bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation Study for the Series Connected Bundles of Microtubular SOFCs
Authors: Funahashi Yoshihiro , Shimamori Toru , Suzuki Toshio , Fujishiro Yoshinobu , Awano Masanobu , Araki Takuto
Published: July 2010

Solid oxide fuel cells (SOFCs) have the highest energy conversion efficiency among various power generators and expected to be earlier commercialization. Our study aims to develop fabrication techniques of microtubular SOFC bundles and establish realistic bundle structure for kilowatt class module. So far, we have succeeded to establish fabrication technology of the microtubular SOFC bundles using porous supporting matrices. In this study, the simulation study of the microtubular SOFC bundle was carried out to understand Joule heat and temperature distribution in the microtubular SOFC bundle during operation. The results indicated that the method of current collection had to be carefully considered, since the total output power loss of the bundle was estimated to be 27.8%. The temperature distribution of the bundle using porous MgO matrices turned out to be moderate compared with that in the previous bundle using porous (La,Sr)(Co,Fe)O3 matrices due to the difference in the thermal conductivity of each matrix constitute.
Effectiveness and Safety of Tenofovir Gel, an Antiretroviral Microbicide, for the Prevention of HIV Infection in Women
Authors: Abdool Karim Quarraisha , Abdool Karim Salim S. , Frohlich Janet A. , Grobler Anneke C. , Baxter Cheryl , Mansoor Leila E. , Kharsany Ayesha B. M. , Sibeko Sengeziwe , Mlisana Koleka P. , Omar Zaheen , Gengiah Tanuja N. , Maarschalk Silvia , Arulappan Natasha , Mlotshwa Mukelisiwe , Morris Lynn , Taylor Douglas ,   on behalf of the CAPRISA 004 Trial Group
Published: July 2010

Vaginal Gel Versus HIV

HIV prevention technologies for women are urgently needed, especially in sub-Saharan Africa where young women bear the greatest burden of the HIV epidemic.

Abdool Karim
et al.

(p.
1168
; published online 19 July) present the results of the CAPRISA 004 randomized control trial. The nearly 3-year-long trial, conducted in urban and rural South African women, tested the efficacy of a vaginal gel containing the antiretroviral drug tenofovir in preventing HIV infection. The dosing strategy required application of the gel both before and after coitus, and with this regime HIV infection was reduced by approximately 39% overall, by 54% in women with high adherence to the protocol, and with no increase in overall adverse event rates.
It Runs in the Family
Authors: VanHook Annalisa M.
Published: July 2010

Hh signaling in body segment formation suggests that annelids and arthropods may share a common segmented ancestor.
Comment on “Increased MKK4 Abundance with Replicative Senescence Is Linked to the Joint Reduction of Multiple MicroRNAs”
Authors: Moens Ugo , Shiryaev Alexey , Dumitriu Gianina
Published: July 2010

The antibody used to detect phosphorylated PRAK is suspect.
Identification of a Dendrimeric Heparan Sulfate-Binding Peptide That Inhibits Infectivity of Genital Types of Human Papillomaviruses
Authors: Donalisio Manuela , Rusnati Marco , Civra Andrea , Bugatti Antonella , Allemand Donatella , Pirri Giovanna , Giuliani Andrea , Landolfo Santo , Lembo David
Published: July 2010

Peptide dendrimers consist of a peptidyl branching core and/or covalently attached surface functional units. They show a variety of biological properties, including antiviral activity. In this study, a minilibrary of linear, dimeric, and dendrimeric peptides containing clusters of basic amino acids was evaluated for
in vitro
activity against human papillomaviruses (HPVs). The peptide dendrimer SB105-A10 was found to be a potent inhibitor of genital HPV types (i.e., types 16, 18, and 6) in pseudovirus-based neutralization assays. The 50% inhibitory concentration was between 2.8 and 4.2 μg/ml (0.59 and 0.88 μM), and no evidence of cytotoxicity was observed. SB105-A10 interacts with immobilized heparin and with heparan sulfates exposed on the cell surface, most likely preventing virus attachment. The findings from this study indicate SB105-A10 to be a leading candidate compound for further development as an active ingredient of a topical microbicide against HPV and other sexually transmitted viral infections.
The Virucidal EB Peptide Protects Host Cells from Herpes Simplex Virus Type 1 Infection in the Presence of Serum Albumin and Aggregates Proteins in a Detergent-Like Manner
Authors: Bultmann Hermann , Girdaukas Gary , Kwon Glen S. , Brandt Curtis R.
Published: July 2010

The linear cationic amphiphilic EB peptide, derived from the FGF4 signal sequence, was previously shown to be virucidal and to block herpes simplex type I (HSV-1) entry (H. Bultmann, J. S. Busse, and C. R. Brandt, J. Virol. 75:2634–2645, 2001). Here we show that cells treated with EB (RRKKAAVALLPAVLLALLAP) for less than 5 min are also protected from infection with HSV-1. Though protection was lost over a period of 5 to 8 h, it was reinduced as rapidly as during the initial treatment. Below a 20 μM concentration of EB, cells gained protection in a serum-dependent manner, requiring bovine serum albumin (BSA) as a cofactor. Above 40 μM, EB coprecipitated with BSA under hypotonic conditions. Coprecipitates retained antiviral activity and released active peptide. NaCl (≥0.3 M) blocked coprecipitation without interfering with antiviral activity. As shown for β-galactosidase, EB below 20 μM acted as an enzyme inhibitor, whereas above 40 to 100 μM EB, β-galactosidase was precipitated as was BSA or other unrelated proteins. Pyrene fluorescence spectroscopy revealed that in the course of protein aggregation, EB acted like a cationic surfactant and self associated in a process resembling micelle formation. Both antiviral activity and protein aggregation did not depend on stereospecific EB interactions but depended strongly on the sequence of the peptide's hydrophobic tail. EB resembles natural antimicrobial peptides, such as melittin, but when acting in a nonspecific detergent-like manner, it primarily seems to target proteins.
A
Francisella tularensis
Live Vaccine Strain (LVS) Mutant with a Deletion in
capB
, Encoding a Putative Capsular Biosynthesis Protein, Is Significantly More Attenuated than LVS yet Induces Potent Protective Immunity in Mice against
F. tularensis
Challenge
Authors: Jia Qingmei , Lee Bai-Yu , Bowen Richard , Dillon Barbara Jane , Som Susan M. , Horwitz Marcus A.
Published: July 2010

Francisella tularensis
, the causative agent of tularemia, is in the top category (category A) of potential agents of bioterrorism. The
F. tularensis
live vaccine strain (LVS) is the only vaccine currently available to protect against tularemia; however, this unlicensed vaccine is relatively toxic and provides incomplete protection against aerosolized
F. tularensis
, the most dangerous mode of transmission. Hence, a safer and more potent vaccine is needed. As a first step toward addressing this need, we have constructed and characterized an attenuated version of LVS, LVS Δ
capB
, both as a safer vaccine and as a vector for the expression of recombinant
F. tularensis
proteins. LVS Δ
capB
, with a targeted deletion in a putative capsule synthesis gene (
capB
), is antibiotic resistance marker free. LVS Δ
capB
retains the immunoprotective O antigen, is serum resistant, and is outgrown by parental LVS in human macrophage-like THP-1 cells in a competition assay. LVS Δ
capB
is significantly attenuated in mice; the 50% lethal dose (LD
50
) intranasally (i.n.) is >10,000-fold that of LVS. Providing CapB in
trans
to LVS Δ
capB
partially restores its virulence in mice. Mice immunized with LVS Δ
capB
i.n. or intradermally (i.d.) developed humoral and cellular immune responses comparable to those of mice immunized with LVS, and when challenged 4 or 8 weeks later with a lethal dose of LVS i.n., they were 100% protected from illness and death and had significantly lower levels (3 to 5 logs) of LVS in the lung, liver, and spleen than sham-immunized mice. Most importantly, mice immunized with LVS Δ
capB
i.n. or i.d. and then challenged 6 weeks later by aerosol with 10× the LD
50
of the highly virulent type A
F. tularensis
strain SchuS4 were significantly protected (100% survival after i.n. immunization). These results show that LVS Δ
capB
is significantly safer than LVS and yet provides potent protective immunity against virulent
F. tularensis
SchuS4 challenge.
A Decade of
Burkholderia cenocepacia
Virulence Determinant Research
Authors: Loutet Slade A. , Valvano Miguel A.
Published: July 2010

The
Burkholderia cepacia
complex (Bcc) is a group of genetically related environmental bacteria that can cause chronic opportunistic infections in patients with cystic fibrosis (CF) and other underlying diseases. These infections are difficult to treat due to the inherent resistance of the bacteria to antibiotics. Bacteria can spread between CF patients through social contact and sometimes cause cepacia syndrome, a fatal pneumonia accompanied by septicemia.
Burkholderia cenocepacia
has been the focus of attention because initially it was the most common Bcc species isolated from patients with CF in North America and Europe. Today,
B. cenocepacia
, along with
Burkholderia multivorans
, is the most prevalent Bcc species in patients with CF. Given the progress that has been made in our understanding of
B. cenocepacia
over the past decade, we thought that it was an appropriate time to review our knowledge of the pathogenesis of
B. cenocepacia
, paying particular attention to the characterization of virulence determinants and the new tools that have been developed to study them. A common theme emerging from these studies is that
B. cenocepacia
establishes chronic infections in immunocompromised patients, which depend more on determinants mediating host niche adaptation than those involved directly in host cells and tissue damage.
The K1 Capsular Polysaccharide of
Acinetobacter baumannii
Strain 307-0294 Is a Major Virulence Factor
Authors: Russo Thomas A. , Luke Nicole R. , Beanan Janet M. , Olson Ruth , Sauberan Shauna L. , MacDonald Ulrike , Schultz L. Wayne , Umland Timothy C. , Campagnari Anthony A.
Published: July 2010

Acinetobacter baumannii
is a pathogen of increasing medical importance with a propensity to be multidrug resistant, thereby making treatment challenging. Little is known of virulence traits in
A. baumannii
. To identify virulence factors and potential drug targets, random transposon (Tn) mutants derived from the
A. baumannii
strain AB307-0294 were screened to identify genes essential for growth in human ascites fluid
in vitro
, an inflammatory exudative fluid. These studies led to the identification of two genes that were predicted to be required for capsule polymerization and assembly. The first,
ptk
, encodes a putative protein tyrosine kinase (PTK), and the second,
epsA
, encodes a putative polysaccharide export outer membrane protein (EpsA). Monoclonal antibodies used in flow cytometric and Western analyses confirmed that these genes are required for a capsule-positive phenotype. A capsule-positive phenotype significantly optimized growth in human ascites fluid, survival in human serum, and survival in a rat soft tissue infection model. Importantly, the clearance of the capsule-minus mutants AB307.30 (
ptk
mutant, capsule minus) and AB307.45 (
epsA
mutant, capsule minus) was complete and durable. These data demonstrated that the K1 capsule from AB307-0294 was an important protectin. Further, these data suggested that conserved proteins, which contribute to the capsule-positive phenotype, are potential antivirulence drug targets. Therefore, the results from this study have important biologic and translational implications and, to the best of our knowledge, are the first to address the role of capsule in the pathogenesis of
A. baumannii
infection.
Modulation of the Local Neutrophil Response by a Novel Hyaluronic Acid-Binding Peptide Reduces Bacterial Burden during Staphylococcal Wound Infection
Authors: Lee Jerry C. , Greenwich Jennifer L. , Zhanel George G. , Han Xiaobing , Cumming Andrew , Saward Laura , McLoughlin Rachel M.
Published: July 2010

Novel approaches targeting the host's immune response to treatStaphylococcus aureusinfections have significant potential to improve clinical outcomes, in particular during infection with antibiotic-resistant strains. The hyaluronic acid-binding peptide (HABP) PEP35 was assessed for its ability to treatS. aureusinfections using a clinically relevant murine model of surgical wound infection. PEP35 demonstrated no direct antimicrobial activity against a range of antibiotic-susceptible and antibiotic-resistant clinical isolates ofStaphylococcus aureus. However, when this peptide was administered at the onset of infection and up to 4 h postchallenge with a methicillin-susceptible (MSSA) or a methicillin-resistant (MRSA) strain ofS. aureus, it significantly reduced the bacterial burden at the wound infection site. PEP35 reduced the tissue bacterial burden by exclusively modulating the local neutrophil response. PEP35 administration resulted in a significant early increase in local CXCL1 and CXCL2 production, which resulted in a more rapid influx of neutrophils to the infection site. Importantly, neutrophil influx was not sustained after treatment with PEP35, and administration of PEP35 alone did not induce a local inflammatory response. The immunomodulatory effects of PEP35 on CXC chemokine production were TLR2 and NF-κB dependent. We propose a novel role for a HABP as an innate immunomodulator in the treatment of MSSA and MRSA surgical wound infection through enhancement of the local CXC chemokine-driven neutrophil response.
Mutagenesis of Conserved Amino Acids ofHelicobacter pyloriFur Reveals Residues Important for Function
Authors: Carpenter Beth M. , Gancz Hanan , Benoit Stéphane L. , Evans Sarah , Olsen Cara H. , Michel Sarah L. J. , Maier Robert J. , Merrell D. Scott
Published: July 2010

The ferric uptake regulator (Fur) of the medically important pathogenHelicobacter pyloriis unique in that it has been shown to function as a repressor both in the presence of an Fe2+cofactor and in itsapo(non-Fe2+-bound) form. However, virtually nothing is known concerning the amino acid residues that are important for Fur functioning. Therefore, mutations in six conserved amino acid residues ofH. pyloriFur were constructed and analyzed for their impact on both iron-bound andaporepression. In addition, accumulation of the mutant proteins, protein secondary structure, DNA binding ability, iron binding capacity, and the ability to form higher-order structures were also examined for each mutant protein. While none of the mutated residues completely abrogated the function of Fur, we were able to identify residues that were critical for both iron-bound andapo-Fur repression. One mutation, V64A, did not alter regulation of any target genes. However, each of the five remaining mutations showed an effect on either iron-bound oraporegulation. Of these, H96A, E110A, and E117A mutations altered iron-bound Fur regulation and were all shown to influence iron binding to different extents. Additionally, the H96A mutation was shown to alter Fur oligomerization, and the E110A mutation was shown to impact oligomerization and DNA binding. Conversely, the H134A mutant exhibited changes inapo-Fur regulation that were the result of alterations in DNA binding. Although the E90A mutant exhibited alterations inapo-Fur regulation, this mutation did not affect any of the assessed protein functions. This study is the first forH. pylorito analyze the roles of specific amino acid residues of Fur in function and continues to highlight the complexity of Fur regulation in this organism.
Discontinuity and Limited Linkage in the Homologous Recombination System of a Hyperthermophilic Archaeon
Authors: Grogan Dennis W. , Rockwood Jananie
Published: July 2010

Genetic transformation of
Sulfolobus acidocaldarius
by a multiply marked
pyrE
gene provided a high-resolution assay of homologous recombination in a hyperthermophilic archaeon. Analysis of 100 Pyr
+
transformants revealed that this recombination system could transfer each of 23 nonselected base pair substitutions to the recipient chromosome along with the selected marker. In 30% of the recombinants, donor markers were transferred as multiple blocks. In at least 40% of the recombinants, donor markers separated by 5 or 6 bp segregated from each other, whereas similar markers separated by 2 bp did not segregate. Among intermarker intervals, the frequency of recombination tract endpoints varied 40-fold, but in contrast to other recombination systems, it did not correlate with the length of the interval. The average length of donor tracts (161 bp) and the frequent generation of multiple tracts seemed generally consistent with the genetic properties observed previously in
S. acidocaldarius
conjugation. The efficiency with which short intervals of diverged
pyrE
sequence were incorporated into the genome raises questions about the threat of ectopic recombination in
Sulfolobus
spp. mediated by this apparently efficient yet permissive system.
Matched cohort analysis in traffic injury epidemiology: including adults when estimating exposure risks for children
Authors: Elliott Michael R
Published: July 2010

Background

Matched cohort analyses and their extension to conditional logistic and Poisson regression are powerful tools for assessing risk and protective factors in automobile crashes. However, these analyses rely on assumptions about latent (unobserved) ‘crash severity’ risk measures for subjects in the vehicle being common for all such subjects if confounding with crash severity is present. The assumptions may be questionable if adults are being matched to children.

Methods

Simulations were conducted to evaluate conditional Poisson regression in settings where different types of subjects may have different underlying baseline summary risk measures in a given crash—for example, adults and children. Situations were considered where baseline summary risk measures and protective factors are confounded with each other and where the adult and child baseline risk measures are either highly correlated or weakly correlated.

Results

When the risk or protective factor is confounded with crash severity, baseline summary risk measures due to crash severity must be perfectly correlated for all subjects in the crash for the factor to be consistently estimated. Relative bias estimates ranged from 5% to 50% depending on the degree of correlation of the risk measure and the number of matched subjects in a crash.

Conclusions

Matched cohort analysis and its regression extensions are useful tools in the injury epidemiology toolkit, but require assumptions about high correlation of baseline summary risk measures among adults and children to accurately account for confounding between risk or protective factors of interest by crash severity. Conservative coverage intervals can preserve correct nominal coverage as long as the adult–child risk factors are highly correlated.
Modelling the population-level impact of tai-chi on falls and fall-related injury among community-dwelling older people
Authors: Day Lesley , Finch Caroline F , Harrison James E , Hoareau Effie , Segal Leonie , Ullah Shahid
Published: July 2010

Objective

To model the population level impact of tai-chi on future rates of falls and fall-related injury in older people as a tool for policy development.

Design

An epidemiological and economic model for estimating population-level effectiveness of tai-chi.

Setting

Australia, 2009.

Patients or subjects

Australian community-dwelling population aged 70+ years, ambulatory and without debilitating conditions or profound visual defects.

Intervention

Group-based tai-chi, for 1 h twice weekly for 26 weeks, assuming no sustained effect beyond the intervention period.

Main outcome measure

Total falls and fall-related hospitalisation prevented in 2009.

Results

Population-wide tai-chi delivery would prevent an estimated 5440 falls and 109 fall-related hospitalisations, resulting in a 0.18% reduction in the fall-related hospital admission rate for community-dwelling older people. The gross costs per fall and per fall-related hospital admission prevented were $A4414 (€3013) and $A220 712 (€150 684), respectively. A total investment of $A24.01 million (€16.39 million), equivalent to 4.2% of the cost of fall-related episodes of hospital care in 2003/4, would be required to provide tai-chi for 31 998 people and achieve this effect.

Conclusions

Substantial investment in, and high population uptake of, tai-chi would be required to have a large effect on falls and fall-related hospitalisation rates. Although not accounted for in this study, investment in tai-chi is likely to be associated with additional significant health benefits beyond falls prevention. This approach could be applied to other interventions to assist selection of the most cost-effective falls-prevention portfolio for Australia and other countries.
Diagnostic significance of CK19, RET, galectin-3 and HBME-1 expression for papillary thyroid carcinoma
Authors: Zhu Xiaoli , Sun Tuanqi , Lu Hongfen , Zhou Xiaoyan , Lu Yongming , Cai Xu , Zhu Xiongzeng
Published: July 2010

Aims

To evaluate CK19, RET, galectin-3 and HBME-1 expression in papillary thyroid carcinoma (PTC) and to evaluate their diagnostic significance.

Methods

155 PTC specimens and 83 other diseased-thyroid specimens were collected. Immunohistochemistry for CK19, RET, galectin-3 and HBME-1 was performed.

Results

The 155 PTC cases were classified into eight variants according to the WHO classification, including 74 cases of classic PTC, 40 cases of papillary microcarcinoma, and rare variants. CK19, RET, galectin-3 and HBME-1 expression was 87.1% (135/155), 71.0% (110/155), 91.6% (142/155), and 95.5% (148/155), respectively, for the PTC group; expression of all these markers was much higher than that in the control group (p<0.05). However, the expression of these markers did not differ among the variants (p>0.05). The expression of these markers, particularly CK19 and RET, was diffuse and strong in the papillary structure of PTC, but weak and focal in the papilla of tissue with benign disease. The expression of CK19 in follicular PTC was significantly higher than in follicular thyroid carcinoma (FTC) (p<0.05).

Conclusions

CK19, RET, galectin-3 and HBME-1 expression in PTC was higher than that in benign disease cases, but these were not specific markers for PTC. In summary, combining markers can increase the reliability and differential diagnosis of PTC. It is also worth noting that CK19 was very useful not only for the differentiation of benign and malignant papillary structure but also for the differential diagnosis of follicular PTC and FTC.
Accessory nerve palsies
Authors: Wills Adrian J , Sawle Guy V
Published: July 2010

Accessory nerve palsies may cause considerable functional disability and they unfortunately continue to occur as a complication of surgery in and, around the posterior triangle of the neck. Here the causes of accessory nerve palsies are reviewed and the symptoms and signs arising as a consequence are summarised. In addition, the various treatments and their indications are highlighted and discussed.
Do CSF biomarkers help clinicians predict the progression of mild cognitive impairment to dementia?
Authors: Mitchell Alex J , Monge-Argilés J A , Sánchez-Paya J
Published: July 2010

There is increasing interest in the value of CSF biomarkers to predict those individuals with mild cognitive impairment who will progress to dementia. However, lumbar puncture is not routine in these patients and biomarker assays are not universally available. To change clinical practice there must be very good evidence that biomarkers are helpful over and above clinical impression. Here we discuss the merits of CSF biomarkers compared with clinicians using simple bedside cognitive tests. Although every biomarker has a superior positive predictive value, most have inferior negative predictive values. When predicting the progression of mild cognitive impairment, the overall misclassification rate by clinicians using bedside cognitive tests is approximately 38% but this could be reduced to approximately 30% by using Aβ1–42 and to 24% with phosphorylated tau or total tau (or a combination of CSF biomarkers). Clinicians and patients together should decide whether this is sufficient to warrant the additional burden of a lumbar puncture, and the cost of the test, or whether further studies are needed before useful and clinically practical conclusions can be reached.
Comparative salinity tolerance of two legumes, Vigna luteola and Vigna vexillata, from the coast of Trinidad
Authors: Okusanya O. T. , Oyesiku O.
Published: July 2010

The germination and growth responses of two legumes, Vigna luteola and Vigna vexillata, to different salinity levels were compared in laboratory experiments. Vigna luteola seeds tolerated a higher level of salinity and germinated significantly better at high salinities than corresponding results for V. vexillata. Seedlings of V. luteola exhibited a significant increase in dry weight at 10% sea water followed by a significant decrease at 30% seawater and above. Vigna vexillata seedlings showed a gradual decrease in dry weight with increased salinity. Except at 0% seawater, dry weights of V. luteola seedlings were significantly higher than those of V. vexillata at all salinities tested. The proportion of root weight to total plant dry weight increased with increased salinity in V. luteola; the reverse was the case in V. vexillata. In both species, increased salinity resulted in increased sodium content but decreased potassium and calcium contents. While the sodium content of the shoot of V. vexillata was higher than that of V. luteola, the amount in the roots of V. luteola was higher. The potassium and calcium contents were higher in V. luteola than in V. vexillata and the sodium to potassium ratio values were lower in V. luteola than in V. vexillata. The results are compared with those of other legumes and discussed in relation to the habitats of the species, the characteristics of halophytes, and the uses which these legumes may have in salt-enriched lands. Key words: salinity, tolerance, germination, growth, Vigna.
Phytosociology and gradient analysis of a subalpine treed fen in Rocky Mountain National Park, Colorado
Authors: Johnson J. Bradley
Published: July 2010

The vegetation of a subalpine fen in Colorado was studied. Insight was sought into the community structure and factors influencing species distribution of a vegetation type heretofore undescribed in the southern Rocky Mountains. A vegetational gradient was evaluated using detrended correspondence analysis (DCA). Four types of vegetation were subjectively defined; these same types were distinguished by the DCA. DCA further revealed marked differences in the vegetation occurring on peat hummocks versus in hollows. Species composition was related to environment using canonical correspondence analysis (CCA). Water-table depth, hummock height, shading, groundwater temperature, and conductivity were significantly correlated with species distribution, accounting for 51% of the total species variance. Univariate regression was used to examine how tree density varied with environment. The above factors, except for shading and conductivity, were also significantly correlated with tree density. It is suggested that the peat hummocks that form on this moderate fen provide an environment similar to that of an ombrotrophic bog and that these "miniature bogs" form in areas unable to support expansive bogs. Further, these hummocks provide small-scale environmental heterogeneity that exerts a strong control over species composition that would not be evident in studies based on samples of a large areal extent. Keywords: Colorado, gradient analysis, ordination, heterogeneity, peatlands, phytosociology.
Prefertilization events in ovules of Pseudotsuga: ovular secretion and its influence on pollen tubes
Authors: Takaso T. , Aderkas P. von , Owens J. N.
Published: July 2010

A natural ovular secretion from the megagametophyte, essential to sexual reproduction, was examined in Pseudotsuga. This secretion began soon after egg formation or about 1 week before fertilization. Secreted fluid filled the micropylar canal. Morphological study showed that the fluid affected (i) dissolution of intine materials; (ii) pollen distortion that may relate to prezygotic selection; and, (iii) induction of pollen tubes. The origin of the secreted fluid is interpreted from an experiment using homogenates. Elongated pollen supplied with a homogenate of the megagametophyte shows immediate movement of starch grains and body cell. Some pollen formed pollen tubes. Homogenates of the nucellus or the integument elicited little or no response. If ovules are dissected before the natural secretion and kept in high relative humidity, the micropylar canal becomes filled with fluid. This fluid is an artifact resulting from dissection, but is also capable of inducing pollen tubes. Keywords: megagametophyte, ovule, pollen tube, Pseudotsuga, secretion.
Aliphatic components of the epicuticular wax of developing saskatoon (Amelanchier alnifolia) fruit
Authors: Knowles Lisa O. , Knowles N. Richard , Tewari Jalpa P.
Published: July 2010

The epicuticular wax of saskatoon fruit (Amelanchier alnifolia Nutt. cv. Smoky) was analyzed at four stages of maturity. Total wax per unit surface area varied during fruit development, with a net decline from the youngest to the most ripe stage. Surface wax ultrastructure, as revealed by scanning electron microscopy, consisted of pinhead-like crystals that decreased with maturity and platelike crystals that increased with maturity. The major aliphatic compounds were alkanes (C23to C29), long chain esters (C36to C42), primary alcohols (C20to C30), and a secondary alcohol (C29). The esters were composed of primary alcohols (C20to C28) and saturated fatty acids (C16to C24). The most abundant wax components at all stages were nonacosan-10-ol and nonacosane. Keywords: serviceberry, saskatoon fruit, epicuticular wax, aliphatic chemistry, ultrastructure.
Spatial distribution and seed mass variation ofStrophostyles helvolaalong Lake Erie
Authors: Yanful Mary , Maun M. A.
Published: July 2010

Field studies were conducted to determine the survival, seed-mass variability, and reproductive strategies of wild bean, Strophostyles helvola (L.) Ell., plants on the foredunes at Port Burwell Provincial Park along Lake Erie. In spring, a large number of seedlings were found on the drift-line (area of beach where detritis deposits are cast on shore by the waves) and a small number both on the lakeward (mid-beach) and landward (high-beach) ends of the drift-line. Plants growing on the mid-beach were larger and produced a significantly greater number of heavier seeds than those on the drift-line. However, during late fall and winter months, a large proportion of these seeds were moved by wind and wave action to the drift-line. Intraspecific competition was not a limiting factor on the mid-beach; however, on the drift-line, the number of seeds per plant decreased significantly with an increase in density of plants from about 1 to 140/m2, suggesting that intraspecific competition may be an important limiting factor in seed production per plant. The mean mass per seed significantly declined over the growing season of S. helvola. There was a significant increase in mean seed mass with increasing pod size. Seeds in the centre of a pod were significantly heavier than those at the proximal and distal ends of a pod. Strophostyles helvola is able to flourish in the constantly shifting shoreline beach habitats along Lake Erie owing to two main factors. First, it is able to fully utilize the highly variable beach microhabitats and maintain high total reproductive output per square metre. Second, since burial in sand is a major recurrent event on sandy beaches, the high variability in seed mass will be of adaptive significance because seedlings from large seeds will not only be able to emerge from greater depths of burial in sand but also will have greater probability of survival under burial conditions. Keywords: seed mass, plant location, Strophostyles helvola, seed position, spatial distribution.
Sporogenesis, gametogenesis, and progamic phase in Alstroemeria
Authors: Jeu Marjo J. De , Calderé Francesc Garriga , Went Jacques L. Van
Published: July 2010

The sexual reproduction biology of Alstroemeria was studied histologically. The processes of sporogenesis and gametogenesis were described in relation to the development of the male and female organs. Comparative developmental stages in Alstroemeria take much longer than they do in tobacco. Alstroemeria has the monosporic Polygonum type of embryo sac development. Bicellular pollen is formed, which after germination on the receptive stigma immediately undergoes the mitotic division of the generative cell, thus finalizing gametogenesis. Part of the progamic phase has been studied as well. As early as 12 h after pollination, some pollen tubes enter the micropyle of the ovules. This knowledge is important for the application of post-fertilization ovule culture to rescue abortive embryos during interspecific hybridization. Keywords: Alstroemeria, Alstroemeria, Inca Lily, sporogenesis, gametogenesis, progamic phase.
The correlation between iron sulfide precipitation and hypolimnetic phosphorus accumulation during one summer in a softwater lake
Authors: Murray Thomas E.
Published: July 2010

During late summer, 1992, the water immediately overlying the sediment in the anoxic hypolimnion of Crystal Lake, Conn., was saturated with ferrous sulfide (FeS). The average solubility product (pKsp) at the bottom of the hypolimnion was 3.25, which is consistent with other lake and laboratory studies and is in the range of both amorphous FeS and mackinawite. The precipitation of iron sulfide removed Fe2+ and HS− from the water column, and acid volatile sulfide (AVS) accumulated in the top 6–8 cm of the sediment. Pyrite was formed at deeper depths and did not increase during the study. The accumulation of AVS in the sediment was correlated with an increased accumulation of phosphorus in the water column. The rate of accumulation of phosphorus in the hypolimnion was greatest when iron was lost to the sediment as AVS. The statistically significant link between iron storage in the sediment and phosphorus accumulation in the overlying water suggests that reoxidation of ferrous iron to ferric (hydr)oxides is decreased, and therefore precipitation of ferric phosphate is limited.
Cannibalism and trophic structure in a high Arctic lake: insights from stable-isotope analysis
Authors: Hobson Keith A. , Welch Harold E.
Published: July 2010

Stable-nitrogen (15N/14N) isotope ratios (from 2.1‰ in moss to 14.5‰ in Arctic char, Salvelinus alpinus), showed enrichment with trophic level in the food web of Char Lake, Northwest Territories, and may be used to infer trophic position. The average 15N enrichment of 1.5‰ between moss or algae and invertebrates suggests input to the food web of isotopically lighter nitrogen than that measured for these sources of primary production. Stable-carbon (13C/12C) isotope ratios differed between moss and algae by almost 10‰ and indicate that carbon in the Char Lake food web is derived from a blend of these sources of primary production. Arctic char δ15N values for muscle tissue were positively correlated with fork length and clustered into three distinct groups: small fish (1–3 cm, mean δ15N = 5.7‰), which possibly consumed more benthic particles than previously assumed; intermediate-size fish (10–35 cm, mean δ15N = 10‰), which likely depended on larval char as well as their primary zooplankton and chironomid prey; and larger Arctic char, which showed a mean stepwise increase in δ15N of 3.7‰. This suggests that complete cannibalism in this population generally occurs abruptly and is exercised by a relatively small number of large individuals.
A length-based population model and stock–recruitment relationships for red king crab, Paralithodes camtschaticus, in Bristol Bay, Alaska
Authors: Zheng J. , Murphy M. C. , Kruse G. H.
Published: July 2010

A length-based population model was constructed for Bristol Bay red king crab, Paralithodes camtschaticus, incorporating stochastic growth, gradual recruitment over length, and a bowl-shaped pattern for instantaneous natural mortality as a function of length. A nonlinear least squares approach was used to estimate abundance, recruitment, and natural mortality. The model was applied to abundance and catch data from 1968 to 1993. The observed population abundances fit well with the model. Natural mortality was estimated to be three to six times higher in the early 1980s than during other periods. High natural mortality coupled with high harvest rates and followed by low spawning biomass may have contributed to the collapse of the population in the early 1980s and its continued lack of recovery. The stock–recruitment data estimated from the length-based model provided a good fit to both general and autocorrelated Ricker models. The general Ricker model is supported by strong recruitment associated with intermediate levels of spawning biomass and extremely low recruitment related to low spawning stock; the autocorrelated Ricker model fit the data slightly better and is supported by the fact that extremely strong and weak recruitment occurred successively over two separate periods.
Statistical analysis of catch-at-age data with correlated errors
Authors: Myers Ransom A. , Cadigan Noel G.
Published: July 2010

We extend the statistical model used to estimate abundance from commercial catch-at-age data for many of the major commercial fish species in the world. The model we consider combines commercial catch-at-age data and research survey estimates of fish abundance; we extend the model to allow correlated errors among ages within a year for the survey estimates of fish abundance. We also formulate a method for modeling the fishing mortality on the oldest ages of the fish caught. Estimates are obtained using maximum likelihood. We conclude that the level of correlation among ages is sufficiently large to produce large biases in the standard methods for some stocks. The statistical model that includes correlated errors greatly reduces bias and increases efficiency if the correlation in the estimation error is large.
A comparison of electron transport system activity in stream and beaver pond sediments
Authors: Songster-Alpin M. S. , Klotz R. L.
Published: July 2010

Electron transport system (ETS) activity of sediments as an indication of microbial metabolic activity was measured at four beaver pond sites in central New York State. ETS activity, an indication of microbial biomass and respiration, was measured as the reduction of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) to INT-formazan. Since INT can be reduced by both aerobes and anaerobes, the total microbial respiratory activity in the sediments was measured. The ETS activity increased from means of 11.1–65.0 μg O2∙g−1 dry weight∙h−1 at the free-flowing upstream reaches to means of 221.2–262.6 μg O2∙g−1 dry weight∙h−1 within the beaver ponds. ETS activity decreased with increased depth of sediment probably because of the loss of aerobic activity. When ETS activity was expressed on a per unit area basis (grams O2 per square metre per hour), the increase from upstream reaches to the ponds ranged from 13- to 35-fold. This difference increased to 460- to 2180-fold when the activity was expressed per unit length of stream (micrograms O2 per metre per hour). These data showed that beaver ponds greatly increased microbial activity along streams, likely resulting in changes in biogeochemical cycles controlled directly or indirectly by microorganisms.
Effect of supplemental light intensity on white spruce, Engelmann spruce, and mountain hemlock seedlings grown under an extended photoperiod
Authors: Arnott J. T. , Macey D. E.
Published: July 2010

Piceaglauca (Moench) Voss, Piceaengelmannii Parry and Tsugamertensiana (Bong.) Carr. were grown in an unheated "shelterhouse" container nursery, with a high pressure sodium vapour lamp providing a 19-h photoperiod and light intensities of 1600, 800, 400, 200, and 100 lx. The control seedlings received natural daylight and photoperiod. None of the light intensities effectively prevented terminal bud formation in the first two species while no terminal buds were formed at the 1600 lx level in the third one. Higher light intensities delayed the bud forming process in the first and third species, produced significant differences in the number of stem units of the first two, and resulted in larger mean stem unit lengths of the last two species. The longest seedling shoots of all three species were grown under light intensities of 800, 100, and 400 lx, respectively. There were no significant differences in seedling shoot weight, root weight, and root collar diameter among the five light intensity levels used to extend the photoperiod in the first growing season. Light intensity had little effect on 2-year shoot growth of all three species.
Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative process in Douglas-fir. I. Effects on flowering
Authors: Ross S. D. , Webber J. E. , Pharis R. P. , Owens J. N.
Published: July 2010

In two seed orchard trials, profuse female flowering was induced in young, but ontogenetieally mature grafts of inherently poor-flowering clones (1979) and in 9-year-old seedling-origin trees of both good- and poor-flowering families (1981) of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) by the cultural treatment of root-pruning in conjunction with stem injections of the gibberellin A4 and A7 (GA4/7) mixture. Promotion of male flowering, however, was confined to the more sexually mature grafts. As an individual treatment in the 1981 study, root-pruning was more effective than GA4/7, particularly for the poor-flowering families which did not respond well to GA4/7 alone. The two treatments combined had a highly synergistic effect on both male and female flowering, the synergism being relatively greater for the poor-flowering than for the good-flowering families. Although GA4/7 was not tested alone on grafted propagules, its use with root-pruning enhanced an already significant increase in seed- and pollen-cone buds from root-pruning alone by 540 and 92%, respectively. These and subsequent trials have shown root-pruning +GA4/7 to be a most effective cone-bud enhancement treatment for use in young Douglas-fir breeding and seed production orchards.
Interaction between gibberellin A4/7 and root-pruning on the reproductive and vegetative process in Douglas-fir. II. Effects on shoot elongation and its relationship to flowering
Authors: Webber J. E. , Ross S. D. , Pharis R. P. , Owens J. N.
Published: July 2010

Shoot elongation and female flowering response were assessed for gibberellin A4/7 (GA4/7) and root-pruning (RP) treatments in 9- and 10-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings of families with good- and poor-flowering histories. In families with a poor-flowering history, stem injections of GA4/7 significantly enhanced elongation of third-whorl terminal shoots but produced no flowering response. In families with a good-flowering history, GA4/7 treatment had no effect on shoot elongation but did result in a significant increase in seed-cone buds. In contrast, root-pruning significantly retarded shoot growth in families with both good- and poor-flowering histories and was also the single most effective treatment for enhancing flowering. Combined, GA4/7 plus RP had a synergistic effect on flowering and GA4/7 partially overcame the inhibition of shoot growth caused by RP alone. These results are consistent with a hypothesis that exogenous and endogenous gibberellins are used preferentially for vegetative growth processes, with increased flowering occurring only after a threshold concentration of effector gibberellins is reached.
Shoot characteristics of stagnant and vigorous lodgepole pines, and their growth after reciprocal grafting
Authors: Worrall J. , Draper D. A. , Anderson S. A.
Published: July 2010

Differences between shoots of normal and stagnant 20-year-old lodgepole pine were assessed in an attempt to elucidate possible causes of stagnated growth. Leaves of the stagnant plants are relatively short, narrow and few, and the intemodes between fascicles are short. At least on the site studied, foliar mineral concentration was the same for the two types of plant. Long shoot apical meristems are relatively small in height and diameter. The possibility that the differences reside in the apical meristem, i.e., are epigenetic rather than directly environmentally induced, was tested. Reciprocal grafts of vigorous and stagnant scions onto the two types of rootstock showed, however, that growth assumed that typical of the rootstock by the third growing season, and this was maintained in the subsequent season. This result, and the strong resemblance of stagnant shoots to those resulting from transplant shock, suggest that differences in the form and activity of the root systems is a potential cause of stagnation in lodgepole pine.
Stomatal and photosynthetic response of sweet gum (Liquidambarstyraciflua) to flooding
Authors: Pezeshki S. R. , Chambers J. L.
Published: July 2010

Effects of short-term flooding on stomatal conductance, net photosynthesis, and water status of sweet gum (Liquidambarstyraciflua L.) seedlings were studied under controlled environment conditions. Flooding for 9 days induced partial stomatal closure, resulting in significant declines in transpiration and net photosynthesis. The response to flooding was rapid with an average daily stomatal conductance declining from a preflood level of 0.43 cm•s−1 to 0.26 cm•s−1 by 24 h after flooding began (40% reduction). The average preflooding daily net photosynthesis was reduced from 13.7 to 10.2 mg CO2•dm−2•h−1 (25% reduction) during the same period and the average daily stomatal conductance and net photosynthesis for the 9th day of flooding were reduced by 70 and 77%, respectively, compared with preflood levels. The leaf xylem pressure potential measurements, however, indicated that water deficits did not develop as a result of flooding. Partial stomatal reopening 3 days after termination of flooding was noted with an average daily stomatal conductance approaching 63% of the preflood levels and an average daily net photosynthesis reaching 46% of its preflood levels. Maintenance of positive net photosynthesis throughout flooding, and partial stomatal and photosynthetic recovery following drainage may account for the tolerance of sweet gum seedlings to short-term flooding.
Genetic variation and productivity of Populustrichocarpa and its hybrids. I. Morphology and phenology of 50 native clones
Authors: Weber J. C. , Stettler R. F. , Heilman P. E.
Published: July 2010

Morphological and phenological variation among five black cottonwood (Populustrichocarpa Torr. & Gray) clones from each of 10 natural populations were studied at one plantation site in western Washington. Source populations are located in major river valleys, west of the Cascade Mountains, between central Oregon (latitude 44°44′ N) and southern British Columbia (latitude 49°05′ N). Populations and individual clones were selected for superior form and growth rate. Tested at a spacing of 1.2 × 1.2 m, the 50 clones displayed a large range of variation in 15 leaf, branch, and phenology characters studied. Clones and populations differed significantly in 14 and 10 characters, respectively. Population means for seven characters and a character association (principal component) varied clinally with source latitude, longitude, and (or) elevation. The most consistent genetic cline follows a geographic gradient from southwest to northeast: southwestern clones develop smaller leaves on more erect branches, and continue growth later in the fall. Variation patterns seem to reflect regional climatic gradients, annual disturbance in riparian environments, and the life history characteristics of the species. The results point to the great potential of clonal selection for black cottonwood improvement.