bluuebunny/crossref_metadata_2025 huggingface dataset:
LONG‐TERM CRIME DESISTANCE AND RECIDIVISM PATTERNS—EVIDENCE FROM THE ESSEX COUNTY CONVICTED FELON STUDY*
Authors: KURLYCHEK MEGAN C. , BUSHWAY SHAWN D. , BRAME ROBERT
Published: February 2012

Two conflicting definitions of desistance exist in the criminology literature. The first definition is instantaneous desistance in which an offender simply chooses to end a criminal career instantaneously moving to a zero rate of offending (Blumstein et al., 1986). The second definition views desistance as a process by which the offending rate declines steadily over time to zero or to a point close to zero (Bushway et al., 2001; Laub and Sampson, 2001; Leblanc and Loeber, 1998). In this article, we capitalize on the underlying assumptions of several parametric survival distributions to gain a better understanding of which of these models best describes actual patterns of desistance. All models are examined using 18 years of follow‐up data on a cohort of felony convicts in Essex County, NJ. Our analysis leads us to three conclusions. First, some people have already desisted at the beginning of the follow‐up period, which is consistent with the notion of “instantaneous desistance.” Second, a three‐parameter model that allows for a turning point in the risk of recidivism followed by a long period of decline fits the data best. This conclusion suggests that for those offenders active at the start of the study period, the risk of recidivism is declining over time. However, we also find that a simpler two‐group model fits the data almost as well and gains superiority in the later years of follow‐up. This last point is particularly relevant as it suggests that the observed gradual decline in the hazard over time is a result of a compositional effect rather than of a pattern of individually declining hazards.
Early postmenopausal bone loss and what to do about it
Authors: Recker Robert R.
Published: February 2012

The pattern of lifelong changes in bone mass in women characterized in several publications generally shows that peak adult bone mass is achieved at about the end of adolescence or later, and begins to decline as menopause approaches. Uncertainties remain regarding the exact age at which peak bone mass is reached and when it starts to decline. The data indicate that the onset of rapid bone loss in healthy women begins at about two years before the last menses and is complete at about four to five years after the last menses. The bone loss at the spine, total body, and femoral neck over these years is equal to about one T‐score and is largely irreversible after it occurs. This presentation examines the data on these questions and focuses on the perimenopausal pattern of rapid bone loss and the implications for identifying and managing the later‐life risk of fracture.
Vitamin D: an essential component for skeletal health
Authors: Wimalawansa Sunil J.
Published: February 2012

Vitamin D deficiency is increasing worldwide. Ultraviolet rays are supposed to provide humans over 80% of our vitamin D requirement; the rest is received through diet and supplements. In addition to enhancing calcium absorption from the intestine and mineralization of the osteoid tissue, vitamin D has many other physiological effects, including neuromodulation, improving muscle strength and coordination, insulin release, immunity and prevention of infections, and curtailing cancer. Whether the increased incidence of vitamin D deficiency is related to increased incidences of nonskeletal disorders remains to be determined. Serum levels of 25‐hydroxyvitamin [25(OH)D] above 30 ng/mL indicate vitamin D sufficiency. An additional 1,000 IU of vitamin D/day is sufficient for most lighter‐skinned individuals, whereas an extra 2,000 IU/day is needed by the elderly and dark‐skinned individuals to maintain normal 25(OH)D levels. Additional research is needed to clarify the relationship between vitamin D and the nonskeletal systems, nonclassic functions, and targets of vitamin D.
Production of the Endangered Rio Grande Silvery Minnow, Hybognathus amarus, in the Conservation Rearing Facility at the Los Lunas Silvery Minnow Refugium
Authors: Hutson Alison M. , Toya Louie A. , Tave Douglas
Published: February 2012

This article describes the initial season‐long yield trial of raising the endangered Rio Grande silvery minnow, Hybognathus amarus, in the conservation rearing facility at the Los Lunas Silvery Minnow Refugium. Ten thousand fish (90,900/ha) were stocked on June 22, 2010. Production was based on a total of 653 mL (5.936 L/ha) of 11‐37‐0 N‐P‐K and 5.5 kg (50 kg/ha) of alfalfa pellets. Fish were harvested in October; almost all were harvested 18–27 October. At stocking, fish averaged 21.7 mm total length and mean weight was 0.10 g. At harvest, fish averaged 48.98 mm and 1.12 g. Fish were sampled monthly, and increased lengths and weights through the study were significant (P = 0.05). Five thousand eight hundred ninety‐two fish were harvested (58.92% survival). Yield was 59.99 kg/ha. Temperature, dissolved oxygen (DO), pH, un‐ionized ammonia, nitrite, turbidity, alkalinity, and chloride were measured at seven sites throughout the outdoor refugium. Secchi disc visibility was measured in the stream and in the ponds. Only two variables (DO and pH) went outside permitted values, but were easily corrected. Harvest was difficult due to the many different naturalized areas consisting of varying depths, channel widths, and substrates.
Impact of Aeration on the Growth Performance of Silver Barb, Puntius gonionotus, during Fingerling Rearing
Authors: Das Pratap Chandra , Jena Joykrushna , Mishra Bibhudatta , Pati Bikash Kumar
Published: February 2012

Impact of aeration on growth of silver barb, Puntius gonionotus during fingerling rearing was studied through a 100‐d rearing experiment conducted in 18 concrete tanks of 50 m2 (10 × 5 × 1.2 m) size. Fry (0.74 ± 0.27 g, 35 ± 6 mm) were stocked in the experimental tanks at three stocking densities (25, 50, and 75 fry/m2) and were evaluated with and without provision of 6 h (2400–0600 h) of night time aeration. Aeration resulted in higher pH and dissolved oxygen regime and increased fingerling length and weight. The results suggest a rearing density of 75/m2 to be ideal for rearing fry to fingerling of this species when aeration is provided, whereas, under non‐aerated condition, rearing the fry to fingerling stage at 50/m2 was found advantageous over those at 25 and 75/m2.
Effects of KK‐42 on Expression of 3‐Hydroxy‐3‐Methylglutaryl‐Coenzyme A Reductase in Penaeus schmitti
Authors: Xia Xichao , Wang Wenfeng , Wang Xueshen , Li Xin , Ning Qianji
Published: February 2012

Methyl farnesoate (MF) is an important hormone controlling crustacean growth. Our previous study has demonstrated that the treatment of juvenile hormone antagonist KK‐42 can accelerate growth of Penaeus schmitti. The expression of 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGR), a key enzyme of MF precursor production, was assayed using real‐time PCR, and hemolymph MF titer was determined by high‐performance liquid chromatography. Shrimp, 3.5–5.0 cm long, were soaked for 1 min in KK‐42 solution at a concentration of 1.95 × 10−4 mol/L or in the solution without KK‐42 and then cultured in normal way. Results showed that the highest level of hmgr transcript occurred in mandibular organ (MO). Administration of KK‐42 resulted in HMGR expression to be notably depressed in the MO, even reduced by 80.2% (P < 0.01) and 90.7% (P < 0.01) on Day 1 and Day 7, respectively. The MF level showed a decline trend in KK‐42 treatment compared to that of corresponding control group. Our present study demonstrates that treatment of KK‐42 significantly inhibits HMGR expression in different tissues especially in the MO, which is likely one of KK‐42 growth‐promoting mechanisms on P. schmitti.
Introduction: The View from 1710
Authors: KNIGHTS MARK
Published: February 2012

The articles in this volume, planned to mark the tercentenary of the impeachment of Dr Henry Sacheverell on 23 March 1710, reassess the importance of his trial. Sacheverell's attack on the revolution of 1688, and the principles which underpinned it, allows us to question how far, 20 years later, a whig revolution had prevailed. The articles suggest that the revolution continued to be contested; that in 1710 the high church tory vision temporarily triumphed; that the flood of print showed the importance of religious dispute in shaping the public sphere; that the debate over Sacheverell connected Westminster and the public, not just in England but also in Ireland; that there was an important disagreement between high and low church about how to respond to the press's licentiousness, part of a story about the shift away from prepublication censorship towards regulation of print and copyright; that the print controversy over the trial was vituperative, ‘impolite’ and traded lies and misrepresentations; that Sacheverell's critics sought to associate him with harlots in a bid to suggest that his strong influence over women was unhealthy; that Sacheverell, on the other hand, deliberately depicted himself as a martyr; and that, for all its religious heat, 1710 was also important for an early enlightenment debate about political economy, since the tory vision on Church and state also embraced a reoriented foreign policy and that this contest over imperial visions had important consequences for the development of the colonies after 1714.
A Non‐Resisting, Passively Obedient Revolution: Lord North and Grey and the Tory Response to the Sacheverell Impeachment*
Authors: SZECHI DANIEL
Published: February 2012

This article is a notes and comments‐style edition of two documents written by William North, Baron North and Grey, during the Sacheverell impeachment. The first of these was a response to arguments made by the Commons' managers before the Lords, the second was North and Grey's notes for his own speech in defence of Sacheverell. It is argued that together these encapsulate a strong tory's view of the impeachment and the revolution of 1688. Given the subsequently jacobite trajectory of North and Grey's career, it is suggested that these documents also offer an insight into the tory mentalité at the point when the first tory party was on the eve of its greatest political and electoral triumphs and before it turned against the Hanoverian dynasty.
Irish Tories and Victims of Whig Persecution: Sacheverell Fever by Proxy*
Authors: HAYTON D.W.
Published: February 2012

Although the trial of Dr Sacheverell attracted considerable public attention in Ireland, and a great deal of the pamphlet literature generated in England was reprinted in Dublin, there is little explicit evidence of the invocation of Sacheverell's name by Irish tories, in parliament, at elections, or in the indigenous press culture. On the surface, this seems hard to explain, even though Irish protestants were naturally more sensitive than their English counterparts to any challenge to the legitimacy of ‘Revolution principles’, for at the same time the protestant Irish ‘political nation’ was bitterly divided by a conflict of parties on the English model, and, indeed, regarded their own struggles as an extension of the warfare of whigs and tories in England. This article seeks to account for the non‐appearance of Dr Sacheverell in Irish political discourse by emphasizing the presence in Ireland of two surrogates: Francis Higgins, the roaring anglican controversialist who, like Sacheverell himself, courted ‘persecution’ by bishops and whig governments, and Sir Constantine Phipps, lord chancellor of Ireland 1710–14, who turned himself into a tory champion in Ireland by using some of Sacheverell's methods of self‐promotion. The fact that both were closely associated with the Doctor – Higgins as a chosen replacement for Sacheverell in the pulpit in 1710, Phipps as a defence counsel at the impeachment – infused both with reflected glamour and enabled Irish tories to express their support for Sacheverell indirectly, without calling into question their loyalty to the Williamite settlement.
Sacheverell's Harlots: Non‐Resistance on Paper and in Practice
Authors: NICHOLSON EIRWEN E.C.
Published: February 2012

This article's point of entry is Plate 3 of William Hogarth's print sequence The Harlot's Progress (1732), specifically Hogarth's deliberate, hostile choice of an unframed, titled, small portrait engraving of the Reverend Dr Henry Sacheverell as a ‘pin‐up’ within the harlot's bedroom furniture. The article reappraises and recontextualises Hogarth's choice of Sacheverell, which makes sense in the context of Hogarth's life and work, but which, with Hogarthian irony, is further informed by the subsequent discovery (1747) of Sacheverell's internment alongside a notorious prostitute, given the association of Sacheverell's celebrity and notoriety with his alleged support from London's ‘kind shees’ and streetwalkers at the time of his trial. This, together with a strong, nascent material consumerist culture, sees Sacheverell anticipating the ‘politics out of doors’ associated with John Wilkes by 50 years and is a specifically gendered version that has gone largely unexplored.
Silver as an Example of the Applications of Photochemistry to the Synthesis and Uses of Nanomaterials†,‡
Authors: Stamplecoskie Kevin G. , Scaiano Juan C.
Published: February 2012

Photochemistry is a powerful tool for controlled synthesis of metal nanoparticles, their modification and in many of the applications that these materials have. Plasmon transitions offer a unique way of delivering energy with exquisite spatial and temporal control and can be used to advantage where visible wavelength control is required. This account of research at the University of Ottawa summarizes details of the synthesis, modification and applications of silver nanostructures.
Can a Sector‐Wide Approach Underpin and Advance Universal Health Coverage?
Authors: Ulikpan Anar , Hill Peter , Malik Asmat Ullah , Shakarishvili George , Narula Indermohan
Published: February 2012

Fragmented management approach makes the provision of comprehensive health care for achieving universal health coverage very unlikely. This article aims to explore the potential contribution of a systemic approach—the sector‐wide approach (SWAp)—to achieving universal health coverage (UHC), using the Mongolian context as an example. The paper describes UHC and factors that hinder its achievement in developing countries, based on the Mongolian experience. The analysis focuses on the root factors hindering the achievement of UHC and examines how these affect system and local capacity critical for achieving UHC. Two principally different approaches, a sector‐wide (holistic) approach and a standalone project (fragmented) approach are compared in terms of their contribution to the main indicators of achieving UHC. The current stage of the Mongolian health SWAp is identified and early rewards of a SWAp are presented. The paper proposes a SWAp as a potential approach to tackle these root factors to help in achieving UHC, because it is a promising instrument that promotes a systems‐strengthening and capacity‐building approach to enable effective coordination of standalone projects in alignment with the national priorities.
Application of probability distributions to the modeling of biogenic CO2 fluxes in life cycle assessment
Authors: Cherubini Francesco , Guest Geoffrey , Strømman Anders H.
Published: February 2012

In life cycle assessment (LCA), the same characterization factors are conventionally applied irrespective of when the emissions occur (the same importance is given to emissions in the past, present, and future). When the assessment is constrained by fixed timeframes, the appropriateness of this paradigm is questioned and the temporal distribution of emissions becomes of relevance. One typical example is the accounting for biogenic CO2 emissions and removals. This article proposes a methodology for assessing the climate impact of time‐distributed CO2 fluxes using probability distributions. Three selected wood applications, such as fuel, nonstructural panels, and housing construction materials are assessed. In all the cases, CO2 sequestration in growing trees is modeled with an appropriate forest growth function, whereas CO2 emissions from wood oxidation are modeled with different probability distributions, such as the delta function, the uniform distribution, the exponential distribution, and the chi‐square distribution. The combination of these CO2 fluxes with the global carbon cycle provides the respective changes caused in CO2 atmospheric concentration and hence in the radiative forcing. The latter is then used as basis for climate impact metrics. Results demonstrate the utility of using emission and removal functions rather than single pulses, which generally overestimate the climate impact of CO2 emissions, especially in presence of short time horizons. Characterization factors for biogenic CO2 are provided for selected combinations of biomass species, rotation periods, and probability distributions. The time discrepancy between biogenic CO2 emissions and capture through regrowth results in a certain climate impact, even for a system that is carbon neutral over time. For the oxidation rate of wooden products, the use of a chi‐square distribution appears the most reliable and appropriate option under a methodological perspective. The feasibility of its adoption in LCA and emission accounting from harvested wood products deserves further scientific considerations.
Yield potential of Miscanthus energy crops in the Loess Plateau of China
Authors: Liu Wei , Yan Juan , Li Jianqiang , Sang Tao
Published: February 2012

Growing second‐generation energy crops on marginal land is conceptualized as one of the primary means of future bioenergy development. However, the extent to which marginal land can support energy crop production remains unclear. The Loess Plateau of China, one of the most seriously eroded regions of the world, is particularly rich in marginal land. On the basis of the previous field experiment of planting Miscanthus species in Qingyang of the Gansu Province, herein, we estimated the yield potential of Miscanthus lutarioriparius, the species with the highest biomass, across the Loess Plateau. On the basis of the radiation model previously developed from Miscanthus field trials, annual precipitation was introduced as an additional variable for yield estimate in the semiarid and semihumid regions of the Loess Plateau. Of 62 million hectares (Mha) of the Loess Plateau, our model estimated that 48.7 Mha can potentially support Miscanthus growth, with the average yield of 17.8 t ha−1 yr−1. After excluding high‐quality cropland and pasture and land suitable for afforestation, a total of 33.3 Mha of presumably marginal land were left available for producing the energy crop at the average yield of 16.8 t ha−1 yr−1 and the total annual yield of 0.56 billion tons. The analysis of environmental factors indicated that erosion, aridity, and field steepness were the primary contributors to the poor quality of the marginal land. The change of land uses from traditional agriculture to energy crop production may prevent further erosion and land degradation and consequently establish a sustainable economy for the region.
Double labelling of neural grafts for identification of sites mediating growth in snails
Authors: Gomot A.
Published: February 2012

Several parameters were studied in an experiment on intracerebral neural grafts in young snails (Helix aspersa aspersa) in which growth was blocked by removal of the mesocerebrum. The results demonstrate that transplantation of adult mesocerebrum neurons from another subspecies (H aspersa maxima) into the location of the ablated mesocerebrum in the brain of a young juvenile host, leads to functional recovery. In addition, double labelling with charcoal for topographical localisation and fast blue for observation of survival and integration of fluorescent cells within the host brain demonstrated the tolerance to the grafted cells and the successful growth of the chimeric brain. The surviving neurons were mainly located in the median region of the reconstituted brain near the islets of metacerebrum neurons. It is possible that some trophic factors promote growth in the host brain and development of the grafted cells. However, resumption of growth requires the presence of the neurosecretory cells particular to the mesocerebrum which secrete growth hormone. The fast‐blue dye, which is still detectable after several months, is useful to track single cells for the study of the functional capacities of the different populations of neurons in the cerebral ganglia and for exploring neuronal replacement strategies in the damaged brain.
Further similarities between astrocytes and perisinusoidal stellate cells of liver (Ito cells): Colocalization of desmin and glial fibrillary acidic protein in astroglial primary cultures
Authors: Buniatian Gayane Hrachia
Published: February 2012

The colocalization of desmin and glial fibrillary acidic protein (GFAP) in astrocytes was inferred from previous studies demonstrating a unique antigenic composition comprising GFAP, desmin and vimentin in perisinusoidal stellate cells (PSC) of liver which share several features with astrocytes. In the present study the colocalization of GFAP and desmin was investigated by double‐immunolabeling experiments in 12‐day‐old rat astroglial primary cultures with antiserum against GFAP and two commercial monoclonal antibodies against desmin, antibodies of clone DEU‐10 and clone DEB‐5. These antibodies selectively decorated the perisinusoidal stellate cells (PSC) of liver for which desmin is known to be a marker. The results obtained with astroglial cells demonstrate that both GFAP and desmin are coexpressed in morphologically different types, process‐bearing and process‐lacking astrocytes. The expression of desmin was apparently more pronounced in process‐lacking astrocytes and was considerably lower in process‐bearing ones. In process‐lacking astrocytes, in contrast to filamentous cytoplasmic staining for GFAP, the immunoreactivity for desmin was non‐filamentous and was irregularly spread in the perinuclear cytoplasm of the cells, while in process‐bearing astrocytes the pattern of staining for desmin was similar to that of GFAP. The variability in the intensity and pattern of staining for desmin in astrocytes might be due to transitional stages of differentiation for part of the cells. This interpretation was supported by the presence of GFAP in the cells weakly expressing smooth muscle alpha‐actin and the absence of GFAP in the cells enriched with microfilaments.
Imaging of subcellular structures by scanning ion microscopy and mass spectrometry. Advantage of cryofixation and freeze substitution procedure over chemical preparation
Authors: Mony Marie‐Ce´cile , Larras‐Regard Eliane
Published: February 2012

With the IMS 4F, a scanning ion microscope and mass spectrometer (SIMS), it is possible to map chemical elements with a lateral resolution of about 250 nm over a field of view of 50 × 50 μm2. Such conditions should enable the imaging of subcellular structures with constitutive ionic species such as CN−, P−, S−. The study was performed on heart and renal tissues prepared either by chemical procedure or cryofixation‐freeze substitution (CF‐FS) prior to embedding. Heart tissue was chosen because cardiocytes display a simple structural organization whereas the structural organization of kidney tubular cells is more complex. Whatever the preparation procedure, nuclei were easily identified due to their high P− content. The CN−, P−, and S− ion images obtained on heart and renal tissues prepared by chemical procedure showed weak contrasts inside the cytoplasm so that it was difficult to recognize the organelles. After CF‐FS, enhanced contrasted images allow organelle (mitochondria, myofibrils, lysosomes, vacuoles, basal lamina, etc) characterization. This work demonstrated that CF‐FS is a more suitable preparation procedure than chemical method to reveal organelle structures by their chemical composition. The improvements in the imaging of these structures is an essential step to establish the correlation between the localization of a trace element (or a molecule tagged with isotopes or particular atoms) and its subcellular targets.
Impact of taxol‐mediated stabilization of microtubules on nuclear morphology, ploidy levels and cell growth in maize roots
Authors: Balusˇka Frantisˇek , Sˇamaj Jozef , Volkmann Dieter , Barlow Peter W
Published: February 2012

Direct contact of the radiating perinuclear microtubules (MTs) with the nuclear envelope was visualized with an immunogold technique using specific monoclonal tubulin antibody. The possibility that these perinuclear MT arrays are involved in establishing and maintaining nuclear organization during the interphase of cycling cells in maize root meristems was tested using taxol, a MT‐stabilizing agent. Taxol not only stabilized all MTs against the action of the MT‐disrupters colchicine and oryzalin but also prevented these agents from their usual induction of nuclear enlargement and decondensation of nuclear chromatin. On the contrary, nuclear size decreased and the chromatin became more compact in mitotically cycling cells of the taxol‐treated root apices. Moreover, taxol prevented the stimulation, by colchicine and oryzalin, of the onset of the S phase in cells of the quiescent centre and proximal root meristem. Exposure of maize roots to taxol strongly decreased final cell volumes, suggesting that the more condensed nuclear chromatin is less efficient in genome expression and that this accounts for the restriction of cellular growth. All these findings support the hypothesis that MT arrays, radiating from the nuclear surface, are an essential part of an integrated plant ‘cell body’ consisting of nucleus and the MT cytoskeleton, and that they regulate, perhaps via their impact on chromatin condensation and activity, progress through the plant cell cycle.
Primary human muscle satellite cell culture: Variations of cell yield, proliferation and differentiation rates according to age and sex of donors, site of muscle biopsy, and delay before processing
Authors: Bonavaud Sylvie , Thibert Philippe , Gherardi Romain K , Barlovatz‐Meimon Georgia
Published: February 2012

The present study was performed to determine the influence on human satellite cell yield, proliferation, and differentiation rates of: 1) sex and age of donors; 2) site of the muscle biopsy; and 3) delay before processing of the muscle biopsy sample. We used a standardized primary muscle cell culture procedure on 206 normal muscle samples obtained from different muscle groups of patients aged from 20 to 88 years, at time of orthopedic surgery. Sex of donors did not influence muscle culture parameters. In contrast, aging tended to affect muscle cell yield (age group 50–59 years vs 70–79 years, P < 0.08), but not myogenic cell abilities to proliferate and to fuse into myotubes. The anatomic origin of muscle samples used for culture appeared to influence culture parameters. In contrast with other tested muscles, the tensor fasciae muscle gave both a good cell yield (174 ± 25 103 cells per gram) and homogeneous proliferation and differentiation rates. Storage of the muscle sample at 4°C in transport medium was associated with a very high cell yield when processing was done in early hours after biopsy (277 ± 50 103 cells/g), a high and stable cell yield when processing was done from day 1 to day 3 after biopsy (185 ± 15 103 cells/g), and a poor cell yield when processing was done after day 4 (111 ± 13 103 cells/g). Storage of muscle biopsy samples at 4°C for 1 to 4 days was associated with good proliferation and fusion rates. In conclusion, these data validate a convenient procedure of primary human muscle cell culture, using tensor fasciae muscle biopsy, which is easily done at time of orthopedic surgery, obtained from men and women of all ages (if possible less than 70 years to obtain good cell yield), and allowing of 1–3 days of storage before processing that may compensate uncertainty of the exact time of availability of muscle samples for the scientist.
Changes of ribonucleoproteic structures of embryonic epidermal cell nuclei during differentiation and maturation
Authors: Zavala Guadalupe , Vázquez‐Nin Gerardo H
Published: February 2012

The nuclear structure of the epiblast and skin cells was studied during the development of the chick embryo (Gallus domesticus). Ribonucleoproteic structures (RNPs) and chromatin were characterized with preferential staining techniques. The changes of the frequency of a type of RNP particle, the perichromatin granule, from gastrulating embryos to newly hatched chick, were analyzed by electron microscopic quantitative stereology. The changes of nuclear and nucleolar volume were estimated using the light microscope. The differentiation of ectoderm from epiblast is characterized by a significant increase in the nucleolar volume and in the frequency of perichromatin granules. These features suggest that ectoderm differentiation involves a general increment of mRNA and rRNA transcription. At the beginning the synthesis of a sulfhydryl‐rich protein, which is coincident with the thickening of the bilayered epithelium to a multilayered epithelium, a large increase of the numerical density of perichromatin granules not accompanied by any modification of the nucleolar volume was found. The same changes characterize the acquisition of epidermal mature cell features immediately after hatching. These findings as well as previous results concerning the differentiation of central nervous system and striated muscle suggest that the increases of the number of perichromatin granules take place during the acquisition of new cytophysiological states related to functional maturation and not to early stages of cell differentiation.
Adaptive evolution of water homeostasis regulation in amphibians: Vasotocin and hydrins
Authors: Acher R. , Chauvet J. , Rouillé Y.
Published: February 2012

Volemia and osmolality homeostasis is ensured in vertebrates through neuroendocrine reflexes, involving an afferent neural branch from baro‐ and osmo‐receptors to hypothalamus and an efferent endocrine branch from secretory neurons to target hydroosmotic cells equipped with receptors and effectors. Whereas the osmoregulatory system in the tadpole comprises three organs, namely gut, kidney and gills, as in freshwater fishes, the adult displays a quaternary strategy with gut, kidney, urinary bladder and skin. In particular, the cutaneous permeability entails a great evaporative water loss when the animal is in the open air, loss that must be compensated by water reabsorption through the nephron and the urinary bladder and mainly by water uptake through the skin. Adaptation occurred at the level of these organs by regulation of their permeability through neurohypophysial hormones. Aside from vasotocin, active on the three organs, all anuran Amphibia possess hydrin 2 (vasotocinyl‐Gly), a peptide resulting from a down‐regulation of provasotocin processing. Exceptionally Xenopus laevis, a permanent aquatic toad, has hydrin 1 (vasotocinyl‐Gly‐Lys‐Arg) instead of hydrin 2. Hydrins are somewhat more active than vasotocin on water permeation of skin and bladder but are devoid of antidiuretic activity. Adaptive evolution has created, along with the vasotocin‐nephron system, preserved in all terrestrial non‐mammalian tetrapods, additional functions such as the hydrin‐skin and hydrin‐bladder rehydration mechanisms. Specific hydrin receptors might exist in the skin and the bladder, different from those of vasotocin in the kidney. It is assumed that the water channel recruitment mechanism, found for vasopressin acting on the collecting duct principal cells in mammals, is also involved when vasotocin and hydrins stimulate their hydroosmotic target cells and that hormone‐regulated aquaporin 2‐like proteins could be identified in the three osmoregulatory organs of amphibians.
A novel method to determine the diffusional water permeability of oocyte plasma membranes
Authors: Iserovich Pavel , Kuang Kunyan , Chun Terry , Fischbarg Jorge
Published: February 2012

Measurements of the cell membrane diffusional water permeability (Pd) are important to characterize water passage across water channels and across the lipid bilayer component of the membrane. Existing methods for those measurements are involved; however, we report here a simple procedure to estimate Pd in Xenopus laevis oocytes and similar large cells. Due to the different densities of H2O and D2O (heavy water), an oocyte transferred from normal medium to a D2O‐based medium floats initially, but subsequently sinks when a certain amount of the water originally in them is replaced by the D2O that diffuses in. We describe how the ‘flotation time’ (time that oocytes float in a heavy water solution before they start sinking) yields the Pd of the plasma membrane. Determination of Pd by this procedure and by the rate of tritiated water (T2O) efflux give for Pd results which are very close: 2.2 ± 0.2 (n = 8) and 2.0 ± 0.1 (n = 6) μm/s, respectively (T = 10°C). Further‐more, our method detects the increase in Pd elicited in oocytes by either expression of water channel proteins, or by treating them with the pore‐forming antibiotic amphotericin B. This method appears useful to gauge the expression and function of pore‐forming, water‐permeable membrane proteins.
Length of the selectivity filter of aquaporin‐1*
Authors: Whittembury Guillermo , González Ernesto , Gutiérrez Antonio M , Echevarría Miriam , Hernández Celia Sofía
Published: February 2012

We have characterized the selectivity filter of the water channel aquaporin‐1 (AQP1) of proximal straight tubules (PST), as an equivalent cylindrical structure with a diameter of ∼ 4.5 Å, where water molecules single file. We report here efforts to evaluate its length. PST were dissected from rabbit kidneys, held with pipettes in a chamber bathed in a buffered mannitol isosmotic solution (MBS, 295 mOsm/kg). Changes in tubule cell volume with time (dV/Adt), were monitored, on line, with an inverted microscope, a TV camera and an image processor. Osmotic permeability coefficients, Pos, and reflection coefficients (σs) were measured with several solutes: mannitol (M), raffinose (R), sucrose (S), glycerol (G), acetamide (A) and urea (U). For this purpose PST were suddenly exposed (in ∼ 80 ms and for 20 s) to a hyperosmolality step (ΔCs) achieved by adding to MBS a ΔCs of 35 mOsm/kg of either R, S, M, G, A or U. Cells shrunk within 500 ms of t = 0 to their osmometric volume and remained shrunk for the 20 s of the ΔCs. Pos was measured from the shrinking curves; Pos = 3000 ± 25 μm/s with either R, S, M, G, A or U. This procedure also allowed to calculate σs; σs = 1.00 for R, S, M, G, A and U, indicating that these solutes do not penetrate the water channel. In contrast, the shrinking curves produced by a ΔCs = 35 mOsm/kg formamide (F) were 15th to 16th slower and smaller (subosmometric) than those produced by a ΔCs = 35 mOsm/kg of R, S, M, G, A or U. Furthermore, with F, cells did not remain shrunk. They recovered their original volume within 3 s. Pos (measured with F) is denoted as Pos*; Pos* = 480 ± 30 μm/s. σs,formamide (denoted σsp) = 0.16 ± 0.01. Use of σsp and Pos* values in Hill's equations for the bimodal theory of osmosis leads to n = 2–3, n being the number of water molecules single filing within the channel selectivity filter, whose length must lie within 6 to 9 Å, a value lower than previous values calculated from the Pos Pd* ratio.
Rhythmic activities of hypothalamic magnocellular neurons: Autocontrol mechanisms
Authors: Richard Philippe , Moos Françoise , Dayanithi Govindan , Gouzènes Laurent , Sabatier Nancy
Published: February 2012

Electrophysiological recordings in lactating rats show that oxytocin (OT) and vasopressin (AVP) neurons exhibit specific patterns of activities in relation to peripheral stimuli: periodic bursting firing for OT neurons during suckling, phasic firing for AVP neurons during hyperosmolarity (systemic injection of hypertonic saline). These activities are autocontrolled by OT and AVP released somato‐dentritically within the hypothalamic magnocellular nuclei. In vivo, OT enhances the amplitude and frequency of bursts, an effect accompanied with an increase in basal firing rate. However, the characteristics of firing change as facilitation proceeds: the spike patterns become very irregular with clusters of spikes spaced by long silences; the firing rate is highly variable and clearly oscillates before facilitated bursts. This unstable behaviour dramatically decreases during intense tonic activation which temporarily interrupts bursting, and could therefore be a prerequisite for bursting. In vivo, the effects of AVP depend on the initial firing pattern of AVP neurons: AVP excites weakly active neurons (increasing duration of active periods and decreasing silences), inhibits highly active neurons, and does not affect neurons with intermediate phasic activity. AVP brings the entire population of AVP neurons to discharge with a medium phasic activity characterised by periods of firing and silence lasting 20–40 s, a pattern shown to optimise the release of AVP from the neurohypophysis. Each of the peptides (OT or AVP) induces an increase in intracellular Ca2+ concentration, specifically in the neurons containing either OT or AVP respectively. OT evokes the release of Ca2+ from IP3‐sensitive intracellular stores. AVP induces an influx of Ca2+ through voltage‐dependent Ca2+ channels of T‐, L‐ and N‐types. We postulate that the facilitatory autocontrol of OT and AVP neurons could be mediated by Ca2+ known to play a key role in the control of the patterns of phasic neurons.
Calcium‐induced calcium increase in secretory vesicles of permeabilized rat neurohypophysial nerve terminals
Authors: Troadec Jean‐Denis , Thirion Sylvie , Laugier Jean‐Pierre , Nicaise Ghislain
Published: February 2012

Digitonin‐permeabilized isolated neurohypophysial nerve terminals are known to release their secretory vesicle content under calcium challenge. On this preparation, we monitored intra‐organelle Ca2+ concentration using digital fluorescence microscopy of Fura‐2. The superfusion of artificial intracellular solution containing 10 to 50 μM Ca2+ induced an intra‐organelle [Ca2+] increase. Two major organelles are candidates for this increase: secretory vesicles and mitochondria. In an attempt to detect calcium changes in the vesicles, ruthenium red was used to impair mitochondrial calcium uptake. Part of the ruthenium red‐insensitive intra‐organelle [Ca2+] increase was abolished by raising sodium in the solution. Removing sodium boosted the intra‐organelle [Ca2+] increase. These results taken together suggest the participation of Na/Ca exchange, known to exist in the membrane of these secretory vesicles. In addition to Na/Ca exchange, there would be at least another mechanism of vesicular calcium intake, as suggested by the partial inhibition of intra‐organelle [Ca2+] increase obtained under acidic compartments: neutralization with NH4Cl. This mechanism remains to be defined. The main conclusion presented here, that an intravesicular [Ca2+] increase takes place at the rate of secretion, was predicted by the hypothesis that intravesicular Ca2+ changes would be involved in stimulus‐secretion coupling.
Inhibition of nucleolar protein nucleolin by electroporation with anti‐nucleolin antibodies results in an increase of the nucleolar size
Authors: Abadía‐Molina Francisco , Torreblanca José , García‐Herdugo Gregorio , Moreno Francisco J
Published: February 2012

Electroporation of exponentially growing human larynx epidermoid carcinoma cells (HEp‐2) with a serum against nucleolin, one of the most abundant non‐histone nuclear proteins, has shown, 24 h after electroporation, a significant increase in the size of the nucleolus of these cells compared with normal HEp‐2 cells (non‐electroporated) and electroporated HEp‐2 cells in the absence of antinucleolin serum (P < 0.01). Image analysis evaluation of the different nucleolar components proved a major contribution of the dense fibrillar component to the total nucleolar size in cells electroporated with anti‐nucleolin antibodies, more than that corresponding to the dense fibrillar component in cells from any of the control groups (P < 0.01), indicating that the reported increase in nucleolar size was due to a marked enlargement of the dense fibrillar regions. These results, in agreement with previous biochemical and molecular biology studies, suggest a pivotal role for nucleolin in pre‐rRNA processing and constitute morphological evidence supporting this role. Following nucleolin inhibition, impaired pre‐rRNA processing might result in an accumulation of this molecular species in the dense fibrillar component of the nucleolus, where pre‐rRNA is first present.
Active nuclear import of single‐stranded oligonucleotides and their complexes with non‐karyophilic macromolecules
Authors: Hartig Roland , Shoeman Robert L , Janetzko Alfred , Grüb Sabine , Traub Peter
Published: February 2012

The objective of this investigation was to characterize intranuclear accumulation of oligonucleotides and their adducts with non‐karyophilic compounds in cultured animal cells and thus to present a model system for nucleic acid‐mediated nuclear import. In digitonin‐permeabilized cells, nuclear uptake of 3′‐FITC‐labeled, single‐stranded 25‐mer oligodeoxyribonucleotides was independent of added cytosolic protein, largely energy‐dependent, inhibitable by wheat germ agglutinin but not by N‐ethylmaleimide, and a function of their base composition. When coupled to FITC‐labeled streptavidin or streptavidin‐bovine serum albumin conjugates, the oligonucleotides delivered the proteins to the nuclear interior with rates roughly proportional to their karyophilicity as free molecules. Transport activity was also demonstrated for single‐stranded oligoribonucleotides. The transport was energy‐dependent, inhibited by GMP‐PNP and wheat germ agglutinin, but unaffected by N‐ethylmaleimide. Nuclear import of oligo(dG)25/protein adducts needed 3 to 4 oligonucleotide signals per complex and the signal had to be at least 15 nucleotides long. Micro‐injection experiments showed that the results obtained with digitonin‐permeabilized cells are not artifacts of a quasi‐intact cellular system. These data were confirmed by electron microscopy employing complexes of oligodeoxyribonucleotides with streptavidin‐peroxidase‐bovine serum albumin‐1 nm gold. In permeabilized cells, the complexes docked to the cytoplasmic face of the nuclear pore complexes, were translocated through the central pore channel and accumulated in large quantities in the nuclear baskets before they were released into the nucleoplasm. These results demonstrate that nuclear uptake of oligonucleotides and their complexes is an active process mediated by nuclear pore complexes, which, at least regarding its cytoplasmic component, is different from the pathway requiring classical nuclear localization signals.
Recurring themes in oocyte maturation
Authors: Maller James L.
Published: February 2012

I am pleased to contribute to this special issue of Biology of the Cell in honor of Yoshio Masui. Oocyte maturation remains a small enough and young enough field that the authors assembled for this issue can trace the entire development of the field over the last 30 years, beginning with the early demonstration by Masui (1967) and others that steroids can induce complete maturation of denuded oocytes in vitro. Not very long after that Masui and Markert (1971) published the seminal paper that identified MPF and CSF activity. In this article I intend to highlight recurring themes in oocyte maturation that continue to be actively investigated, almost all of which derive from studies pursued at some point in time by Masui and his colleagues.
Raf‐1 kinase, a potential regulator of intracellular pH in Xenopus oocytes
Authors: Kang Myoung‐Goo , Kulisz Andre , Wasserman William J
Published: February 2012

Xenopus laevis oocytes undergo an increase in intracellular pH (pHi) from 7.2 to 7.7 due to the upregulation of Na+/H+ antiporters in their plasma membrane during oocyte meiotic maturation. Up‐regulation of Na+/H+exchangers (NHE) found in other cell systems appears to be controlled, in some cases, by direct phosphorylation of the exchanger. A number of active protein kinases can be found in maturing Xenopus oocytes. These include, c‐mos kinase, Raf‐1 kinase, mitogen‐activated kinase kinase (MAPKK), MAPK, ribosomal S6 kinase (RSK), and histone H‐1 kinase. Our previous study indicated that c‐mos kinase, was involved in regulating the increase in oocyte pHi. In the current study, we show that when mRNA coding for a constitutively active form of Raf‐1 kinase (ΔN‐Raf‐1) was microinjected into oocytes, the protein product induced an increase in oocyte pHi. On the contrary, the injection of mRNA coding for wild‐type Raf‐1 (WT‐Raf‐1) or a kinase‐deficient form of Raf‐1 (KD‐Raf‐1) had no effect on the recipient oocyte pHi. 8‐Br‐cAMP and forskolin blocked the increase in pHi during oocyte meiotic maturation, but had no effect on the Raf‐1‐induced increase in oocyte pHi. Studies using antisense c‐mos oligos demonstrated that Raf‐1 was not working via a feedback loop to endogenous c‐mos mRNA within the recipient oocytes. Experiments using the selective MAPKK inhibitor, PD 98059, indicated that the Raf‐1 effect on oocyte pHi was not mediated by the downstream kinase, MAPKK. Therefore, Raf‐1 appears to act independently of c‐mos kinase in a pathway, not involving MAPKK, leading to the up‐regulation of the Na+/H+ antiporters in Xenopus oocytes.
Nuclear responses to MPF activation and inactivation in Xenopus oocytes and early embryos
Authors: Lohka Manfred J
Published: February 2012

The cell cycle of most organisms is highlighted by characteristic changes in the appearance and activity of the nucleus. Structural changes in the nucleus are particularly evident when a cell begins to divide. At this time, the nuclear envelope is disassembled, the chromatin condenses into metaphase chromosomes, and the chromosomes associate with a newly formed spindle. Upon completion of cell division the nuclear envelope reassembles around the chromosomes as they form telophase nuclei, and subsequently interphase nuclei, in the daughter cells. The cytoplasmic control of nuclear behavior has been the theme of Yoshio Masui's research for much of his career. His pioneering demonstration that the cytoplasm of maturing amphibian oocytes causes the resumption of the meiotic cell cycle when it is injected into an immature oocyte provided unequivocal evidence that a cytoplasmic factor could initiate the transition from interphase to metaphase (M‐phase) in intact cells. As described in several reviews in this and the previous issue of Biology of the Cell (see Beckhelling and Ford; Duesbery and Vande Woude; Maller), Masui initially called this activity maturation promoting factor (MPF), but when it was realized that it was a ubiquitous regulator of both mitotic and meiotic cell cycles, MPF came to stand for M‐phase promoting factor. Biochemical evidence indicates that MPF activity is composed of a mitotic B‐type cyclins and cyclin‐dependent kinase 1. The increase in the protein kinase activity of cdk1 initiates the changes in the nucleus associated with oocyte maturation and with the entry into mitosis. This article will attempt to provide a brief summary of the responses of the nucleus to the activation of MPF. In addition, the effect of MPF inactivation on nuclear envelope assembly at the end of mitosis will be discussed. This article is written as a tribute to Yoshio Masui on his retirement from the University of Toronto, and as an expression of gratitude for his guidance while I was a student in his laboratory. I have felt very privileged to have known him as a mentor and a friend.