bluuebunny/crossref_metadata_2025 huggingface dataset:
A complex system of small RNAs in the unicellular green alga Chlamydomonas reinhardtii
Authors: Zhao Tao , Li Guanglin , Mi Shijun , Li Shan , Hannon Gregory J. , Wang Xiu-Jie , Qi Yijun
Published: May 2007

Endogenous small RNAs function in RNA interference (RNAi) pathways to control gene expression through mRNA cleavage, translational repression, or chromatin modification. Plants and animals contain many microRNAs (miRNAs) that play vital roles in development, including helping to specify cell type and tissue identity. To date, no miRNAs have been reported in unicellular organisms. Here we show that Chlamydomonas reinhardtii, a unicellular green alga, encodes many miRNAs. We also show that a Chlamydomonas miRNA can direct the cleavage of its target mRNA in vivo and in vitro. We further show that the expression of some miRNAs/Candidates increases or decreases during Chlamydomonas gametogenesis. In addition to miRNAs, Chlamydomonas harbors other types of small RNAs including phased small interfering RNAs (siRNAs) that are reminiscent of plant trans-acting siRNAs, as well as siRNAs originating from protein-coding genes and transposons. Our findings suggest that the miRNA pathway and some siRNA pathways are ancient mechanisms of gene regulation that evolved prior to the emergence of multicellularity.
Lin-28 binds IGF-2 mRNA and participates in skeletal myogenesis by increasing translation efficiency
Authors: Polesskaya Anna , Cuvellier Sylvain , Naguibneva Irina , Duquet Arnaud , Moss Eric G. , Harel-Bellan Annick
Published: May 2007

Lin-28 is a highly conserved, RNA-binding, microRNA-regulated protein that is involved in regulation of developmental timing in Caenorhabditis elegans. In mammals, Lin-28 is stage-specifically expressed in embryonic muscle, neurons, and epithelia, as well as in embryonic carcinoma cells, but is suppressed in most adult tissues, with the notable exception of skeletal and cardiac muscle. The specific function and mechanism of action of Lin-28 are not well understood. Here we used loss-of-function and gain-of-function assays in cultured myoblasts to show that expression of Lin-28 is essential for skeletal muscle differentiation in mice. In order to elucidate the specific function of Lin-28, we used a combination of biochemical and functional assays, which revealed that, in differentiating myoblasts, Lin-28 binds to the polysomes and increases the efficiency of protein synthesis. An important target of Lin-28 is IGF-2, a crucial growth and differentiation factor for muscle tissue. Interaction of Lin-28 with translation initiation complexes in skeletal myoblasts and in the embryonic carcinoma cell line P19 was confirmed by localization of Lin-28 to the stress granules, temporary structures that contain stalled mRNA–protein translation complexes. Our results unravel novel mechanisms of translational regulation in skeletal muscle and suggest that Lin-28 performs the role of “translational enhancer” in embryonic and adult cells and tissues.
Tbx3 controls the sinoatrial node gene program and imposes pacemaker function on the atria
Authors: Hoogaars Willem M.H. , Engel Angela , Brons Janynke F. , Verkerk Arie O. , de Lange Frederik J. , Wong L.Y. Elaine , Bakker Martijn L. , Clout Danielle E. , Wakker Vincent , Barnett Phil , Ravesloot Jan Hindrik , Moorman Antoon F.M. , Verheijck E. Etienne , Christoffels Vincent M.
Published: May 2007

The sinoatrial node initiates the heartbeat and controls the rate and rhythm of contraction, thus serving as the pacemaker of the heart. Despite the crucial role of the sinoatrial node in heart function, the mechanisms that underlie its specification and formation are not known. Tbx3, a transcriptional repressor required for development of vertebrates, is expressed in the developing conduction system. Here we show that Tbx3 expression delineates the sinoatrial node region, which runs a gene expression program that is distinct from that of the bordering atrial cells. We found lineage segregation of Tbx3-negative atrial and Tbx3-positive sinoatrial node precursor cells as soon as cardiac cells turn on the atrial gene expression program. Tbx3 deficiency resulted in expansion of expression of the atrial gene program into the sinoatrial node domain, and partial loss of sinoatrial node-specific gene expression. Ectopic expression of Tbx3 in mice revealed that Tbx3 represses the atrial phenotype and imposes the pacemaker phenotype on the atria. The mice displayed arrhythmias and developed functional ectopic pacemakers. These data identify a Tbx3-dependent pathway for the specification and formation of the sinoatrial node, and show that Tbx3 regulates the pacemaker gene expression program and phenotype.
Inducing Ovulation in Xenopus laevis: Figure 1.
Authors: Sive Hazel L. , Grainger Robert M. , Harland Richard M.
Published: May 2007

INTRODUCTION

This protocol describes a method for inducing ovulation in Xenopus laevis for the purpose of in vitro fertilization. Ovulation is induced by injection of human chorionic gonadotropin (hCG) into the dorsal lymph sac of a female frog. Females can lay many hundreds of eggs. However, because the actual number of eggs laid and the efficiency of fertilization are unpredictable, ovulation should be induced in more than one female, even when only a few eggs are required.
Isolating Xenopus laevis Testes: Figure 1.
Authors: Sive Hazel L. , Grainger Robert M. , Harland Richard M.
Published: May 2007

INTRODUCTION

This protocol describes a method of isolating Xenopus laevis testes for use in in vitro fertilization. The testes from one male Xenopus contain sufficient sperm to fertilize several thousand eggs.
Xenopus laevis Egg Collection: Figure 1.
Authors: Sive Hazel L. , Grainger Robert M. , Harland Richard M.
Published: May 2007

INTRODUCTION

This protocol describes procedures for collecting Xenopus laevis eggs from females in which ovulation has been induced.
Mass Spectrometry-Compatible Silver Staining
Authors: Stochaj Wayne R. , Berkelman Tom , Laird Nancy
Published: May 2007

INTRODUCTION

The ammoniacal silver staining method is one of the most sensitive methods used to detect proteins on an SDS-PAGE gel. However, this and other standard silver staining methods are not compatible with mass spectrometry (MS), which is fast becoming the best way to identify proteins isolated on 2D gels. Because the proteins in gels to be analyzed by mass spectroscopy cannot be modified, many of the common sensitizing agents (e.g., glutaraldehyde and strong oxidizing agents) cannot be used. This method is compatible with MALDI and ESI-MS, and it shows an increased ability to deal with semipreparative protein loads without negative staining as compared with other silver staining methods. However, this process is less sensitive than standard silver staining methods.
In Vivo Isotopic Labeling of Proteins for Quantitative Proteomics
Authors: Oda Yoshiya
Published: May 2007

INTRODUCTION

Stable isotope coding strategies are of immense value in determining protein concentration changes in cells and tissues triggered by regulatory stimuli (e.g., drugs and toxins) and disease (e.g., caused by mutational changes). Recognizing and identifying the small number of proteins whose expression levels differ as a consequence of disease or external stimuli are complicated by the complexity of biological extracts and the fact that protein post-translational modifications are numerous and can occur at many sites on a protein. One way of quantifying global protein expression patterns involves in vivo labeling. Using the following protocol, stable isotopes can be incorporated into metabolic products, and the relative difference between these products from cells grown in normal or isotope-enriched media can be readily quantified by MS analysis.
Genetic Manipulation of Mammalian Cells by Microinjection: Figure 1.
Authors: Rose David W.
Published: May 2007

INTRODUCTION

Microinjection allows the introduction of molecules into a defined population of cells at a defined concentration, and the timing of the experiment can be controlled stringently, minimizing problems associated with overexpression. Delivery by microinjection can be used for any type of cell that is adherent in culture, including primary cells. Perhaps its most powerful aspect is the ability to introduce several types of reagents into cells simultaneously, including DNA constructs, a labeled dextran to mark injected cells, antibodies, short interfering RNAs (siRNAs), and peptides. Because siRNA can be generated easily and rapidly for any target gene, it is relatively simple to assess many effects of the knockout of any gene in any type of adherent cell in a matter of days. However, microinjection is not trivial to learn, and requires attention to detail. Also, the limited number of cells involved often does not permit the subsequent analysis of effects on some biochemical parameters. While the major limitation of the approach is the small amount of material obtained, as the sensitivity of analysis techniques increases, so does the usefulness of this method. We emphasize here recent advances in the use of microinjection in combination with siRNA technology.
Embryo Dissection and Micromanipulation Tools: Figure 1.
Authors: Sive Hazel L. , Grainger Robert M. , Harland Richard M.
Published: May 2007

INTRODUCTION

This article describes the creation and maintenance of tools for use in dissection and micromanipulation of embryos. All tools must be kept clean and rinsed with 70% ethanol to keep them sterile.
Housing and Feeding of Xenopus laevis
Authors: Sive Hazel L. , Grainger Robert M. , Harland Richard M.
Published: May 2007

INTRODUCTION

Good animal husbandry is vital for maintaining a healthy frog population. This requires some effort but is generally rewarded by high-quality egg and embryo production. A healthy frog is placid, with moderately slimy skin and a nice pear shape. Jumpy frogs, frogs with dry or excessively slimy skin, bloated frogs, and frogs that look gray and thin or reddish are not healthy and should not be used for egg collection, as this would lead to further deterioration of the animals’ condition, and the resulting eggs would be generally unsuitable for experimental purposes. This article describes proper husbandry techniques for Xenopus laevis in the laboratory.
The importance of unmanaged coastal wetlands to waterbirds at coastal Ghana
Authors: Gbogbo Francis
Published: May 2007

Ghana's 550 km coastline has about 100 wetlands out of which five large ones are managed as Ramsar sites, the rest being unmanaged. Recent pollution and misuse of unmanaged wetlands have necessitated a study into their roles in the support of waterbirds. Waterbird survey on four wetlands between September 2005 and April 2006 revealed that 51 waterbird species make use of the managed compared to 44 in the unmanaged wetlands. Average numbers of waterbirds were higher on the managed wetlands (10,510 ± 4862) than on the unmanaged wetlands (1348 ± 602) (P < 0.05) but mean population density of waterbirds (n/ha) was the same for both the managed (1860 ± 310) and unmanaged (1400 ± 220) (P > 0.05) wetlands. The population densities of waterbirds belonging to guilds 1, 5 and 7 were significantly higher on the managed wetlands (P < 0.05). In contrast, guilds 2 and 4 have significantly higher population densities on the unmanaged wetlands while the population density of guild 3 was the same (P > 0.05). There was an indication that during mid and late periods of the nonbreeding season, the unmanaged wetlands altogether may support a larger number of waterbirds belonging to guilds 2, 3 and 4 than the five managed wetlands.
Abnormal puberty in paediatric Cushing's disease: relationship with adrenal androgen, sex hormone binding globulin and gonadotrophin concentrations
Authors: Dupuis C. C. , Storr H. L. , Perry L. A. , Ho J. T. F. , Ahmed L. , Ong K. K. , Dunger D. B. , Monson J. P. , Grossman A. B. , Besser G. M. , Savage M. O.
Published: May 2007

Objective  Paediatric Cushing's disease is frequently associated with abnormal puberty. We addressed the hypothesis that prepubertal patients show excessive virilization and pubertal patients show suppression of LH and FSH secretion.

Design and measurements  Serum androstenedione (A4), dehydroepiandrosterone sulphate (DHEAS), testosterone (T), and sex hormone binding globulin (SHBG) were determined at diagnosis and converted to standard deviation scores. LH, FSH concentrations were also determined. Severity of CD was assessed from the sleeping midnight cortisol concentration. Puberty was staged and excessive virilization defined as advance in pubic hair stage for breast stage or testicular volume (TV).

Patients  Twenty‐seven CD patients (17 male, 10 female), median age 13·4 years (range 5·9–17·8) were studied.

Results  In the CD group as a whole, A4, DHEAS, T standard deviation scores (SDS) values were normal. SHBG SDS values (n = 19) were low (median –1·93, –4·32–0·86) correlating with BMI (r = –0·49). A4, DHEAS, T, SHBG, LH and FSH did not correlate with midnight cortisol, but A4 and T SDS correlated with ACTH at 09.00 h (both r = 0·51). Thirteen patients (11 male, 2 female) had excessive virilization with increased A4 (P = 0·033), DHEAS (P = 0·008), testosterone (P = 0·033) and decreased SHBG (P = 0·004) compared with subjects without excessive virilization. Pubertal boys (TV ≥ 4 ml) (n = 7) and girls (breasts ≥ stage 2) (n = 8) had low median LH and FSH. Boys had an LH concentration of 1·2 mU/l (0·3–3·5), FSH, 0·9 mU/l (0·2–6·4) and median T SDS, –1·95 (–3·8–4·65), while girls had an LH concentration of 1 mU/l (0·3–7·4).

Conclusions  Many patients had abnormal puberty and excessive virilization associated with increased adrenal androgens and decreased SHBG. Pubertal patients had low LH and FSH suggesting impaired pituitary–gonadal axis function.
The adaptation and relationship of FGF‐23 to changes in mineral metabolism in Graves’ disease
Authors: Park Se Eun , Cho Mi Ae , Kim Se Hwa , Rhee Yumie , Kang Eun Seok , Ahn Chul Woo , Cha Bong Soo , Lee Eun Jig , Kim Kyung Rae , Lee Hyun Chul , Lim Sung‐Kil
Published: May 2007

Objective  The aim of this study was to observe the changes in bone and mineral metabolism and to confirm the regulation of fibroblast growth factor‐23 (FGF‐23) in untreated Graves’ disease.

Patients and measurements  The study comprised 39 patients, with or without Graves’ disease. The Graves’ disease group was made up of 21 newly diagnosed patients, enrolled before starting treatment. Their disease was determined by biochemical and radiological means. The control group was composed of 18 people who were proven to be euthyroid without any diseases affecting bone and mineral metabolism. FGF‐23, calcium, phosphate, PTH, 25‐hydroxyvitamin D [25(OH)D] and 1,25‐dihydroxyvitamin D [1,25(OH)2D] levels and bone turnover markers were compared between these groups.

Results  Serum calcium and phosphate, plasma FGF‐23 and free T4 were significantly higher in the Graves’ disease group than in the healthy control group (P < 0·05). The bone turnover markers serum osteocalcin and C‐terminal cross‐linked telopeptide of type 1 collagen (s‐CTx) were also significantly elevated in the Graves’ disease group, and had a positive correlation with free T4 levels. However, there was no significant decrease in PTH and 1,25(OH)2D in the Graves’ disease group. Plasma levels of FGF‐23 exhibited a positive correlation with serum phosphate levels and with free T4 levels (P < 0·05).

Conclusions  These findings suggest that FGF‐23 is physiologically related to serum phosphate homeostasis, as indicated indirectly by the changes in bone and mineral metabolism, in untreated Graves’ disease.
Reduced maternal corticosteroid‐binding globulin and cortisol levels in pre‐eclampsia and gamete recipient pregnancies
Authors: Ho Jui T. , Lewis John G. , O’Loughlin Peter , Bagley Christopher J. , Romero Roberto , Dekker Gus A. , Torpy David J.
Published: May 2007

Objective  To measure and contrast maternal cortisol and corticosteroid‐binding globulin (CBG) levels in pregnancies with normal outcomes, pre‐eclampsia, intrauterine growth restriction (IUGR) and in gamete recipients.

Study design  Prospective study of 93 women at high risk of pre‐eclampsia, including gamete recipients (n = 22) and 33 controls. Plasma total and free cortisol and CBG were measured every 2 weeks from 16 weeks’ gestation until delivery.

Results  Forty‐two per cent of the high‐risk group had complications, including pre‐eclampsia (n = 11), gestational hypertension (n = 16) and small‐for‐gestational‐age (SGA) neonates (n = 12). There were no complications in the controls. In all groups, plasma CBG concentrations increased progressively across gestation (P < 0·05), in parallel to total cortisol, but fell significantly from 36 weeks’ gestation onwards, with a corresponding rise in free cortisol concentrations. In pre‐eclampsia and gestational hypertension, plasma CBG, and total and free cortisol concentrations were lower from 36 weeks onwards (P < 0·05). In IUGR, plasma CBG concentrations were suppressed from 28 weeks’ gestation until delivery (P < 0·05), but with no significant difference in plasma total and free cortisol. Gamete recipients had significantly lower plasma CBG from 20 weeks’ gestation onwards, and plasma total and free cortisol were reduced at 24 and 32 weeks onwards, respectively.

Conclusions  Maternal plasma CBG, total and free cortisol concentrations are reduced in pre‐eclampsia/gestational hypertension, and markedly reduced in gamete recipients. Low CBG may be due to reduced synthesis or enhanced inflammation‐driven degradation. Low maternal cortisol may be due to a lack of placental corticotropin‐releasing hormone or reduced maternal ACTH, driving cortisol production. Low maternal cortisol may influence the foetal hypothalamic–pituitary–adrenal axis and disease patterns later in life following complicated pregnancy.
Thyroid cysts: a new extra‐adrenal site of aldosterone synthase expression and increased aldosterone content
Authors: Greenman Yona , Trostanetsky Yana , Ben‐Shemen Sarit , Grazas Nili , Limor Rona , Osher Etty , Lewicka Sabina , Vecsei Paul , Stern Naftali
Published: May 2007

Background  The rapid re‐accumulation of fluid following aspiration of thyroid cystic lesions suggests that active transport of sodium and water may be involved in volume regulation of these lesions. In this study we address the possibility that aldosterone may take part in this process.

Subjects and methods  Thirty‐one patients (29 women and two men), with a mean age of 52·7 ± 13·2 years (range: 27–77 years) underwent evaluation for thyroid nodules that had a sonographic cystic component. Cystic fluid obtained by FNA biopsy was sent for cytological examination and biochemical measurements. In 10 patients, material was collected for RNA extraction and determination of aldosterone synthase expression by RT‐PCR amplification.

Results  All lesions were benign, cystic, colloid nodules. Cyst fluid aldosterone levels as measured by routine radioimmunoassay (RIA) were elevated above the normal plasma levels in all but five patients. Mean aldosterone levels were 27·1 ± 22·9 ng/dl (SD) (range: 5·9–117·5 ng/dl). In contrast, cyst cortisol values were in the low, low normal serum range (6·2 ± 2·9 µg/dl, range: 0·2–10·2 µg/dl). Sodium, chloride and potassium levels were 137 ± 4·7 mEq/l, 98 ± 5 mEq/l and 4·9 ± 1·4 mEq/l, respectively. Plasma aldosterone levels were normal in all patients tested. To confirm these results, 12 samples were assayed after extraction and chromatography using a highly specific antibody. Cyst aldosterone levels in this group were elevated above the normal serum range in all but one patient (mean concentration: 24·5 ± 14·6 ng/dl, range: 8·72–40·1 ng/dl). In this group, 18(OH)B levels were within the normal plasma range (12–55 ng/dl) in all but one patient (34·9 ± 17 ng/dl). Furthermore, aldosterone synthase mRNA expression was found in aspirates of four of 10 patients.

Conclusions  The increased aldosterone concentration and the presence of aldosterone synthase expression suggest that aldosterone may be locally produced and secreted in thyroid tissue. The pathophysiological implications of this finding remain to be established.
Genetic analysis of the PAX8 gene in children with congenital hypothyroidism and dysgenetic or eutopic thyroid glands: identification of a novel sequence variant
Authors: Tonacchera Massimo , Banco Maria Elena , Montanelli Lucia , Di Cosmo Caterina , Agretti Patrizia , De Marco Giuseppina , Ferrarini Eleonora , Ordookhani Arash , Perri Anna , Chiovato Luca , Santini Ferruccio , Vitti Paolo , Pinchera Aldo
Published: May 2007

Objective  To analyse the coding region of PAX8 in individuals with congenital (CH) or post neonatal hypothyroidism due to dysgenetic (TD) or eutopic thyroid glands.

Design and patients  Forty‐three children with CH and TD (13 agenesis, 23 ectopia, and seven hypoplasia), one subject with post neonatal onset of hypothyroidism and thyroid ectopia, 15 children with CH and eutopic thyroid glands and six euthyroid adults with thyroid hemiagenesis were enrolled as cases, along with 120 healthy individuals as controls.

Measurements  Exons 2–8 of the PAX8 were directly sequenced. HeLa and HEK293 cells were transfected with PAX8 wild‐type (PAX8‐WT), mutant PAX8, p300, thyroid transcription factor 1 (TTF‐1) and thyroglobulin promoter pGL3 (TG prom‐pGL3). Synergism of TTF‐1 with PAX8‐WT vs. mutant and activity of PAX8‐WT vs. mutant in accompaniment with p300 on TG prom‐pGL3 were also assessed. The luminescence produced by PAX8‐WT and mutant PAX8 was measured.

Results  Among patients and controls only a 15‐year‐old girl with thyroid ectopia showed a heterozygous transition of cytosine to thymine at position 674 in exon 6, which changed a conserved threonine at position 225 to methionine (PAX8‐T225M). Her father and sister harboured PAX8‐T225M without abnormal thyroid phenotypes. PAX8‐T225M and PAX8‐WT similarly increased luciferase activity and had a similar synergistic effect with TTF‐1. At 500 ng p300, however, PAX8‐T225M could not significantly increase TG promoter activity when compared to PAX8‐T225M alone, while PAX8‐WT +500 ng p300 induction was significantly higher than PAX8‐WT alone (P < 0·001). Cotransfection of TTF‐1 together with PAX8‐T225M resulted in rescuing of the lack of synergism with p300.

Conclusions  PAX8 mutations in congenital hypothyroidism due to dysgenetic or orthotopic thyroid glands are rare. PAX8‐T225M is probably a rare variant.
Quantitative measurement of thyroid blood flow for differentiation of painless thyroiditis from Graves’ disease
Authors: Ota Hisashi , Amino Nobuyuki , Morita Shinji , Kobayashi Kaoru , Kubota Sumihisa , Fukata Shuji , Kamiyama Naohisa , Miyauchi Akira
Published: May 2007

Objective  Differentiation between destruction‐induced thyrotoxicosis and Graves’ thyrotoxicosis is important for selection of proper therapy. It is, however, often difficult to make this distinction without measurement of radioactive iodine uptake. We investigated the possibility that assessment of thyroid blood flow would allow differentiation between the two entities.

Patients and measurements  One hundred and fourteen untreated patients with thyrotoxicosis (56 Graves’ disease, 28 painless thyroiditis, 30 subacute thyroiditis) and 25 normal controls were examined. Serum levels of freeT4 (FT4), freeT3 (FT3) and TSH were measured by chemiluminescent immunoassay, and anti‐TSH receptor antibodies (TSH‐binding inhibitory immunoglobulin, TBII) were measured by enzyme‐linked immunosorbent assay. Thyroid volume and blood flow (TBF) were measured quantitatively by ultrasonography.

Results  TBF was significantly higher in Graves’ disease (mean ± 1SD: 14·9 ± 6·4%, P < 0·0001) than in painless thyroiditis (0·8 ± 0·5%), subacute thyroiditis (0·9 ± 0·7%) and in normal controls (0·8 ± 0·5%). All patients with Graves’ disease had TBF values of more than 4% and all patients with painless thyroiditis and subacute thyroiditis had TBF values less than 4%. TBF values significantly correlated with values of radioactive iodine uptake (RAIU) either at 3 h (r = 0·492, P < 0·01) or 24 h (r = 0·762, P < 0·001) within the Graves’ disease and painless thyroiditis groups. There was no relationship between TBF values and thyroid volumes or values of TBII in the Graves’ disease group. All patients with Graves’ disease had positive TBII of 15% or more. Three of 28 patients with painless thyroiditis and one of 30 patients with subacute thyroiditis had positive TBII.

Conclusion  TBF was quantitatively measured by power Doppler ultrasonography and was more effective than TBII for differentiation between destruction‐induced thyrotoxicosis (painless or subacute thyroiditis) and Graves’ thyrotoxicosis. TBF values of less than 4% in untreated thyrotoxic patients are laboratory signals of destruction‐induced thyrotoxicosis and if these are determined, the radioactive iodine uptake test can be omitted for differential diagnosis of these two types of thyrotoxicosis.
Lack of electrocardiographic changes in women with polycystic ovary syndrome
Authors: Orio Francesco , Palomba Stefano , Cascella Teresa , Manguso Francesco , Vuolo Laura , Tafuri Domenico , Vigorito Carlo , Lombardi Gaetano , Liguori Vincenzo , Colao Annamaria , Giallauria Francesco
Published: May 2007

Objective  The aim of the present study was to investigate the potential alterations in electrocardiographic (ECG) pattern in patients with polycystic ovary syndrome (PCOS).

Patients  Fifty PCOS patients and 50 age‐ and body mass index‐matched healthy women were studied.

Methods  We assessed hormonal and metabolic pattern, and performed ECG analysis for evaluating PQ interval, QRS duration, minimum and maximum QT interval corrected for heart rate (QTcmin and QTcmax, respectively), corrected QT dispersion (QTcd), corrected J point/T‐wave interval (JTendc), corrected JTmax interval (JTmaxc), and corrected Tmax‐end interval (Tmax‐endc).

Results  QTcmin (399 ± 21 vs. 396 ± 25 ms, P = 0·51); QTc max (445 ± 25 vs. 443 ± 27 ms, P = 0·70); and QTcd (46 ± 13 vs. 47 ± 15 ms, P = 0·72); JTendc (337 ± 14 vs. 336 ± 16 ms1/2, P = 0·74); and JTmaxc (256 ± 22 vs. 258 ± 21 ms1/2, P = 0·64); Tmax‐endc (81 ± 18 vs. 78 ± 19 ms1/2, P = 0·42) were not significantly different between PCOS and healthy women.

Conclusion  Despite profound differences in hormonal and metabolic pattern, our data demonstrate no significant difference in ECG pattern in PCOS compared to healthy controls.
An early age‐related increase in the frequency of CD4+ Foxp3+ cells in BDC2·5NOD mice
Authors: Thomas David C. , Mellanby Richard J. , Phillips Jenny M. , Cooke Anne
Published: May 2007

Summary The role of regulatory T cells (Treg) in maintaining tolerance to self has been intensively scrutinized, particularly since the discovery of Foxp3 as a Treg‐specific transcription factor. The BDC2·5NOD transgenic mouse is an excellent model of immunoregulation because it has a very low incidence of diabetes despite a highly autoreactive T‐cell repertoire. It has previously been shown that reactivity against islets decreases with age in BDC2·5NOD mice. Here we show that there is a markedly higher frequency of Foxp3+ Treg in the CD4+ subset of 16–20‐week‐old mice compared with 4‐ or 8‐week‐old mice. This phenomenon can be observed in the spleen, thymus, pancreatic draining lymph nodes and the pancreas itself. We show that this early age‐related increase in the frequency of Foxp3+ cells does not occur in wild‐type NOD, BALB/c or C57BL/6 mice. Further, we show that, in contrast to some reports on Treg in wild‐type NOD mice, the suppressive function of BDC2·5NOD Treg from 16‐ to 20‐week‐old mice is intact and comparable to that from 4‐ to 8‐week‐old mice both in vitro and in vivo. Our data offer insights into the long‐term protection of BDC2·5NOD mice from diabetes and an explanation for the age‐related decrease in anti‐islet responses seen in BDC2·5NOD mice.
Variation in reproductive success within a subtropical fig/pollinator mutualism
Authors: Bronstein Judith L. , Hossaert‐McKey Martine
Published: May 2007

Abstract. Plants pollinated by specialists are often thought to receive exceptionally high‐quality pollinator service, but in relatively low and unpredictable quantities. We examine and reject this hypothesis for an obligate mutualism between a subtropical New World fig (Ficus aurea) and its species‐specific pollinator (Pegoscapus jimenezi). Fig wasps lay eggs within the flowers they pollinate; their offspring destroy a large proportion of fig's seeds. In a 6‐year study of this interaction in Florida, U.S.A., we found that pollination intensity was in fact relatively high. Also contrary to expectations, reproductive success of both mutualists (as well as other wasps cohabiting the figs) was extremely variable and generally low, at three different scales of sampling: among figs from a single crop of one tree (thirty‐four figs), among crops produced at different times by that tree (126 figs), and across trees over a 1‐year period (379 figs). Although variable, fig contents were not completely unpredictable. For example, seed and wasp numbers increased with the number of flowers in a fig, and female and male flower numbers increased together. Little is yet known about the causes either of these relationships or of the massive fig‐to‐fig variation itself, although there is some evidence that they exist in other fig species as well. Further investigations of these patterns should shed new light on the ecology and evolution of this mutualism.
Effects of within‐tree flowering asynchrony on the dynamics of seed and wasp production in an Australian fig species
Authors: Cook James M. , Power Sally A.
Published: May 2007

Abstract.Within‐tree flowering asynchrony in figs, which may allow pollinating wasps to avoid the risks of dispersal in inclement conditions, has been predicted as a trait to be favoured in highly seasonal environments. Comparisons of such asynchronous figs with better‐known species that exhibit within‐tree synchrony might also be expected to reveal differences in the outcome of the conflict between pollinator wasp and fig seed production, and the dynamics of non‐pollinating wasps. This paper presents data on wasp and seed production inFicus rubiginosaDesf. ex Vent., an asynchronous species that occurs in the highly seasonal environment of south‐eastern Australia. In contrast to recent studies of figs showing within‐tree flowering synchrony, syconium size was the main determinant of wasp and seed production inF. rubiginosa. Non‐pollinating wasps were highly prevalent but occurred in low numbers and appeared to have relatively little impact on pollinator wasp or fig seed production. Data on flower positions revealed that non‐pollinating wasps occurred almost exclusively in the outer layer of flowers, while pollinators were more abundant in the inner flower layer, which may represent an area of enemy‐free space. The ratio of seeds to female pollinator wasps, an index of fig sex allocation, was more seed‐biased than in several New World fig species that exhibit within‐tree synchrony. This last result supports the idea that within‐tree fruiting asynchrony permits a degree of self‐pollination inF. rubiginosa.
Exceptions to the one:one relationship between African fig trees and their fig wasp pollinators: possible evolutionary scenarios
Authors: Michaloud G. , Carrière S. , Kobbi M.
Published: May 2007

Abstract. The mutualistic breeding system involving fig trees (Moraceae, Ficus) and fig wasps (Hymenoptera, Chalcidoidea, Agaoninae) would appear so specialized that one may wonder at the evolutionary processes that could be responsible for the existence of about 750 species‐specific associations. In this paper we present data concerning two cases of species specificity breakdown between African fig trees and fig wasps. We then analyse the possible evolutionary scenarios which could be responsible, as well as the possible evolutionary outcomes of the observed situations. Our analyses range in scale from continental to habitats, and fig crops to individual figs (syconia). Habitat shifts and ecological barriers seem to be the more likely explanations for the evolution of novel fig tree‐fig wasp associations, but sympatric and parapatric scenarios cannot be ruled out.
Molecular phylogenies of figs and their pollinator wasps
Authors: Herre Edward Allen , Machado C. A. , Bermingham E. , Nason J. D. , Windsor D. M. , McCafferty S. S. , Houten W. Van , Bachmann K.
Published: May 2007

Abstract. We collected and analysed nucleotide sequence and protein electrophoretic data in order to estimate phylogenies of figs and fig‐pollinating wasps at several taxonomic scales. The relatively conserved chloroplast gene coding rbCl allowed the estimation of the taxonomic position of Ficus relative to other genera within the Moraceae. Further, in conjunction with chloroplast tRNA spacer genes, rbcL sequences allowed the partial resolution of the phylogenetic associations of fig species from different parts of the world with representatives from all the recognized subgenera of Ficus. The phylogeny of the corresponding wasp species that pollinate most of those taxa was estimated using mitochondrial COI‐COII and 12S ribosomal genes. At a fine scale, the phylogenies of species within two subgenera of figs growing in Panama (Urostigma, and Pharmacosycea) were estimated by using protein electrophoretic data. The phylogeny of the corresponding pollinator wasp species was estimated using COII sequence data. Although we need to extend the taxa sampled and augment the molecular database, the host and pollinator phylogenies show a high degree of congruence and the results support the predominance of strict‐sense co‐evolution between figs and their pollinator wasps at both global and fine scales.
Seed dispersal in an African fig tree: birds as high quantity, low quality dispersers?
Authors: Compton S. G. , Craig A. J. F. K. , Waters I. W. R.
Published: May 2007

Abstract. Ficus burtt‐davyi is a shrub or small tree found in the south and east of South Africa. Based on studies carried out in an area where the plant grows mainly as a rock‐splitter, we first describe the nature and timing of the fruit resources it offers to potential dispersal agents, and then the animals that feed on the fruits. The figs are eaten by a diverse avian disperser assemblage, although just two species comprised about half of the recorded visits to the trees. Germination trials with seeds defecated by the birds found that they germinated more quickly than control seeds. Small terrestrial mammals and ants were also found to have a role in fig seed dispersal which may be disproportionate to the number of seeds they transport.
ITE Merlewood Land Classification of Great Britain
Authors: Bunce R. G. H. , Barr C. J. , Clarke R. T. , Howard D. C. , Lane A. M. J.
Published: May 2007

Abstract. The Institute of Terrestrial Ecology (ITE) has classified the 1 km squares in Great Britain (GB) into thirty‐two environmental strata, termed land classes, as a basis for ecological survey. The classes have been used in biogeographical studies of the distribution of individual species and species assemblages. The concept behind the technique is that there is an association between the environmental character of land and ecological parameters. The initial classification was based on a sample of squares drawn from a regular grid. The data for the 12121 km squares classified were drawn from published maps; the number of squares was limited by the available computing power. Subsequently the availability of more powerful computers and the need to improve geographical definition have led to the allocation of every 1 km square to its appropriate class. This paper has been written to summarise the principles involved in the development of the system and indicate the range of projects for which it has been used. The extension of the classification from a sample to the complete coverage of GB revealed the importance of the structure and style of data used to produce the classification. The significance of these conclusions for future work is discussed, with particular reference to automated methods of data capture.
A biogeographical analysis of terrestrial isopods (Isopoda, Oniscidea) from the central Aegean islands (Greece)
Authors: Sfenthourakis Spyros
Published: May 2007

Abstract. Terrestrial isopods (Isopoda, Oniscidea) of forty‐three central Aegean islands and islets are analysed from a biogeographical point of view. The oniscid fauna consists of sixty‐nine species, thirty‐two genera and fourteen families and is characterized by Aegean elements that have an eastern Mediterranean origin. Endemism is at the level of 20%, similar to that of oniscids from other Mediterranean archipelagoes. Analysis of species distribution through both idiographic and quantitative approaches (faunal similarity among islands using Jaccard's index, simple matching indices and the UPGMA clustering technique) resulted in the recognition of a major disjunction between Kykladesplus‐Ikaria and eastern islands‐plus‐Astypalea and four noteworthy island groups: the eastern islands, Naxos‐Ikaria, Amorgos, and all other Kyklades. Island similarities are generally consistent with the known palaeogeography of the area with the exception of Ikaria's placement with Naxos among the Kyklades. Also, the ‘eastern’ character of Astypalea is in conflict with evidence from other known taxa.
Species turnover on a protected subtropical barrier island: a long‐term study
Authors: Herwitz Stanley R. , Wunderlin Richard P. , Hansen Bruce P.
Published: May 2007

Abstract. The commercial development that threatens the biodiversity of coastal habitats is particularly severe along the sandy shores of subtropical Florida. The objective of our study was to test the applicability of the equilibrium theory of island biogeography to Cayo‐Costa Island, the largest protected barrier island remaining in peninsular Florida. Our null hypothesis was that there would be no change in the number and composition of native vascular plant species on Cayo‐Costa 15 years after the first inventory of the island's flora. Our reinventory documents a total of 230 native species in 1990–92 compared to 255 native species in 1975–77. Immigrants were represented by twenty‐eight new species, while extinctions totalled fifty‐three species. These results indicate a turnover rate of approximately 2.7 species yr‐1 with an extinction rate of 3.5 species yr‐1 and an immigration rate of 1.9 species yr‐1. The net loss of 1.6 species yr‐1 suggests a non‐equilibrium condition that is not readily explained by changes in habitat diversity associated with the documented patterns of shoreline erosion and deposition. Cayo‐Costa's net loss of twenty‐five native species (including one tree species and four shrub species) was localized mainly in those habitats where there had been a significant increase in the relative abundance of the naturalized weedy exotic species Schinus terebinthifolius and Casuarina equisetifolia. We conclude that the spread of naturalized weedy species limits the applicability of the equilibrium theory of island biogeography to species‐rich subtropical barrier islands, even in cases where the islands are protected from human disturbance.
Evidence of a Holocene and continuing recent expansion of lowland rain forest in humid, tropical North Queensland
Authors: Hopkins M. S. , Head J. , Ash J. E. , Hewett R. K. , Graham A. W.
Published: May 2007

Abstract. The identification and radiocarbon dating of charcoal collected under tropical rain forest indicated that sclerophyll forests dominated by Eucalyptus occupied parts of the wet tropical lowlands in the Daintree region of North Queensland at least intermittently from 12,000 yr bp until very recently. The results extend the late Pleistocene expansion of pyrophytic, sclerophyll forests which occurred in the upland rain forests to a humid, megathermic coastal lowlands region. Unlike the early Holocene re‐expansion of rain forests which occurred generally on the uplands, the sclerophyll forests in the lowland study area were present until at least 1400 yr bp. Changes in coastal geomorphology and coastline positions during the late Quaternary were examined in the study area by superimposing sea levels derived from published curves on sea‐bed contours. The results indicate that a very rapid decrease in the extent of the coastal plain occurred during the late Pleistocene. Between 12,000 and 9000 yr bp, 26 km of the coastal plain was submerged and this would have inevitably resulted in concentrations of Aboriginal populations in the area of the present coastline. It is suggested that burning activities by Aborigines in the coastal lowlands were sufficient to reestablish sclerophyll forests during the latter part of the Holocene from approximately 4000 yr bp following a wanner and wetter period which would have been conducive to rain forest re‐expansion. Although the evidence suggests that the most recent rain forest recolonization occurred in the study area more than 1000 years ago, the process is still continuing elsewhere in the wet tropical lowlands in North Queensland. The process of eucalypt forest replacement by rain forest may have accelerated since the arrival of Europeans and the concomitant decrease in Aboriginal management.
Variation in the composition and structure of tropical savannas as a function of rainfall and soil texture along a large‐scale climatic gradient in the Northern Territory, Australia
Authors: Williams R. J. , Duff G. A. , Bowman D. M. J. S. , Cook G. D.
Published: May 2007

Abstract. Variation in structural and compositional attributes of tropical savannas are described in relation to variation in annual rainfall and soil texture along a subcontinental‐scale gradient of rainfall in the wet‐dry tropics of the Northern Territory, Australia. Rainfall varies along the gradient from over 1500 mm p.a. in the Darwin region (c. 12° S) to less than 500 mm in the Tennant Creek region (c. 18° S). Soils are patchy, and sands, loams and clays may occur in all major districts within the region. We utilized a large data set (1657 quadrats ° 291 woody species; with numerous measured and derived sample variables) covering an area of 0.5 million km2. Correlations between floristic composition of woody species and environmental variables were assessed using DCA ordination and vector fitting of environmental variables. Vectors of annual rainfall and soil texture were highly correlated with variation in species composition. Multiple regression analyses incorporating linear and quadratic components of mean annual rainfall and topsoil clay content were performed on three structural attributes (tree height, tree cover, tree basal area) and two compositional attributes (woody species richness, deciduous tree species richness). Tree height declined with decreasing rainfall; cover, basal area, woody species richness and deciduous species richness all declined with decreasing rainfall and increasing soil clay content. Regression models accounted for between 17% and 45% of the variation in the data sets. Variation in other factors such as soil depth, landscape position and recent land‐use practices (for which there were no data on an individual quadrat basis) are likely to have contributed to the large residual variation in the data set.
The shrubs of the Western Ghats (South India): floristics and status
Authors: Krishnan Rani M. , Davidar Priya
Published: May 2007

Abstract. This study examines the understorey shrub community in a wet evergreen forest of South India. The shrub community in the evergreen forests of the Western Ghats, Eastern Ghats, Sri Lanka, South‐east Asia, Neotropics, Africa and Madagascar are compared. The shrub community is richer in the Old World Tropics as compared to the Neotropics. The common families in the Old World Tropics are: Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae and Annonaceae. The number of families constituting the understorey shrub community falls from forty‐six (Western Ghats) to thirteen (Central Amazon). The study concludes that the evergreen forests in the Western Ghats probably have the richest understorey shrub community.

Résumé. L'étude concerne la communauté d'arbustes de sous‐bois d'une forêt sempervirente du Sud de l'lnde. Les communautés d'arbustes dans les forèts sempervirentes des Ghâts Occidentaux, des Ghâts Orientaux, du Sri Lanka, du Sud‐Est Asie, des Néotropiques, de l'Afrique et de Madagascar sont comparées. La communauté d'arbustes est plus riche dans le Vieux Monde Tropical que dans les Néotropiques. Les families communes dans le Vieux Monde Tropical sont; Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae et Annonaceae. Le nombre de families constituant la communauté d'arbustes de sous‐bois varie de 46 (Ghâts Occidentaux) à 13 (Amazonie Centrale). L'étude conclue que les forêts sempervierentes des Ghàts Occidentaux ont probablement la plus riche communauté d'arbustes de sois‐bois.

Mots clés. Communauté d'arbustes de sous‐bois, forêts sempervirentes, Ghâts Occidentaux, endémisme, Inde.
The vegetational history of the northern Apennines, Italy: information from three new sequences and a review of Regional vegetational change
Authors: Watson Clare S.
Published: May 2007

Abstract. The results of pollen analysis and radiocarbon dating are presented from three northern Apennine sequences; Lago Padule in northern Tuscany and Lago Pratignano and Ospitale in the Emilia‐Romagnan Apennines. This is the first detailed pollen stratigraphic information from sites in Emilia‐Romagna and north Tuscany and extends eastwards the area from which information on vegetational history is available.

The sequence from Lago Padule is one of the most complete Holocene records known from the northern Apennine region. Lago Pratignano has the deepest sequence of organic sediments (1544 cm) and the fastest rates of sediment accumulation (up to 28 cm per 100 years) providing the highest resolution record for the mid to late Holocene periods in the region. High rates of sedimentation have also occurred at Ospitale where organic sediments are 780 cm deep and began to form at approximately 5500 bp.

The record from Lago Padule is compared with Holocene records from two nearby sites and a series of Regional Pollen Assemblage Zones is defined for the eastern area of the northern Apennines. The main features of vegetational change identified are: (i) a‘pioneer’phase of rapid forest development during the early Holocene followed by the establishment of an upper forest belt dominated by Abies, and a belt of mixed deciduous forest at lower altitudes; (ii) the appearance and rapid expansion of Fagus between approximately 5200 bp and 2900 bp forming a mixed Abies‐Fagus association in the upper forest belt; and (iii) the overall reduction of forest cover, and dominance of Fagus in the arboreal vegetation from around 2900 bp.

The scheme of Regional PAZs for the eastern area is used as a framework for the review of pollen stratigraphic information and radiocarbon dates from other sites in the northern Apennine region. Characteristics of pollen records which can be identified in sequences from across the region are identified and the chronology of similar changes in pollen stratigraphy is examined. The scheme of four regional PAZs for the Holocene period is shown to be valid for the entire northern Apennine region. The examination of a series of pollen records shows that Fagus appeared earlier in the western than the eastern part of the region during the mid Holocene and became dominant in the northern Apennine forests post 3000 bp. The impact of anthropogenic activity and climatic change on the spread and development of Fagus are discussed. The palynological evidence which is now available from the northern Apennines is compared with information for the region shown in the‘European pollen maps’of Huntley & Birks (1983). This study provides an updated review of the representation of different tree taxa in Holocene pollen records from the northern Apennines and illustrates the role of the northern Apennines as a refugium for trees during the Wurmian Lateglacial.
Book review
Authors: HASLAM S.M.
Published: May 2007

Book Reviewed in this articel:

Cushing, C. E., Cummins, K.W. and Minshall, G.W. (eds) (1995) Ecosystems of the World 22. River and stream ecosystems.