian nursery.

Methods: All VLBW babies born in the hospital or referred for neonatal care during 1993 were enrolled prospectively in the study. At 2 years of age development was assessed using the Griffiths mental scales. Neurological, hearing and visual assessments were graded into five groups according to functional handicap. Control infants were randomly selected during attendance at a primary health care clinic.

Results: One hundred and fifty VLBW infants were admitted and 82 (54.6%) survived to 2 years, of whom 77 (93.9%) were assessed. The mean General Quotient (GQ) on the Griffiths Scales was 94 (15.7) for the study group and 104 (8.3) for the 60 controls. For GQ, 21 (27.3%) of the study population were 1 or more SD below the mean (18 between 1 and 2 SD and 3 > 2 SD) compared with 1 (1.6%) of the controls who was 1–2 SD below the mean. Visual impairment occurred in 2 study infants and none of the controls. There was no hearing impairment in either group. Cerebral palsy occurred in 3 (1 mild and 2 moderate‐severe) of the study group and none of the controls. Functionally 18 (23.3%) of the study group had mild handicap, 1 (1.3%) moderate, 2 (2.5%) severe, 2 (2.5%) multiply severe and 54 (70.2%) were normal.

Conclusion: Although survival was low, overall rates of functional handicap were similar to those reported in developed countries but the proportion with moderate or severe handicap was low.
Randomised clinical trial of a group parent education programme for Australian Indigenous families
Authors: Turner Karen MT , Richards Mary , Sanders Matthew R
Published: October 2010

Aim:  Parenting programmes have been shown to improve children’s adjustment and reduce problem behaviour; however, little research has addressed outcomes for Indigenous families. The aim of this project was to assess the impact and cultural appropriateness of a parenting programme tailored for Indigenous families, an adaptation of the evidence‐based Group Triple P – Positive Parenting Program.

Methods:  A repeated measures randomised group design methodology was used, comparing the intervention with a waitlist control condition pre‐ and post‐intervention, with a 6‐month follow‐up of the intervention group.

Results:  Parents attending Group Triple P reported a significant decrease in rates of problem child behaviour and less reliance on some dysfunctional parenting practices following the intervention in comparison to waitlist families. The programme also led to greater movement from the clinical range to the non‐clinic range for mean child behaviour scores on all measures. Effects were primarily maintained at 6‐month follow‐up. Qualitative data showed generally positive responses to the programme resources, content and process. However, only a small number of waitlist families subsequently attended groups, signalling the importance of engaging families when they first make contact, helping families deal with competing demands, and offering flexible service delivery so families can resume contact when circumstances permit.

Conclusions:  This study provides empirical support for the effectiveness and acceptability of a culturally tailored approach to Group Triple P conducted by Child Health and Indigenous Health workers in a community setting. The outcomes of this trial may be seen as a significant step in increasing appropriate service provision for Indigenous families and reducing barriers to accessing available services in the community.
Occurrence of subclinical post‐streptococcal glomerulonephritis in family contacts
Authors: Tasic V , Polenakovic M
Published: October 2010

Objective:  There are few data in the published literature on the occurrence of subclinical post‐streptococcal glomerulonephritis. In order to estimate the incidence of subclinical disease, 75 families of index cases with sporadic clinical post‐streptococcal glomerulonephritis were screened for the presence of subclinical disease.

Methods:  Three hundred and seventeen family contacts were investigated 1−7 days after the admission of the index cases. The diagnosis of subclinical disease was based on the presence of abnormal urinalysis, transitory hypocomplementaemia and increased antistreptolysin O titre.

Results:  No cases of clinical/subclinical disease were detected among 147 parents. Abnormal urinalyses were found in 22.3% of sibling contacts. The incidence of nephritis among 170 siblings was 9.4% and the calculated ratio subclinical/clinical disease was 0.11. There were 16 siblings (9.4%) whose abnormal urinalyses could not be explained by appropriate tests; 11 of them had dysmorphic microhaematuria and significantly elevated antistreptolysin O titre.

Conclusions:  Sibling contacts have increased risk for the development of clinical/subclinical post‐streptococcal glomerulonephritis compared with their parents. Sibling contacts with unexplained urinary abnormalities might have subclinical nephritis in evolution; their complement levels normalized before occurrence of nephritis in index cases.
Ultrasound grading of cerebral ventricular dilatation in preterm neonates
Authors: Grasby DC , Esterman A , Marshall P
Published: October 2010

Objective:  To compare three grading systems previously described for the measurement of cerebral ventricular dilatation in preterm neonates using ultrasound scans and then to compare these with expert clinical judgement.

Methods:  Eighty‐one preterm neonates <1500 g birthweight or < 32 weeks’ gestation, with normal, mild, moderate or severely dilated ventricles recorded predominantly during the first 2 weeks of life were selected to ensure a broad representation of ventricular size. Their cranial ultrasound scans obtained nearest to 6 weeks of age were studied. The ventricular index, the diagonal width in the coronal plane and the ventricular height in the parasagittal plane were measured adjacent to the foramen of Monro and were used to grade the degree of dilatation. In 20 of these neonates, this grading was compared with grading based on expert clinical judgement.

Results:  Grading according to the ventricular index defined 79% of the scans as normal. However, only 44% and 39% were considered to be normal according to vertical height and diagonal width, respectively. There was a high level of correlation between expert clinical judgement and grading based on ventricular height measurement (r = 0.812; area under receiver operating characteristic (ROC) curve = 0.922) and the diagonal width (r = 0.806; area under ROC curve = 0.935). Ventricular index correlated poorly with clinical judgement (r = 0.298; area under ROC curve = 0.604).

Conclusions:  The measurement of ventricular height and the measurement of diagonal width correlated well with expert clinical judgement. The ventricular index correlated poorly and was less sensitive to mild dilatation. There was no correlation between the ventricular index and the other two measures. The ventricular height and the diagonal width are more appropriate for assessing ventricular dilatation in preterm neonates.
Concurrent HIV infection and neuroblastoma
Authors: Leotta N , Alvaro F , Dalla‐Pozza L , Isaacs D
Published: October 2010

Abstract:  An infant is reported who presented with Pneumocystis carinii pneumonia, secondary to HIV infection, diagnosed at 3 months of age, and who had concurrent paravertebral neuroblastoma. Although neuroblastoma cell lines support the growth of HIV in vitro, this is the first report of a clinical association between HIV infection and neuroblastoma. Although we do not think the conditions are causally linked, we report the case to raise awareness of a possible association between HIV and neuroblastoma. The case also raises the importance of starting antiretroviral treatment with three drugs.
Systematic review of the role of pre‐oxygenation for tracheal suctioning in ventilated newborn infants
Authors: Pritchard MA , Flenady V , Woodgate P
Published: October 2010

Abstract:  Pre‐oxygenation for endotracheal suctioning for mechanically ventilated infants is routine practice in many neonatal intensive care units. In the present systematic review the evidence to support its use is discussed and the authors conclude that no confident recommendations can be made from the results of this review.
Peak inspiratory flows in children with cystic fibrosis
Authors: Gauld LM , Briggs K , Robinson P
Published: October 2010

Objective:  To show that in children with moderately severe cystic fibrosis lung disease: (i) inspiratory flow may be reduced; and (ii) peak inspiratory flow may be predicted from height, expiratory flow analysis or body mass index.

Methods:  All children attending the Royal Children's Hospital, Melbourne, between May and July, 2001 who had cystic fibrosis, were aged > 5 years, were able to perform spirometry reproducibly and who had a forced expiratory volume in 1 s < 60% predicted were prospectively enrolled. Height, weight, peak inspiratory flow, forced expiratory volume in 1 s and forced vital capacity were recorded. Linear regression analysis was performed.

Results:  The age range was 9.4−19.9 years. Sixteen boys and 11 girls were studied. All children had a peak inspiratory flow > 0.5 L/s. There was a significant relationship between peak inspiratory flow and forced vital capacity (R2 = 0.50) especially in boys (R2 = 0.65). In boys, peak inspiratory flow was significantly related to forced expiratory volume in 1 s (R2 = 0.47). There was no relationship between peak inspiratory flow and predicted values of expiratory flow, age, height, weight or body mass index. Logistic regression was used to predict the probability that peak inspiratory flow was < 2.0 L/s for a given forced vital capacity. If the forced vital capacity is > 2.5 L, peak inspiratory flow is likely to be > 2.0 L/s.

Conclusions:  In children with significant cystic fibrosis lung disease, peak inspiratory flow is likely to be > 0.5 L/s, which is required to activate dry powder inhalers. If the forced vital capacity is < 2.5 L, the peak inspiratory flow may be < 2.0 L/s, and a metered dose inhaler and spacer should be considered. Further studies that investigate the relationship between expiratory flow and peak inspiratory flow against an internal resistance are needed.
Is pentoxifylline therapy effective for the treatment of acute rheumatic carditis? A pilot study
Authors: Narin N , Karakukcu M , Narin F , Akcakus M , Erez R , Halici C
Published: October 2010

Objective:  The aim of the present study was to determine whether pentoxifylline has a beneficial effect on the treatment of rheumatic carditis.

Methods:  A total of 33 children between the ages 6 and 16 were studied in two groups. The first group (5 boys, 10 girls, mean age: 12.2 ± 2.9 years) was treated with steroid plus pentoxifylline and the second group (6 boys, 12 girls, mean age; 11.6 ± 2.8 years) was treated with steroid only for 3−6 weeks until the acute‐phase reactants became normal. At admission and on the 7th, 30th, and 90th days of the treatment, laboratory studies including white blood cell count, erythrocyte sedimentation rate, C‐reactive protein, throat culture and cytokines (interleukin‐1α, tumour necrosis factor‐α) were performed. Cardiac evaluation with chest X‐ray, electrocardiography and echocardiography was performed in all patients. In the control group (12 boys, 3 girls, mean age; 10.7 ± 3.2 years) all parameters were evaluated once only.

Results:  In both groups, the similar white blood cell count was significantly decreased on the 90th day, and there was no significant difference between the two groups. C‐reactive protein, erythrocyte sedimentation rate and interleukin‐1α were significantly decreased on the 30th and 90th days. In the first group (treated with steroid plus pentoxifylline), the cardiothoracic index was significantly greater at the beginning of the therapy. In the first group, tumour necrosis factor‐α became normal on the 30th day and in the second group, tumour necrosis factor‐α became normal on the 7th day of therapy. For all parameters, there was no significant difference between the two groups with respect to the type of therapy used.

Conclusion:  The present study showed that pentoxifylline plus steroid treatment has no beneficial effects on the treatment of acute rheumatic carditis when compared with steroid alone.
Cutaneous lymphadenoma
Authors: Inalöz HS , Chowdhury MMU , Knight AG
Published: October 2010

Lymphoepithelial neoplasms are biphasic tumours that contain both epithelial and lymphoid components. This heterogeneous group includes benign cutaneous lymphadenoma (CL), malignant lymphoepithelioma‐like carcinoma of the skin and dermal thymus. We present two cases of CL in male subjects of 14 and 64 years of age. The latter man had a history of multiple basal cell carcinomas (BCCs) and solar keratoses. Histological sections of both tumours revealed similar features of an invasive non‐ulcerated tumour with a mixed architecture of BCC and trichoepithelioma. Immunocytochemical examination revealed a biphasic epithelial tumour of follicular differentiation, possibly a variant of trichoepithelioma or a BCC. Within the epithelial islands there was a heavy infiltration that was confirmed as CD3‐positive T cells and S‐100‐positive dendritic cells by immunocytochemistry.
Gene Flow and Genetic Restoration: The Florida Panther as a Case Study
Authors: HEDRICK PHILIP W.
Published: October 2010

Abstract: Populations of some endangered species have become so small that they have lost genetic variation and appear to have become fixed for deleterious genetic variants. To avoid extinction from this genetic deterioration individuals from related subspecies or populations may have to be introduced for genetic restoration i.e., elimination of deleterious variants and recovery to a normal level of genetic variation. I construct a general population genetics framework from which to evaluate the potential for genetic restoration, and I discuss its specific application to the Florida panther. The translocation of Texas cougars into the free‐ranging Florida panther population has been recommended to genetically restore the Florida panther, a subspecies of Felis concolor that appears to have both a low level of genetic variation and low fitness. Specific recommendations recently given by a scientific panel are to introduce enough animals so that there is approximately 20% gene flow in the first generation of translocation and approximately 2–4% in the generations thereafter. I evaluated these recommendations in a theoretical population genetics framework and found that they should result in the removal of most detrimental genetic variation and an increase in the standing genetic variation without a high probability of loss of any adaptive Florida panther alleles. Unless the population of the free‐ranging Florida panthers is very small, the planned translocation should result in genetic restoration of the Florida panther.

Flujo de genes y restauractión: La pantera de la Florida como un estudio de caso
Landscape Characteristics of Fragmented Shrubsteppe Habitats and Breeding Passerine Birds
Authors: KNICK STEVEN T. , ROTENBERRY JOHN T.
Published: October 2010

Abstract: We examined the influence of local and landscape‐level attributes of fragmented habitats in shrubsteppe habitats on the breeding distributions of Sage (Amphispiza belli) and Brewer's (Spizella breweri) Sparrows, Sage Thrashers (Oreoscoptes montanus), Horned Larks (Eremophila alpestris), and Western Meadowlarks (Sturnella neglecta) in the Snake River Plains of southwestern Idaho. We developed habitat (resource) selection models for each species by combining bird counts conducted from 1991 through 1933 with local vegetation characteristics and landscape attributes derived from satellite imagery. Site selection by shrubsteppe species (Sage and Brewer's Sparrows, and Sage Thrashers) depended on local vegetation cover and landscape features, such as the patch size of shrub habitats or the spatial similarity of sites. Marginal sites for these species (with species present in one of three years) were intermediate between unoccupied (never present) and occupied sites along environmental gradients characterized by increasing size of shrub habitat patches and total shrub cover and by decreasing disturbance. Horned Larks and Western Meadowlarks, typical grassland species, were not sensitive to landscape features, and their occupancy depended on the amount of grassland or shrub cover. In contrast to shrubsteppe species, sites that varied by occupancy rates of Western Meadowlarks did not significantly differ in vegetation or landscape components. Our results demonstrate that fragmentation of shrubsteppe significantly influenced the presence of shrub‐obligate species. Because of restoration difficulties, the disturbance of semiarid shrubsteppe may cause irreversible loss of habitat and significant long‐term consequences for the conservation of shrub‐obligate birds.

Características del paisaje en ambientes fragmentados de estepas arbustivas y pájaros paserínidos en estado reproductivo
Effects of Patch Size on Birds in Old‐Growth Montane Forests
Authors: SCHIECK JIM , LERTZMAN KEN , NYBERG BRIAN , PAGE RICK
Published: October 2010

Abstract: Following habitat alteration or fragmentation, competition, parasitism, and predation from species that live in the new habitats may reduce the survival and reproductive success of species living in the original habitats. Negative influences from species that live outside the remnant patches are expected to be greater in small rather than in large remnant patches because more “external” species are expected to move through the centers of small remnant patches. We surveyed birds within remnant patches of old‐growth montane forests on Vancouver Island, Canada, (1) to evaluate whether the richness and abundance of non‐old‐growth bird species were larger at the center of small rather than large patches and (2) to evaluate whether the opposite was true of old‐growth bird species. More non‐old‐growth bird species were present at the center of small remnant patches of old growth than in large old‐growth patches. We found no relationship, however, between patch size and richness or abundance of old‐growth bird species at the center of remnant patches of old growth. This was true for old‐growth species with open, cup‐shaped nests and cavity nests. Old‐growth birds may have been affected less in our study area than in other areas because they evolved within heterogeneous montane forests and interacted with non‐old‐growth species throughout their evolutionary histories or because the contrast between old‐growth forests and logged areas was less than that between the forests and agricultural/urban areas that were surveyed in other studies.

Efectos del tamaño de parches sobre las aves en bosques primarios de montaña
Effects of Forest Fragmentation on Understory Hummingbirds in Amazonian Brazil
Authors: STOUFFER PHILIP C. , BIERREGAARD RICHARD O.
Published: October 2010

Abstract:We sampled understory bummingbirds in Amazonian forest fragments from before isolation through nine years after isolation. We recorded 377 captures of eight species in five 1‐ba fragments and four 10‐ha fragments. The three species netted before isolation, Phaethornis superciliosus, Phaethornis bourcieri,andThalurania furcata,were nearly equally abundant at that time. After isolation abundance ofP. bourcieriandT. furcatadid not change, butP. superciliosusbecame nearly twice as common. Five additional species that were netted only after isolation represented about 10% of the post‐isolation sample. The species recorded only after isolation were forest species usually found above the levels of nets; fragments were not colonized by nonforest species. Use of fragments did not differ between 1‐and 10‐ba fragments. The landscape surrounding the fragments included active cattle pasture, abandoned pasture, andCecropia‐dominated second growth, but this variation bad little effect on use of fragments by hummingbirds. The results suggest that these understory hummingbirds can persist in a matrix of fragments, secondary growth, and large forest patches. This response is much different than that of the insectivorous birds that dominate the understory bird community at the site, which are much more vulnerable to fragmentation.

Efectos de la fragmentación del bosque sobre los colibrís de sotobosque en la Amazonia Brasileña
The Long‐Term Effects of Tiger Poaching on Population Viability
Authors: KENNEY JOHN S. , SMITH JAMES L. D. , STARFIELD ANTHONY M. , MCDOUGAL CHARLES W.
Published: October 2010

Abstract: Poaching tigers, primarily for their bones, has become the latest threat to the persistence of wild tiger populations throughout the world. Anecdotal information indicates the seriousness of this new threat. It is important, however, to provide a quantitative analysis of poaching as a basis for strong policy action. We therefore created a tiger simulation model to explore the effects of realistic levels of poaching on population viability. The model is an individually based, stochastic spatial model that is based on the extensive data set from Royal Chitwan National Park, Nepal. We found that as poaching continues over time, the probability of population extinction increases sigmoidally; a critical zone exists in which a small, incremental increase in poaching greatly increases the probability of extinction. The implication is that poaching may not at first be seen as a threat but could suddenly become one. Moreover, even if poaching is effectively stopped, tiger populations will still be vulnerable and could go extinct due to demographic and environmental stochasticity. Our model also shows that poaching reduces genetic variability, which could further reduce population viability due to inbreeding depression. The longer poaching is allowed to continue, the more vulnerable a population will be to these stochastic events. At currently reported rates of poaching our analysis indicates that many wild tiger populations will be extirpated during the latter half of the 1990s.

Los efectos a largo plazo de la caza furtiva de tigres sobre la viabilidad poblacional
A Conservation Gap Analysis of Brazil's Amazonian Vegetation
Authors: FEARNSIDE PHILIP M. , FERRAZ JOÃO
Published: October 2010

Abstract: Vegetation types lacking protection in the existing conservation units of the nine states in the Brazilian Legal Amazon were identified, and locations were noted where these vegetation types could be protected. Maps of vegetation, protected areas, and semi‐protected areas, such as Amerindian and forestry reserves, were digitized and overlaid using a geographic information system. There are 28 natural vegetation types in the Brazilian Legal Amazon. Locations of new areas for protection were selected using a minimum criterion of protecting at least one example of each vegetation type in each state (here called “vegetation zones”). There are 111 vegetation zones in the Legal Amazon, of which only 37 (33%) have some portion of their area protected. There are few protected areas in the most heavily deforested states along the southeastern fringe of the forest. In Maranhão, where 60% of the original forest had been lost by 1990, only one of 10 vegetation types is protected. Negotiating agreements with indigenous tribes, and to a lesser extent with extractivists who harvest nontimber products from the forest, represents a major opportunity to increase significantly the area and representativeness of the conservation units. Additional conservation units need to be established quickly before rapidly increasing deforestation and land prices preclude this opportunity; otherwise, some vegetation types may virtually disappear.

Un análisis de conservación de la vegetación Amazónica del Brasil
Tree‐Dependent Lichens and Beetles as Indicators in Conservation Forests
Authors: NILSSON SVEN G. , ARUP ULF , BARANOWSKI RICKARD , EKMAN STEFAN
Published: October 2010

Abstract: We tested whether the conspicuous lichen Lobaria pulmonaria indicates the number of tree‐dependent, red‐listed species in a hemiboreal forest in southern Sweden. In 18 naturally regenerated, mainly old deciduous forest plots considered to be of high or very high conservation value, the number of red‐listed tree lichens or wood beetles was not positively correlated with the area of the forest stands studied (8–56 ha). The 8 stands with L. pulmonaria had about nine (median) red‐listed lichens, but 10 stands without L. pulmonaria had only about one such species, a highly significant difference. Similarly, the variation between stands in the number of red‐listed wood beetles was considerable, but it was very weakly correlated with the number of red‐listed lichens. The number of red‐listed wood beetles dependent on dead trees was not different in areas with or without Lobaria pulmonaria, but the number of red‐listed wood beetles dependent on hollow trees was higher in stands with Lobaria pulmonaria (median of seven species) than in those without (three species) the lichen. Stands with this lichen species also contained significantly more of other types of lichens that have been proposed as indicators of forest continuity according to three lists. We stress the need for identification of species that could serve as indicators of different types of forest continuity and identify some organism groups that may indicate the different types.

Los líquenes y coleópteros dependientes de árboles como indicadores en los bosques bajo conservación
Genetic Estimates of Variability and Relatedness for Conservation of an Ozark Cave Crayfish Species Complex
Authors: KOPPELMAN JEFFREY B. , FIGG DENNIS E.
Published: October 2010

Abstract: Allozyme‐based genetic distances were used to determine the distinctness of six species of cave crayfish from the Ozark Plateau in Missouri, Arkanasa, and Oklahoma. One of the cave species is in the subgenus Erebicambarus and the others are in Jugicambarus. Four of the six species are very rare and are found in only one to three known sites each. In addition, most populations of all the species are presumed to be small; rarely are more than a few individuals observed. A chela (claw) was collected from sixty individuals representing the six species, including all known populations of the four rare species. Variability and distance estimates were based on 20 presumptive gene loci. Populations samples with identical genotypes were pooled. Thirteen loci were polymorphic, but average heterozygosity was low (H = 1%) compared to epigean crayfish species. Pairwise genetic distances within Jugicambarus ranged from D = 0.051 to 0.522, and mean distance between subgenera was D = 0.676. The underground water systems in Ozark caves are defined by discreet recharge zones. Groundwater pollution threatens the stability of cave ecosystems, including the survival of cave crayfish. If restoration of threatened or extirpated populations becomes necessary, a database genetic variability and relatedness estimates for known populations of all the species will aid decisions about numbers and sources of individuals for propagation or transfer.

Tolerancia a la hipoxia en cíclidos del Africa oriental: Refugios con bajo contenido de oxígeno en el lago Victoria
Melt loss and the preservation of granulite facies mineral assemblages
Authors: White R. W. , Powell R.
Published: October 2010

The loss of a metamorphic fluid via the partitioning of H2O into silicate melt at higher metamorphic grade implies that, in the absence of open system behaviour of melt, the amount of H2O contained within rocks remains constant at temperatures above the solidus. Thus, granulite facies rocks, composed of predominantly anhydrous minerals and a hydrous silicate melt should undergo considerable retrogression to hydrous upper amphibolite facies assemblages on cooling as the melt crystallizes and releases its H2O. The common occurrence of weakly retrogressed granulite facies assemblages is consistent with substantial melt loss from the majority of granulite facies rocks. Phase diagram modelling of the effects of melt loss in hypothetical aluminous and subaluminous metapelitic compositions shows that the amount of melt that has to be removed from a rock to preserve a granulite facies assemblage varies markedly with rock composition, the number of partial melt loss events and the P–T conditions at which melt loss occurs. In an aluminous metapelite, the removal of nearly all of the melt at temperatures above the breakdown of biotite is required for the preservation of the peak mineral assemblage. In contrast, the proportion of melt loss required to preserve peak assemblages in a subaluminous metapelite is close to half that required for the aluminous metapelite. Thus, if a given proportion of melt is removed from a sequence of metapelitic granulites of varying composition, the degree of preservation of the peak metamorphic assemblage may vary widely.
Thermal‐baric structure andP–Thistory of the Brooks Range metamorphic core, Alaska
Authors: Vogl J. J.
Published: October 2010

Documentation of pressure–temperature (P–T) histories across an epidote‐amphibolite facies culmination provides new insight into the tectono‐thermal evolution of the Brooks Range collisional orogen. Thermobarometry reveals that the highest grade rocks formed at peak temperatures of 560–600 °C and at pressures of 8–9.5 kbar. The thermal culmination coincides with the apex of a structural dome defined by oppositely dipping S2 crenulation cleavages suggesting post‐metamorphic doming. South of the thermal culmination, greenschist facies and lowermost epidote‐amphibolite facies rocks preserve widespread evidence for an early blueschist facies metamorphism. In contrast, no evidence for an early blueschist facies metamorphism was found in similar grade rocks of the northern flank, indicating that the southern flank underwent initial deeper burial during southward underthrusting of the continental margin. Thus, while the dome shows a symmetric distribution of peak temperatures, theP–Tpaths followed by the two flanks must have varied. This variation suggests that final thermal re‐equilibration to greenschist and epidote–amphibolite facies conditions did not result from a simple process of southward underthrusting followed by thermal re‐equilibration from the bottom upward. The new data are inconsistent with a previous model that invokes such re‐equilibration, along with northward thrusting of epidote–amphibolite facies rocks over lower grade rocks presently on the southern flank of the culmination, to produce an inverted metamorphic field gradient. Instead, it is suggested that following blueschist facies metamorphism, rocks of the southern and northern flanks were juxtaposed, during which time the more deeply buried south flank was partially emplaced above rocks to the north, where they escaped Albian epidote–amphibolite facies overprinting. Porphyroblast growth, which post‐dates the main fabric on the north flank of the culmination may be the result of Albian thermal re‐equilibration following this deformation. Post‐metamorphic doming resulted from a combination of Albian‐Cenomanian extension and Tertiary deformation.
The metamorphic evolution of metapelitic granulites from Radok Lake, northern Prince Charles Mountains, east Antarctica; evidence for an anticlockwise P–T path
Authors: Boger S. D. , White R. W.
Published: October 2010

Mineral textures in metapelitic granulites from the northern Prince Charles Mountains, coupled with thermodynamic modelling in the K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 (KFMASHTO) model system, point to pressure increasing with increasing temperature on the prograde metamorphic path, followed by retrograde cooling (i.e. an anticlockwise P–T path). Textural evidence for the increasing temperature part of the path is given by the breakdown of garnet and biotite to form orthopyroxene and cordierite in sillimanite‐absent rocks, and through the break‐down of biotite and sillimanite to form spinel, cordierite and garnet in more aluminous assemblages. This is equated to the advective addition of heat from the regional emplacement of granitic and charnockitic magmas dated at c. 980 Ma. A subsequent increase in pressure, inferred from the break‐down of spinel and quartz to sillimanite, cordierite and garnet in aluminous rocks, is attributed to crustal thickening related to upright folding dated at 940–910 Ma. The terrane attained peak metamorphic temperatures of c. 880 °C at pressures of c. 6.0–6.5 kbar during this event. Subsequent cooling is inferred from the localised breakdown of cordierite and garnet to form biotite and sillimanite that developed in the latter stages of the same event. The textural observations described are interpreted via the application of P–T and P–T–X pseudosections. The latter show that most rock compositions preserve only fragments of the overall P–T path; a result of different rock compositions undergoing mineral assemblage changes, or changes in mineral modal abundance, on different sections of the P–T path. The results also suggest that partial melting during granulite facies metamorphism, coupled with melt loss and dehydration, initiated a switch from pervasive ductile, to discrete ductile/brittle deformation, during retrograde cooling.
Chemical and physical responses to deformation in micaceous quartzites from the Tauern Window, Eastern Alps
Authors: Selverstone J. , Hyatt J.
Published: October 2010

Micaceous quartzites from a subvertical shear zone in the Tauern Window contain abundant quartz clasts derived from dismembered quartz‐tourmaline veins. Bulk plane strain deformation affected these rocks at amphibolite facies conditions. Shape changes suggest net shortening of the clasts by 11–64%, with a mean value of 35%. Quartz within the clasts accommodated this strain largely via dislocation creep processes. On the high‐stress flanks of the clasts, however, quartz was removed via solution mass transfer (pressure solution) processes; the resulting change in bulk composition allowed growth of porphyroblastic staurolite + chlorite ± kyanite on the clast flanks. Matrix SiO2 contents decrease from c. 83 wt% away from the clasts to 49–58% in the selvages on the clast flanks. The chemical changes are consistent with c. 70% volume loss in the high‐stress zones. Calculated shortening values within the clast flanks are similar to the volume‐loss estimates, and are greatly in excess of the shortening values calculated from the clasts themselves. Flow laws for dislocation creep versus pressure solution imply large strain‐rate gradients and/or differential stress gradients between the matrix and the clast selvages. In a rock containing a large proportion of semirigid clasts, weakening within the clast flanks could dominate rock rheology. In our samples, however, weakening within the selvages was self limiting: (1) growth of strong staurolite porphyroblasts in the selvages protected remaining quartz from dissolution; and (2) overall flattening of the quartz clasts probably decreased the resolved shear stress on the flanks to values near those of the matrix, which would have reduced the driving force for solution‐transfer creep. Extreme chemical changes nonetheless occurred over short distances. The necessity of maintaining strain compatibility may lead to significant localized dissolution in rocks containing rheologic heterogeneities, and overall weakening of the rocks may result. Solution‐transfer creep may be a major process whereby weakening and strain localization occur during deep‐crustal metamorphism of polymineralic rocks.
The metamorphic field gradient in the eclogite type locality, Koralpe region, Eastern Alps
Authors: Tenczer V. , Stüwe K.
Published: October 2010

The eclogite type locality in the Eastern Alps (the Koralpe and Saualpe region) is the largest region in the Eastern Alps that preserves high‐pressure metamorphic rocks from the Eo‐Alpine orogenic event of the Cretaceous age. Thermobarometric data from the metapelitic gneisses in the region indicate that a metamorphic field gradient across the region can be divided into three parts. The northern part shows continuously increasing P–T from 10 ± 1.5 to 14 ± 1.5 kbar and 500 ± 68 to 700 ± 68 °C over a distance of 40 km. The continuous increase in P–T indicates that no major tectonic boundaries were active in this part during the Eo‐Alpine orogeny. Small discontinuities in the pressure gradient of the northern part can be correlated with more localized deformation. The central part exposes amphibolite–eclogite facies rocks with 15 ± 1.5 kbar and 700 ± 68 °C over about 20 km length. The southern part shows decreasing P–T conditions from 15 ± 1.5 to 10 ± 1.5 kbar and 700 ± 68 to 600 ± 63 °C over a distance of 10 km beyond which conditions remain roughly constant for the remainder of the profile.

Overall, the field gradient is characterized by: (i) an increase in age with decreasing metamorphic grade and (ii) a T/P ratio that is lower than common metamorphic geotherms. The age–grade relationship is consistent with the timing relationship along piezothermal arrays predicted by simple models for regional metamorphism. However, the T/P ratio of the field gradient is inconsistent with such an interpretation. These inconsistencies indicate that the profile is not simply an obliquely exposed crustal section. We suggest that the exhumation of the transect is best explained with a two dimensional model of an extruding wedge, as has recently been suggested as a typical scenario for other large scale compressional orogens.