bluuebunny/crossref_metadata_2025 huggingface dataset:
A Model for Circadian Rhythms in Drosophila Incorporating the Formation of a Complex between the PER and TIM Proteins
Authors: Leloup Jean-Christophe , Goldbeter Albert
Published: May 2004

The authors present a model for circadian oscillations of the Period (PER) and Timeless (TIM) proteins in Drosophila. The model for the circadian clock is based on multiple phosphorylation of PER and TIM and on the negative feedback exerted by a nuclear PER-TIM complex on the transcription of the perand tim genes. Periodic behavior occurs in a large domain of parameter space in the form of limit cycle oscillations. These sustained oscillations occur in conditions corresponding to continuous darkness or to entrainment by light-dark cycles and are in good agreement with experimental observations on the temporal variations of PER and TIM and of per and tim mRNAs. Birhythmicity (coexistence of two periodic regimes) and aperiodic oscillations (chaos) occur in a restricted range of parameter values. The results are compared to the predictions of a model based on the sole regulation by PER. Both the formation of a complex between PER and TIM and protein phosphorylation are found to favor oscillatory behavior. Determining how the period depends on several key parameters allows us to test possible molecular explanations proposed for the altered period in the perl and pers mutants. The extended model further allows the construction of phase-response curves based on the light-induced triggering of TIM degradation. These curves, established as a function of both the duration and magnitude of the effect of a light pulse, match the phase-response curves obtained experimentally in the wild type and pers mutant of Drosophila.
The Suprachiasmatic Nucleus: A 25-Year Retrospective
Authors: Weaver David R.
Published: May 2004

The suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain the master circadian pacemaker in mammals. On the occasion of the 25th anniversary of the discovery of the SCN as the circadian clock, Charles A. Czeisler and Steven M. Reppert organized a meeting to review milestones and recent developments in the study of the SCN. The discovery that the SCN contain tissue necessary for generation of circadian rhythmicity was established by lesion studies published in 1972. The second phase of study demonstrated unequivocally that the SCN contain an autonomous circadian pacemaker. The principal studies in this period showed the presence of metabolic and electrical activity rhythms in the SCN in vivo and progressed to studies showing that the SCN maintain rhythmicity in vitro, demonstrating that the transplanted SCN can restore circadian function following destruction of the host SCN and ultimately showing that single SCN “clock cells” exhibit independent rhythms in firing rate. The third phase of study, aimed at identifying the biochemical and molecular mechanisms responsible for rhythmicity within the SCN, has begun with the identification of circadian mutants ( tau mutant hamsters and Clock mutant mice) and the isolation of the Clock gene. This report traces the important steps forward in our understanding of the suprachiasmatic circadian clock by recounting the information presented at the SCN Silver Anniversary Celebration.
Isolation and Chronobiological Analysis of a Neuropeptide Pigment-Dispersing Factor Gene in Drosophila melanogaster
Authors: Park Jae H. , Hall Jeffrey C.
Published: May 2004

In this article, the authors isolate a gene encoding a neuropeptide in Drosophila melanogaster. The substance is called pigment-dispersing factor (PDF), based on one of the roles it plays in crustaceans (the arthropods in which this factor was initially discovered). The PDF-encoding Drosophila gene ( pdf) is intronless and present in a single copy per haploid genome. The cytological location of pdf is 97B on the third chromosome. The putative 102-amino-acid precursor (prepro-PDF) consists of a signal peptide and a PDF-associated peptide, followed by the mature PDF. The PDF-associated peptide region of the precursor is highly diverged from those of the crustacean precursors, whereas the primary structure of the mature PDF is conserved in other members of the pigment-dispersing hormone family. A single pdf transcript (ca. 0.8 kb) is expressed predominantly in the head; the expression levels of pdf mRNA are consistently higher in males than in females. Putative pdf homologous transcripts are present in other Drosophila species, which exhibit similar sexual dimorphic expression patterns. Cyclic expression of pdf over the course of the day and night was assessed, but the mRNA exhibited at best very gentle cycling. The pdfexpression in two behaviorally arrhythmic mutants were examined; the expression was intact in a period0 mutant but absent in the disconnected mutant.
Photoperiod, Ambient Temperature, and Food Availability Interact to Affect Reproductive and Immune Function in Adult Male Deer Mice (Peromyscus maniculatus)
Authors: Demas Gregory E. , Nelson Randy J.
Published: May 2004

Winter is often stressful. Increased energetic demands in winter and concurrent reductions in energy availability can lead to an energetic imbalance and compromise survival. To increase the odds of surviving winter, individuals of some nontropical rodent species have evolved mechanisms to enhance immune function in advance of harsh winter conditions. Short day lengths provide a proximate cue for enhancement of immune function, an adaptive functional response to counter environmental stress-induced reduction in immune function. In the present study, photoperiod, ambient temperature, and food availability were manipulated and reproductive function and cell-mediated immunity were assessed in adult male deer mice ( Peromyscus maniculatus). Mice maintained in short days regressed their reproductive systems and displayed enhanced immune function compared to long-day animals. Reduced food availability elevated corticosterone concentrations and suppressed reproductive and immune function, whereas ambient temperature alone had no effect on cell-mediated immunity. The suppressive effect of food restriction on reproductive and immune function was overcome by maintaining animals in short days. However, short-day, food-restricted mice maintained at low ambient temperatures displayed reduced reproductive and immune function compared to animals maintained at mild temperatures. Taken together, these results suggest that short-day enhancement of immune function can counteract some, but not all, of the immunosuppressive effects of winter stressors. These data are consistent with the hypothesis that immune function is enhanced in short days to counteract stress-mediated immune suppression occurring during winter.
Induction of Circadian Rhythm of Feeding Activity by Testosterone Implantations in Arrhythmic Japanese Quail Males
Authors: Lumineau Sophie , Guyomarc’h Catherine , Boswell Tim , Richard Jean-Pierre , Leray David
Published: May 2004

Studies in vertebrates have shown that hormones can influence circadian rhythms of behavior. We investigated whether testosterone could induce rhythmicity in arrhythmic Japanese quail, kept in DD. The animals used were 31/2-week-old castrated males from a line of quail selected for the lack of the circadian rhythm of feeding activity. After 3 weeks in DD, 8 birds were implanted with an empty implant and 16 others with a testosterone implant. Two weeks later, the operation was repeated. After implantation, we noticed that 15 out of 16 testosterone-treated birds showed a circadian rhythm of feeding activity, in contrast to the control birds, which remained arrhythmic. The clarity of this rhythm increased significantly after each implantation. A positive correlation was found between the indexes of clarity of the rhythm (autocorrelation coefficient ratio and area of the peak of spectrum) and the plasma testosterone level. The period of the induced free-running rhythm was identical to the specific value of the endogenous circadian rhythm in immature quail. The circadian period showed a significant lengthening with the second implantation. This lengthening looks like the variation previously observed in maturing rhythmic or implanted quail. So, it would appear that testosterone can act on rhythmicity on at least two levels: by inducing the circadian rhythm and increasing its clarity and by modulating its period. To explain these results, several hypotheses can be considered. First, the observed arrhythmy may be the consequence of an internal desynchronization of oscillators, responsible for generating the circadian rhythm of feeding activity, and testosterone could play a role in the coupling of these oscillators. Alternatively, we suggest that testosterone could act on the transcription of genes implicated in the control of the rhythmicity or may regulate by rapid signals the cellular rhythmic activity. The possible functional values of the enhancing of circadian rhythmicity by testosterone at different stages of the bird's life were discussed.
Daily Variations in Pineal Melatonin Concentrations in Inbred and Outbred Mice
Authors: Vivien-Roels Berthe , Malan André , Rettori Marie-Claire , Delagrange Philippe , Jeanniot Jean-Philippe , Pévet Paul
Published: May 2004

Melatonin was measured using a specific radioimmunoassay in 1 strain of outbred mice (OF1 Swiss) and 4 strains of inbred mice, 2 of them being known to synthesize melatonin (CBA and C3H) and the 2 others being controversial (BALB/c and C57BL/6). In this study, the 5 mouse strains were able to synthesize melatonin, but the basal levels as well as the diurnal variations were very different from one strain to another. CBA and C3H strains showed a clear-cut day-night rhythm of pineal melatonin concentration, with peak levels of 276 ± 22 pg/pineal in CBA and 135 ± 12 pg/pineal in C3H. In BALB/c, the authors confirmed the presence of a very short melatonin peak (15 min) in the middle of the dark period. In C57BL/6 and OF1 Swiss, a very small but significant peak was observed in the middle of the darkness. In the former, another small peak was also observed at light onset. Whether these very small peaks, which may be related to the deficience of N-acetyl transferase activity reported by others, have a physiological meaning remains to be determined.
Spermidine Determines the Sensitivity to the Calmodulin Antagonist, Chlorpromazine, for the Circadian Conidiation Rhythm but Not for the Mycelial Growth in Neurospora crassa
Authors: Katagiri Satoshi , Onai Kiyoshi , Nakashima Hideaki
Published: May 2004

The gene that suppresses the phenotype of the cpz-2mutation, which results in changing the sensitivity to chlorpromazine in relation to mycelial growth and circadian rhythms, was cloned in Neurospora crassa.This gene is not the cpz-2 gene itself but rather is identical to the spe-3gene that encodes spermidine synthase in Neurospora. The intracellular content of spermidine was lowered in the cpz-2strain compared to that of the wild-type strain. By integration of the spe-3 gene or by the addition of spermidine into culture medium, the temperature sensitivity of mycelial growth was lost and the conidiation rhythm became sensitive to chlorpromazine in the cpz-2 strain, as was observed in the wild-type strain, but the hypersensitivity of mycelial growth on chlorpromazine in the cpz-2strain was not affected. Therefore, it appears that spermidine determines only the sensitivity of the conidiation rhythm to chlorpromazine.
Effects of Circadian Mutations and LD Periodicity on the Life Span of Drosophila melanogaster
Authors: Klarsfeld André , Rouyer François
Published: May 2004

The pervasive occurrence of circadian clocks throughout the living world underlines their adaptive value. Nonetheless, there is surprisingly little evidence for a negative impact, on any animal species, of a constant discrepancy between the environmental and endogenous periods. Male Drosophila melanogaster per mutants with altered circadian periods were compared to the wild type in two different LD schedules. Life span was used as a global index of physiological adaptation. The life span of the mutants was significantly reduced by up to 15% for the flies whose period differs most from that of the wild type. A reduction was observed even when flies were kept in an LD schedule fitting a mutant period. The LD schedule made no significant difference on its own, but the authors found evidence for an interaction between genotype and LD schedule in determining life span. These results are consistent with the importance of the circadian clock in maintaining internal temporal order independent of environ-mental cycles. Nonetheless, a large difference between the environmental and endogenous periods has a measurable impact.
Serotonin Agonist Quipazine Induces Photic-Like Phase Shifts of the Circadian Activity Rhythm and c-Fos Expression in the Rat Suprachiasmatic Nucleus
Authors: Kohler Markus , Kalkowski Andreas , Wollnik Franziska
Published: May 2004

Nonphotic stimuli can reset and entrain circadian activity rhythms in hamsters and mice, and serotonin is thought to be involved in the phase-resetting effects of these stimuli. In the present study, the authors examined the effect of the serotonin agonist quipazine on circadian activity rhythms in three inbred strains of rats (ACI, BH, and LEW). Furthermore, they investigated the effect of quipazine on the expression of c-Fos in the mammalian circadian pacemaker, the suprachiasmatic nucleus (SCN). Quipazine reduced the amount of running wheel activity for 3 h after treatment, however, no long-term changes in τ and in the activity level were observed. More important, quipazine induced significant phase advances of the activity rhythm and c-Fos production in the SCN at the end of the subjective night (Circadian Time [CT] 22), whereas neither phase shifts nor c-Fos induction were observed during the subjective day. Quipazine injections also resulted in moderate phase delays at the beginning of the subjective night (CT 14). A similar phase-response characteristic typically can be observed for photic stimuli. By contrast, nonphotic stimuli normally produce phase advances during the subjective day. The present results suggest species differences between the hamster and the rat with respect to the serotonergic action on circadian timekeeping and indicate that serotonergic pathways play a role in the transmission of photic information to the SCN of rats.
Influence of Pinealectomy and Pineal Stalk Deflection on Circadian Gastrointestinal Tract Melatonin Rhythms in Zebra Finches (Taeniopygia guttata)
Authors: Van't Hof Thomas J. , Gwinner Eberhard
Published: May 2004

The authors examined levels of melatonin in the plasma and various tissues in intact, pinealectomized, and pineal stalk–deflected zebra finches kept under 12:12 LD to determine if the melatonin found in the gastrointestinal tract is secreted in a circadian manner. In intact and pineal stalk-deflected birds, there is a clear day-night rhythm in melatonin content of the plasma, pineal gland, eyes, proventriculus, crop, duodenum, jejunum/ileum, colon, heart, and liver. In contrast, pinealectomy abolished the day-night rhythm. These results indicate that most of the melatonin present in the gastrointestinal tract of zebra finches is of pineal origin. However, some melatonin remained. This suggests that this melatonin may be locally synthesized and has paracrine and/or autocrine functions. Nonetheless, the results do not lend support to the contention that this putative melatonin secretion by the gastrointestinal tract is circadian.
Light and Diurnal Cycle Affect Human Heart Rate: Possible Role for the Circadian Pacemaker
Authors: Scheer Frank A.J.L. , van Doornen Lorenz J. P. , Buijs Ruud M.
Published: May 2004

Humans and animals demonstrate diurnal rhythms in physiology and behavior, which are generated by the circadian pacemaker, located in the supra-chiasmatic nucleus (SCN). The endogenous diurnal rhythm of the SCN is synchronized to the diurnal cycle most effectively by light. However, light also influences the SCN and its output instantaneously, as is demonstrated for the immediate effects of light on SCN neuronal firing frequency and on the output of the SCN to the pineal, inhibiting melatonin secretion. In addition to this, the circadian pacemaker modulates neuronally also other organs such as the adrenal. Therefore, the authors investigated the effect of this light input to the SCN on human heart rate, using light at different phases of the day-night cycle and light of different intensities. Resting heart rate (HR) was measured in volunteers between 20 and 40 years of age during supine, awake, resting conditions, and after 2 hours of fasting. In Experiment 1, HR was measured at different times over the day-night cycle at 0 lux and at indoor light. In Experiment 2, HR was measured at different times over the day-night cycle at controlled light intensities of 0 lux, 100 lux, and 800 lux. The authors demonstrate a clear diurnal rhythm in resting HR in complete darkness, similar to that measured under constant routine conditions. Second, it is demonstrated that light increases resting HR depending on the phase of the day-night cycle and on the intensity of light. These data strongly suggest that the circadian pacemaker modulates human HR.
The Endogenous Melatonin Profile as a Marker for Circadian Phase Position
Authors: Lewy Alfred J. , Cutler Neil L. , Sack Robert L.
Published: May 2004

Several circadian rhythms have been used to assess the phase of the endogenous circadian pacemaker (ECP). However, when more than one marker rhythm is measured, results do not always agree. Questions then inevitably arise. Are there multiple oscillators? Are some markers more reliable than others? Masking is a problem for all marker rhythms. Masking of melatonin is minimized by sampling under dim light. The dim-light melatonin onset (DLMO) is particularly convenient since it can usually be obtained before sleep. However, assessing the DLMO in low melatonin producers may be problematic, particularly with the commonly used operationally defined threshold of 10 pg/ml. This study evaluates various circadian phase markers provided by the plasma melatonin profile in 14 individuals, several of whom are low melatonin producers. The amount (amplitude) of melatonin production appears to influence the phase of many points on the melatonin profile. Accordingly, when low producers are in a data set, we now prefer a lower DLMO threshold than the one previously recommended (10 pg/ml). Indeed, there are some low producers who never exceed this threshold at any time. Radioimmunoassays are now available that have the requisite sensitivity and specificity to support the use of a lower threshold. Nevertheless, the dim-light melatonin offset (DLMOff), even when operationally defined at thresholds less than 10 pg/ml, appears to be confounded by amplitude in this study; in such cases, it may be preferable to use the melatonin synthesis offset (SynOff) because it is not confounded by amplitude and because, theoretically, it is temporally closer to the endogenous mechanism signaling the offset of production. The question of whether the termination mechanism of melatonin synthesis is related to an interval timer or to a second oscillator loosely coupled to the onset oscillator is probably best answered using the SynOff rather than the DLMOff. It is hoped that these findings will make a useful contribution to the debate on the best ways to use points on the melatonin profile to assess circadian phase position in humans.
Seasonal Variation of Blood Cholesterol Levels: Study Methodology
Authors: Merriam Philip A. , Ockene Ira S. , Hebert James R. , Rosal Milagros C. , Matthews Charles E.
Published: May 2004

This manuscript provides a description of the methodology used in the Seasonal Variation of Blood Cholesterol Levels (SEASON) study, with the intent of informing the scientific community of the available data sets and to invite a dialogue with scientists in complementary fields. The primary aim of the SEASON study is to describe and delineate the causes of seasonal variation of blood lipid levels in the general population. This research project is designed specifically to systematically collect and analyze a number of important variables necessary to study the role of seasonality in blood lipids and relevant covariates.
Short Day Lengths Affect Perinatal Development of the Male Reproductive System in the Siberian Hamster, Phodopus sungorus
Authors: Hegstrom Carol D. , Breedlove S. Marc
Published: May 2004

The Siberian hamster, Phodopus sungorus, breeds seasonally. In the laboratory, seasonal breeding can be controlled by photoperiod, which affects the duration of nightly melatonin secretion. Winterlike, short day lengths induce gonadal regression in adult animals, and pups born and maintained in short days undergo pubertal gonadal development later than animals born into long days. However, to date there have been no reports of gestational photoperiod affecting fetal development of reproductive systems. The spinal nucleus of the bulbocavernosus (SNB) and its target muscles, the bulbocavernosus (BC) and levator ani (LA), compose a sexually dimorphic, androgen-sensitive neuromuscular system involved in male reproduction. The SNB neuromuscular system was studied in male Siberian hamsters maintained from conception in short-day (8 h light, 16 h dark; 8L:16D) versus long-day (16L:8D) conditions. On the day of birth, and at postnatal(PN) days 2 and 18, the BC/LA muscles of hamsters gestated and raised in the short photoperiod were significantly reduced relative to those of their long-day counterparts. Testes weights were not significantly different between groups until day 18. Thus, photoperiod exposure during gestation and after birth affects perinatal development of the SNB system in this species, and these effects can be seen as early as the day of birth. Because photoperiod did not significantly affect testes weights until PN18, these results suggest that either perinatal photoperiod affects fetal androgen production without affecting testes weight or it influences BC/LA development independently from androgen.
Thermoregulatory Model of Sleep Control: Losing the Heat Memory
Authors: Nakao Mitsuyuki , McGinty Dennis , Szymusiak Ronald , Yamamoto Mitsuaki
Published: May 2004

Thermoregulatory mechanisms were hypothesized to provide primary control of non-rapid-eye-movement sleep (NREM). On the basis of this hypothesis, we incorporated the thermoregulatory feedback loops mediated by the “heat memory,” heat load, and loss processes associated with sleep-wake cycles, which were modulated by two circadian oscillators. In addition, hypnogenic warm-sensitive neurons (HWSNs) were assumed to integrate thermoregulation and NREM control. The heat memory described above could be mediated by some sleep-promoting substances. In this paper, considering the possible carrier of the heat memory, its losing process is newly included in the model. The newly developed model can generate the appropriate features of human sleepwake patterns. One of the special features of the model is to generate the bimodal distribution of the sleepiness. This bimodality becomes distinct, as the losing rate of the heat memory decreases or the amplitude of the Y oscillator increases. The theoretical analysis shows the losing rate of the heat memory control's rapidity of model response to a thermal perturbation, which is confirmed by simulating the responses with various losing rates to transient heat loads (“heat load pulse”). The sleepiness exhibits large responses to the heat load pulses applied in the early and late phases of wake period, while the response is significantly reduced to the pulse applied in the supposed wake-maintenance zone. This bimodality of the response appears to reflect the sensitivity of the HWSNs. In addition, the early pulse raises the immediate sleepiness rather than the nocturnal sleepiness, while the heat load pulse applied in the later phase of waking period significantly raises the sleepiness during a nocturnal sleep. In simulations of sleep deprivation, the discontinuous relationship between recovery sleep length and deprivation time is reproduced, where the critical sleep deprivation time at which the recovery sleep length jumps is extended as the losing rate increases. This is possibly due to the dissipation of the heat memory accumulated by the sleep deprivation. The simulation results here qualitatively reproduce the experimental observations or predict the intriguing phenomena of human circadian rhythms. Therefore, our model could provide a novel framework for investigating the relationship between thermoregulation and sleep control processes.
Commentary: Future Considerations for Models of Human Neurobehavioral Function
Authors: Dinges David F. , Achermann Peter
Published: May 2004

Modeling human neurobehavioral functions has the goal of identifying work-rest schedules that are safer and more productive. The models of Folkard et al. and of Jewett and Kronauer illustrate excellent progress toward this goal. Examination of these models reveals four additional areas that need to be addressed to facilitate continued development of accurate models of neurobehavioral functions. (1) The choice of neurobehavioral metrics may have a significant influence on model development. The lack of correlation among different neurobehavioral measures may make comparisons of models difficult. Many neurobehavioral measures are confounded by secondary and random error variance that can lead to model distortion. Although different models may ultimately be required for different neurobehavioral functions, measures that have been extensively validated to be sensitive to circadian variation and sleep loss should take priority in model development. (2) Because error variance in neurobehavioral outcomes can be substantial in uncontrolled environments, model validation should proceed from controlled laboratory protocols to real-world scenarios. Once validated, the ability of a model to predict field data can be tested. (3) While neurobehavioral models have been developed to predict behavior over time (i.e., within-subjects), to be useful in the real world, models will also ultimately have to provide estimates of between-subject variation in vulnerability to neurobehavioral dysfunction during night work or sleep loss (e.g., younger versus older workers). (4) Finally, to be theoretically accurate and practically useful, models of human neurobehavioral functions should be able to predict both cumulative effects (i.e., across days or weeks) and the influence of countermeasures (e.g., light, naps, caffeine).
Limit Cycle Models for Circadian Rhythms Based on Transcriptional Regulation in Drosophila and Neurospora
Authors: Leloup Jean-Christophe , Gonze Didier , Goldbeter Albert
Published: May 2004

We examine theoretical models for circadian oscillations based on transcriptional regulation in Drosophila and Neurospora. For Drosophila, the molecular model is based on the negative feedback exerted on the expression of the per and tim genes by the complex formed between the PER and TIM proteins. For Neurospora, similarly, the model relies on the feedback exerted on the expression of the frq gene by its protein product FRQ. In both models, sustained rhythmic variations in protein and mRNA levels occur in continuous darkness, in the form of limit cycle oscillations. The effect of light on circadian rhythms is taken into account in the models by considering that it triggers degradation of the TIM protein in Drosophila, and frq transcription in Neurospora. When incorporating the control exerted by light at the molecular level, we show that the models can account for the entrainment of circadian rhythms by light-dark cycles and for the damping of the oscillations in constant light, though such damping occurs more readily in the Drosophila model. The models account for the phase shifts induced by light pulses and allow the construction of phase response curves. These compare well with experimental results obtained in Drosophila. The model for Drosophila shows that when applied at the appropriate phase, light pulses of appropriate duration and magnitude can permanently or transiently suppress circadian rhythmicity. We investigate the effects of the magnitude of light-induced changes on oscillatory behavior. Finally, we discuss the common and distinctive features of circadian oscillations in the two organisms.
Circadian Systems and Metabolism
Authors: Roenneberg Till , Merrow Martha
Published: May 2004

Circadian systems direct many metabolic parameters and, at the same time, they appear to be exquisitely shielded from metabolic variations. Although the recent decade of circadian research has brought insights into how circadian periodicity may be generated at the molecular level, little is known about the relationship between this molecular feedback loop and metabolism both at the cellular and at the organismic level. In this theoretical paper, we conjecture about the interdependence between circadian rhythmicity and metabolism. A mathematical model based on the chemical reactions of photosynthesis demonstrates that metabolism as such may generate rhythmicity in the circadian range. Two additional models look at the possible function of feedback loops outside of the circadian oscillator. These feedback loops contribute to the robustness and sustainability of circadian oscillations and to compensation for long-and short-term metabolic variations. The specific circadian property of temperature compensation is put into the context of metabolism. As such, it represents a general compensatory mechanism that shields the clock from metabolic variations.
The Goodwin Oscillator: On the Importance of Degradation Reactions in the Circadian Clock
Authors: Ruoff Peter , Vinsjevik Merete , Monnerjahn Christian , Rensing Ludger
Published: May 2004

This article focuses on the Goodwin oscillator and related minimal models, which describe negative feedback schemes that are of relevance for the circadian rhythms in Neurospora, Drosophila, and probably also in mammals. The temperature behavior of clock mutants in Neurospora crassa and Drosophila melanogaster are well described by the Goodwin model, at least on a semi-quantitative level. A similar semi-quantitative description has been found for Neurospora crassa phase response curves with respect to moderate temperature pulses, heat shock pulses, and pulses of cycloheximide. A characteristic feature in the Goodwin and related models is that degradation of clock-mRNA and clock protein species plays an important role in the control of the oscillator's period. As predicted by this feature, recent experimental results from Neurospora crassa indicate that the clock (FRQ) protein of the long period mutant frq7 is degraded approximately twice as slow as the corresponding wild-type protein. Quantitative RT-PCR indicates that experimental frq7 -mRNA concentrations are significantly higher than wild-type levels. The latter findings cannot be modeled by the Goodwin oscillator.Therefore,athresholdinhibitionmechanismoftranscriptionis proposed.
pH-Sensitive Hydrogels Composed of Chitosan and Polyacrylamide: Enzymatic Degradation
Authors: Bonina P. , Petrova T. , Manolova N. , Rashkov I. , Naydenov M.
Published: May 2004

The enzymatic degradation of three types of pH-sensitive hydrogels, composed of the natural polyaminosaccharide chitosan and polyacrylamide, was studied. The weight of the films that were made with net-PAAm- i-chitosan, net-chitosan- i-PAAm and net-chitosan- net-PAAm decreased in the presence of the Trichoderma viride enzyme complex ; thus, the chitosan in the composite retained its degradability after crosslinking. The rate of enzymatic degradation depended on the structure of the network, on the amount of crosslinking agents, on the pH of the medium and on the temperature. Crosslinked chitosan alone degraded slower than net-chitosan- i-PAAm; this was attributed to the facilitated penetration of enzyme by the water-soluble PAAm in the semi-IPNs. T. viride embedded in chitosan/PAAm films or beads developed and reproduced normally. However, T. viride embedded in net-chitosani-PAAm developed considerably slower, and development was not detected in the case of net-PAAm- i-chitosan. All of the networks proved to be appropriate carriers of Bacillus subtilis.
Managing Growth: Recent Legal Literature
Authors: Starkweather Sarah , Low Adrienne , Pearlman Kenneth
Published: May 2004

As development pressures increase and as undeveloped land disappears at an increasing rate, growth management and regulation have become significant themes in land use planning. Using the perspective of legal literature, this article examines many ideas that have an impact on these themes, with an emphasis on important conceptual and legal issues. Specific state initiatives are a focus, as is the role of regional programs. The federal government also plays its part. In addition, the article examines the relationship between growth management and such areas as biodiversity and endangered species, water policy, and farmland preservation. The article concludes with a final inquiry into the legal limitations that can shape growth management policy.
Environmental Injustice and Transportation: The Claims and the Evidence
Authors: Schweitzer Lisa , Valenzuela Abel
Published: May 2004

Belief that transportation investment and operations have caused environmental damage in poor and minority communities to benefit the more affluent has prompted planning agencies to craft policies aimed at promoting environmental justice. Yet, we have only scattered evidence about the distribution of the costs and benefits derived from transportation policy, investment, and planning. This article creates a framework based in distributive justice for categorizing the existing research into cost-based and benefit-based claims of injustice. The authors go on to synthesize the cost-based research, which measures the distribution of pollution and hazards from transportation. From this survey, myriad research opportunities emerge.
The Role of Mother Involvement and Father Involvement in Adolescent Bullying Behavior
Authors: Flouri Eirini , Buchanan Ann
Published: May 2004

It has been suggested that bullying behavior at school may be linked to parenting and family characteristics. Based on data from 1,147 adolescents aged 14 to 18 years in Britain, this study explored whether father involvement can protect against offspring bullying behavior. Results showed that low father involvement and low mother involvement contributed significantly and independently to bullying behavior in adolescents. Neither the association between father involvement and bullying nor the one between mother involvement and bullying was higher for sons than for daughters. There was evidence showing that the impact of the father-child relationship depended on the closeness of the mother-child relationship in that father involvement protected more when mother involvement was lower.
Evaluation of a National Prison-based Treatment Program for Sexual Offenders in England and Wales
Authors: Friendship Caroline , Mann Ruth E. , Beech Anthony R.
Published: May 2004

Treatment efficacy is described for a sample of sexual offenders who had undertaken treatment in United Kingdom prisons (N = 647) and for a retrospectively selected comparison group (N = 1,910). The outcomes under observation in this study were sexual, sexual and/or violent, and general reconviction. Treatment impact was also examined in relation to offenders' risk of reconviction. The treatment group had slightly lower 2-year sexual reconviction rates than the comparison group, but these differences were not statistically significant. Significant differences were found between the treatment and comparison group for sexual and/or violent reconviction. Further analysis suggested that treatment produced a reduction in the probability of sexual and/or violent reconviction (p <. 05) when other relevant variables were controlled for. General reconviction rates were consistently lower in the treatment group, but these differences were not significant.
Psychopathological Profile of Men Convicted of Gender Violence
Authors: Echeburúa Enrique , Fernández-Montalvo Javier , Amor Pedro J.
Published: May 2004

In this article, a description of the demographic, penal, and psychopathological characteristics of 54 men who are in prison because of having committed a serious offense of gender violence was carried out. Furthermore, a comparison of all the variables studied between the participants with homicide and those without homicide was done. The results showed the existence of irrational beliefs both about women and violence as a strategy to cope with everyday difficulties, as well as a general inadaptation to daily life. However, from a psychopathological point of view, in spite of not observing a high degree of symptomatology in the sample, the psychiatric and penal antecedents and current emotional instability were much more frequent and severe in people who had not committed homicide. Therefore, two possible differential profiles among the violent men are presented.
The Relationship Between the Quantity of Alcohol Consumed and the Severity of Sexual Assaults Committed by College Men
Authors: Abbey Antonia , Clinton-Sherrod A. Monique , McAuslan Pam , Zawacki Tina , Buck Philip O.
Published: May 2004

Researchers have suggested that intoxicated perpetrators may act more violently than other perpetrators, although empirical findings have been mixed. Past research has focused on whether or not alcohol was consumed, rather than the quantity consumed, and this may explain these inconsistent findings. The authors hypothesized that the quantity of alcohol consumed would have a curvilinear relationship to the severity of the assault. Data were collected from 113 college men who reported that they had committed a sexual assault since the age of 14. The quantity of alcohol that perpetrators consumed during the assault was linearly related to how much aggression they used and was curvilinearly related to the type of sexual assault committed. The quantity of alcohol that victims consumed during the assault was linearly related to the type of sexual assault committed. Strategies for improving assessment of alcohol consumption in sexual assault research are discussed.
To Leave or to Stay?
Authors: Faver Catherine A. , Strand Elizabeth B.
Published: May 2004

Consistent with previous research, almost half of a sample of 41 pet-owning battered women reported that their partners had threatened or actually harmed their pets, and over a fourth reported that concern for their pets had affected their decisions about leaving or staying with the batterer. Differences between rural and urban women were not significant, although higher proportions of rural than urban women reported that their partners had threatened or harmed their pets and that concern for their pets had affected their decisions. For the sample as a whole, logistic regression analyses showed that women whose pets had been threatened or harmed were significantly more likely to report that concern for their pets had affected their decisions about leaving or staying. The findings suggest that service providers should inquire about battered women’s concern for their pets and should include arrangements for animals in safety planning.
Contextualizing Depression and Physical Functioning in Battered Women
Authors: Nurius Paula S. , Macy Rebecca J. , Bhuyan Rupaleem , Holt Victoria L. , Kernic Mary A. , Rivara Frederick P.
Published: May 2004

This investigation examined the relationships between physical, psychological, and sexual abuse along with vulnerability appraisals, positive and negative social relations, and socioeconomic resources on battered women’s depression symptomatology and physical functioning. Women were recruited following an incident of partner violence that resulted in a police-report or the filing of a protection order. Participants were surveyed using a standardized questionnaire. Bivariate correlations and multiple regressions were used to examine the relationships between predictors as well as the cumulative and unique contributions of each variable set in explaining depression and physical functioning. Findings indicate that vulnerability appraisals, social relations, and socioeconomic resources significantly explain women’s depression and physical functioning over and above the unique effect of specific types of partner violence. Given that women’s physical and mental health are important aspects of assisting women with safety planning and violence cessation strategies, implications for assessment and interventions for battered women are discussed.
The Epidemiology of Female Rape Victims Who Seek Immediate Medical Care
Authors: Magid David J. , Houry Debra , Koepsell Thomas D. , Ziller Andrew , Soules Michael R. , Jenny Carole
Published: May 2004

Women who seek medical care following sexual assault are usually evaluated and treated in an emergency department (ED). Therefore, EDs can be an important source of sexual assault surveillance data. The authors compared the incidence of sexual assault presenting for emergency care in a single county during July to November of 1974 and 1991. Participants included all female sexual assault victims aged 14 and older who presented for ED evaluation. Treating physicians prospectively collected data using standardized forms. The z statistic was used to compare sexual assault incidence. There was a 60% increase in the incidence of sexual assault victims presenting for emergency care in 1991 compared to 1974, primarily due to an increase in the incidence of women presenting to the ED after rapes by known assailants. In contrast, the annual incidence of reported stranger assaults was similar in the two study years.
A Statewide Evaluation of Services Provided to Rape Survivors
Authors: Wasco Sharon M. , Campbell Rebecca , Howard April , Mason Gillian E. , Staggs Susan L. , Schewe Paul A. , Riger Stephanie
Published: May 2004

This article presents the descriptive results of a statewide evaluation of hotline, advocacy, and counseling services provided to sexual assault victims in Illinois. Collaborative efforts of a multidisciplinary research team and sexual assault service providers resulted in victim-sensitive evaluation measures and data that reflect, for the first time, the collective impact of services on rape victims across the state of Illinois. Results of the evaluation suggest that, overall, services provided to rape victims provided support, increased information and knowledge, and helped victims to understand options and make decisions. The evaluation approach is notable for its collaborative nature and its sensitivity to rape victims during help-seeking and delivery; however, due to the high levels of distress common among rape survivors, some evaluation methods may not be appropriate for crisis intervention services such as hotline or advocacy. Implications for future evaluation research and policy are noted.
An Exploratory Study of Child Molesters’ Relationship Patterns Using the Core Conflictual Relationship Theme Method
Authors: Drapeau Martin , de Roten Yves , Körner Annett C.
Published: May 2004

This study examined the relationship patterns of N = 20 child molesters (CM) using the Core Conflictual Relationship Theme (CCRT) method. The relationship patterns of the CMs were compared with those of a control group of N = 20 subjects from an out patient counseling service. Results showed that CMs had significantly less wish to be controlled, hurt, and not responsible than the control group. No significant difference was found between both groups for the CCRT response of other component (RO). For the response of self (RS) component, results indicated that CMs reported more relationship episodes in which they felt respected and accepted and self-controlled and self-confident. The authors suggest that these interactions could be indicators of the CMs’attempts to attribute blame to others andpresent themselves as victims. It is also suggested that CMs may have core issues involving autonomy and control.
Ambivalence of Nonoffending Guardians after Child Sexual Abuse Disclosure
Authors: Bolen Rebecca M. , Lamb J. Leah
Published: May 2004

A concern in the intervention with sexually abused children is the support of their nonoffending guardians after disclosure of the abuse. Approximately a third of nonoffending guardians respond with vacillation in support, and these nonoffending guardians are at greater risk for having their children removed. This article reconceptualizes vacillation in support as an ambivalent response. Drawing on the interdisciplinary literature, this article suggests that ambivalence in support reflects the confluence between the nonoffending guardian’s valence toward the child and perpetrator. This article further proposes that ambivalence is normative when the costs of disclosure are high and when the nonoffending guardian is ambivalent/preoccupied in attachment. Ambivalence may also be both a precursor to and an effect of the traumatic experience of the disclosure on the nonoffending guardian. In a study of 30 nonoffending mothers whose partners sexually abused their children, these relationships were supported.
Between Normality and Deviance
Authors: Buchbinder Eli , Eisikovits Zvi
Published: May 2004

With the transformation of intimate violence from private trouble to social problem, police intervention in domestic violence cases became more prevalent. Research has focused mainly on battered women’s perception of police intervention, their evaluations, and their level of satisfaction with the intervention. However, there is little research examining the perpetrators’ subjective perceptions of such interventions. The purpose of this study is to describe and analyze battering men’s perceptions of police intervention. The study is based on semistructured, in-depth interviews with 20 batterers who had repeated encounters with police. Findings show a continuum of self-management, ranging from attempts to preserve a normative identity in the first encounter to struggling against criminalization in the second encounter and adopting a victim identity in the third encounter. The findings are discussed in the context of gender identity and power relations.
Self-Injurious Behaviors, PTSD Arousal, and General Health Complaints Within a Treatment-Seeking Sample of Sexually Abused Women
Authors: Weaver Terri L. , Chard Kathleen M. , Mechanic Mindy B. , Etzel Julie C.
Published: May 2004

Eighty-nine adult female survivors of childhood sexual abuse, presenting for psychological treatment, were assessed for self-reported rates of self-injurious behaviors (SIB), health complaints, and posttraumatic stress disorder (PTSD) symptoms of physiological arousal. A composite measure of current SIB was significantly and positively associated with health complaints, PTSD arousal, and three measures of sexual abuse severity: age of onset for sexual abuse, injury experienced during the sexual abuse, and perceived life threat. Tests of mediation revealed that symptoms of PTSD arousal mediated the relationship between earlier age of onset for sexual abuse and SIB. PTSD arousal moderated the relationship between sexual-abuse-related injury and SIB. SIB was a unique predictor of health complaints, even after controlling for sexual abuse severity and PTSD arousal.
Domestic Violence in Puerto Rican Gay Male Couples
Authors: Toro-Alfonso JosÉ , RodrÍGuez-Madera Sheilla
Published: May 2004

Domestic violence (DV) is a pattern of behaviors in the context of an intimate relationship, which can be manifested in emotional, physical, or sexual abuse. DV currently represents a social and a public health issue. This study is an effort to foster a better understanding of DV among same-sex couples. In it, the authors included the participation of 199 Puerto Rican gay males to identify prevalence of DV, violence in their family of origin, participants’ addictive behaviors and exposure to violence at childhood, and their conflict resolution skills. Participants were relatively young, highly educated Puerto Rican gay men who reported a high level of domestic violence in their relationships. This violence was identified as emotional violence by 48% of the participants. This sample reported high levels of violence among their families of origin and low conflict resolution skills.