Behavioural food anticipation in clock genes deficient mice: confirming old phenotypes, describing new phenotypes

Animals fed daily at the same time exhibit circadian food-anticipatory activity (FAA), which has been suggested to be driven by one or several food-entrainable oscillators (FEOs). FAA is altered in mice lacking some circadian genes essential for timekeeping in the main suprachiasmatic clock (SCN). Here, we confirmed that single mutations of clock genes Per1(-/-) and Per2(Brdm1) alter FAA expression in constant darkness (DD) or under a light-dark cycle (LD). Furthermore, we found that Per1(-/-);Per2(Brdm1) and Per2(Brdm1);Cry1(-/-) double mutant animals did not display a stable and significant FAA either in DD or LD. Interestingly, rescued behavioural rhythms in Per2(Brdm1);Cry2(-/-) mice in DD were totally entrained to feeding time and re-synchronized after phase-shifts of mealtime, indicating a higher SCN sensitivity to feeding cues. However, under an LD cycle and restricted feeding at midday, FAA in double Per2(Brdm1);Cry2(-/-) mutant mice was absent. These results indicate that shutting down one or two clock genes results in altered circadian meal anticipation. Moreover, we show that in a genetically rescued SCN clock (Per2(Brdm1);Cry2(-/-)), food is a powerful zeitgeber to entrain behavioural rhythms, leading the SCN to be more sensitive to feeding cues than in wild-type littermates.

Stroke-like episodes in propionic acidemia caused by central focal metabolic decompensation

Propionic acidemia caused by propionyl-CoA carboxylase deficiency frequently leads to neurologic complications. Herein we report an eleven-year-old patient with propionic acidemia having three stroke-like episodes during a period of 13 months characterized by acute reversible hemiplegia and vegetative symptoms like bradycardia or drowsiness. No biochemical signs of severe metabolic decompensation were detectable in plasma. At all three episodes, EEG was not indicative for status epilepticus, but in the acute episode it showed slowing of background activity emphasized on one side. MRI revealed reversible hyperintensities in cortical grey matter and basal ganglia. During the third episode a lumbar puncture was done in parallel with venous puncture. Concentrations of glutamine (902 micromol/L), glycine (24 micromol/L) and alanine (78 micromol/L) were elevated in CSF. In plasma glycine (1 859 micromol/L) and alanine (608 micromol/L) concentrations were also elevated, whereas the glutamine (458 micromol/L) concentration was normal. CSF/plasma ratios were elevated for glutamine (1.97) and alanine (0.13) and normal for glycine (0.01). We assume that the stroke-like episodes in our patient may be caused by an acute focal cerebral metabolic decompensation, which is detectable by unspecific changes in MRI and by measuring amino acids and lactate in CSF versus plasma.

Quantitative detection of Clostridium difficile in hospital environmental samples by real-time polymerase chain reaction

C. difficile-associated diarrhoea occurs commonly in hospitals and is a significant cause of morbidity and mortality. Hospital surfaces are often contaminated with nosocomial pathogens and may be responsible for cross-transmission, especially if hardy Gram-positive and spore-forming organisms are involved. The aim of this study was to quantify C. difficile in the hospital environment near C. difficile-positive and -negative patients using a quantitative real-time polymerase chain reaction. A total of 531 samples was collected from the clinical environment and classified into three groups according to patient and ward status for C. difficile. As expected, there were significantly higher counts of C. difficile on the floor and in the near environment of C. difficile patients. However, a significant correlation was found between C. difficile counts on the floor and on the hands of patients and healthcare workers (HCWs) in wards without evidence of C. difficile. This suggests that asymptomatic carriage among patients and HCWs can also contribute towards C. difficile transmission in hospitals. In conclusion, C. difficile can be transmitted via personal contact or via contaminated areas of the hospital environment.

The multiple facets of Per2

The Period 2 (Per2) gene is an important component of the circadian system. It appears to be not only part of the core oscillator mechanism, but also part of the input and output pathways of the clock. Because of its involvement at multiple levels of the circadian system, Per2 needs to meet a variety of different demands. We discuss how Per2 might be able to fulfill multiple functions by reviewing known facts and combine this with speculations based on these facts. This might provide new views about Per2 function and help to better understand diseases that are rooted in the circadian system.

Activation of NF-κB by IL-1β blocks IL-6-induced sustained STAT3 activation and STAT3-dependent gene expression of the human γ-fibrinogen gene

Despite the essential role of the fibrinogen gamma-chain as a blood clotting factor, the fibrinogen gamma-chain contains a number of interaction sites to recruit other factors such as leukocytes important for prevention of pathogen entry and propagation of the repair process. Interleukin-6 (IL-6) is known as the major inducer of gamma-fibrinogen synthesis in hepatocytes, whereas IL-1beta has been shown to act as a potent inhibitor of gamma-fibrinogen expression. Studies on the rat fibrinogen gamma-chain promoter suggest that nuclear factor (NF)-kappaB replaces the signal transducer and activator of transcription (STAT) 3 from binding to overlapping NF-kappaB/STAT3 binding sites within the 5' regulatory region of the rat gamma-chain gene promoter. However, despite its physiological relevance, the underlying mechanism responsible for the inhibitory effect of IL-1beta in humans is still not understood and apparently more complex. In contrast to the mechanism described for the rat gene our results indicate that IL-1beta suppresses the IL-6-induced activation of the human gamma-fibrinogen gene particularly by blocking the late phase STAT3-tyrosine phosphorylation NF-kappaB-dependently but independent from de novo protein synthesis. Consequently, blocking NF-kappaB activation restores specifically late phase STAT3 activation as well as the induction of the human gamma-fibrinogen gene. In contrast, specifically early STAT3 activation could be restored by a block of the p38 mitogen-activated protein kinase (p38(MAPK)) pathway. In summary, our results indicate that expression of the gamma-fibrinogen gene is mainly controlled by the strength of late phase STAT3 activation, which in turn is negatively regulated by the extent of IL-1beta-mediated NF-kappaB activity.

Verhaltenssucht

Until recently knowledge was limited with respect to clinically relevant excessive reward-seeking behaviour such as pathological gambling, excessive shopping, and excessive working which meet diagnostic criteria of dependent behaviour. To date there is no consistent concept for diagnosis or treatment of excessive reward-seeking behaviour, and its classification is uncertain. However, the high number of subjects seeking treatment emphasises the importance of a clear conceptualisation of the so-called behavioural addictions and their successful treatment. Excessive reward-seeking behaviour may be used to regulate negative emotions. We suggest that, comparable to drug addiction, excessive reward-seeking behaviour can alleviate negative mood states and may be used as an (inadequate) stress coping strategy at the expense of active coping strategies. In the course of a pathological development, behavioural addiction may become the only available behavioural resource to cope with challenging developmental steps or social stress factors such as loneliness or anxiety.

[Interactions between clock gene mutation, circadian phenotype and tumor growth in mice]

The relation between circadian physiology (rest-activity and body temperature) and the growth of a grafted tumor (Glasgow osteosarcoma-GOS) was investigated in the mice with mutation of clock gene (ClockDelta19(-)) or gene controlled by the clock (Vpac(-/-)). Circadian rhythms in temperature and activity were stable, with an approximately 24-h period in all the mice synchronized by the alternation of 12 h of light and 12 h of darkness (LD 12:12). Following exposure to constant darkness (DD), both rhythms persisted in ClockDelta19(-), yet with a lengthening of the period by 4.5 h compared to wild type. In DD, the amplitude increased by 45.9% for the temperature rhythm (p<0.001) and by 17.4% for the activity one (p=0.08) as compared to LD 12:12 in ClockDelta19(-). The improvement of circadian coordination and/or the lengthening of the circadian period observed in ClockDelta19(-) kept in DD was associated with a moderate slowing down of tumor growth. Although the exposure to DD ablated the activity and temperature rhythms in Vpac(-/-), no modification in tumor growth was observed as compared to wide type or Vpac(-/-) in LD 12:12. Major alternations of circadian physiology can result from interactions between photoperiodic environment and mutation of clock gene or gene controlled by the clock. In these conditions, we have shown that the alternation of the circadian phenotype does not seem to constitute an essential determinant of the growth of a grafted tumor.

Osmotic regulation of STAT3 stability in H4IIE rat hepatoma cells

Little is known about the regulation of signal transducer and activator of transcription (STAT) stability. Here the osmolarity-dependence of STAT3 stability, ubiquitination, Tyr(705) phosphorylation, STAT3 transactivation and gamma-fibrinogen (gamma-FBG) expression was studied in hepatoma cells. Hyper-osmolarity accelerated STAT3 degradation which was prevented by proteasome inhibitors. Hypo-osmolarity stabilized STAT3, most likely due to a decrease in STAT3 ubiquitination. Accordingly, STAT3 Tyr(705) phosphorylation, alpha(2)-macroglobulin promoter activity and gamma-FBG expression were osmosensitive. Modulation of STAT3 stability may contribute to a hydration dependence of acute phase protein expression.

[Pathological gambling. An empirical study of the desire for addictive substances]

Drug craving, the irresistible urge for drug intake, is being discussed as a central construct for the explanation of addictive behaviour and for relapses so far only in substance-related addiction. Based on learning models for the maintenance of addiction, in this study, cue-induced craving and psychological variables that influence craving were investigated in subjects with excessive rewarding behaviour such as pathological gambling. Based on the cue-reactivity paradigm, pathological gamblers and healthy controls were exposed to gambling and other cues. Emotional processing of the gambling cues, cue-induced craving, and the influence on craving of depression, anxiety, and stress-coping strategies were investigated. The results demonstrate disorder-specific processing of cues in pathological gamblers, even after abstinence for more than a year. In addition, craving is influenced by psychological disabilities. Data are discussed with respect to comparable data in studies about substance-related addicts.

mPer1 and mPer2 mutant mice show regular spatial and contextual learning in standardized tests for hippocampus-dependent learning

Learning and memory, like most physiological processes, seem to be under the control of circadian rhythm. The recently cloned mPer1 and mPer2 genes play an important role in the regulation of the circadian rhythm. In this study, we tested mPer1 and mPer2 mutant mice in two different learning and memory paradigms, a water-maze place navigation task and contextual fear conditioning. In both learning tests, the hippocampus is critically involved. None of these learning types were affected by the mutations, suggesting that mPer1 and mPer2 do not play a major role in the regulation of hippocampus-dependent learning and memory.

Differential Effects of Vasodilatory Prostaglandins on Focal Adhesions, Cytoskeletal Architecture, and Migration in Human Aortic Smooth Muscle Cells

OBJECTIVE

Cyclooxygenases 1 and 2 are expressed in atherosclerotic arteries, and local generation of prostacyclin and prostaglandin E2 (PGE2) occurs. However, the role of cyclooxygenases and individual prostaglandins during plaque progression is currently uncertain. The present study characterizes the effect of vasodilatory prostaglandins on morphology, focal adhesion (FA) function, and migration in human aortic smooth muscle cells (SMCs).

METHODS AND RESULTS

The stable prostacyclin analog iloprost transiently induced: (1) disassembly of FA and stress fibers, (2) partial retraction and rounding of SMCs, (3) hypophosphorylation of FA kinase (FAK) and paxillin, and (4) inhibition of platelet-derived growth factor-BB-induced migration. Inhibition of FAK phosphorylation and morphological changes were mimicked by forskolin, inhibited by H89, and prevented by the protein tyrosine phosphatase inhibitor vanadate and by calpeptin. PGE2 was by far less efficient with respect to all parameters investigated. This difference correlated with the respective cAMP induction in response to iloprost and PGE2.

CONCLUSIONS

Inhibition of FAK phosphorylation and FA function is a new target of vasodilatory prostaglandins, which might be causally involved in the antimigratory effects of prostaglandins. Importantly, prostacyclin analogs and PGE2 differ dramatically with respect to dephosphorylation of FAK and inhibition of migration, which might be of relevance for their respective functions in atherosclerosis.

Dual Function of Interleukin-1β for the Regulation of Interleukin-6-induced Suppressor of Cytokine Signaling 3 Expression

Interleukin-6 (IL-6) exerts pro- as well as anti-inflammatory activities in response to infection, injury, or other stimuli that affect the homeostasis of the organism. IL-6-induced expression of acute-phase protein genes in the liver is tightly regulated through both IL-6-induced feedback inhibitors and the activity of pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-1beta. In previous studies mechanisms for how IL-1beta counteracts IL-6-dependent acute-phase protein gene induction have been proposed. Herein we analyzed IL-1beta-mediated regulation of IL-6-induced expression of the feedback inhibitor SOCS3. In hepatocytes IL-1beta alone does not induce SOCS3 expression, but it counteracts SOCS3-promoter activation in long term studies. Surprisingly, short term stimulation revealed IL-1beta to be a potent enhancer of SOCS3 expression in concert with IL-6. This activity of IL-1beta does not depend on IL-1beta-dependent STAT1-serine phosphorylation but on NF-kappaB-dependent gene induction. Such a regulatory network allows IL-1beta to counteract IL-6-dependent expression of acute-phase protein genes without inhibiting IL-6-induced SOCS3 expression and provides a reasonable mechanism for the IL-1beta-dependent inhibition of acute-phase gene induction, because reduced SOCS3 expression would lead to enhanced IL-6 activity.

The circadian clock: a manager of biochemical processes within the organism

The periodic succession of night and day has influenced life on earth for millions of years. Many organisms have "internalized" this periodic change in the form of the circadian clock. Its main function is to organize the time course of biochemical, physiological and behavioural processes thereby optimizing an organism's performance in anticipating changing environmental conditions. Therefore, it is important to understand the underlying mechanisms that connect the core pacemaker, which is located in the suprachiasmatic nuclei (SCN) of the hypothalamus, with peripheral organs. Several laboratories set out to identify genes that are under the influence of the circadian clock. It appears that the circadian clock coordinates transcription of key metabolic pathways thereby orchestrating the time course of physiological and behavioural processes. We review these investigations and put our experiments, the comparison of gene expression in SCN tissue of Per2 mutant and wild-type mice, in the context of these findings.

A randomized, blinded, prospective trial to compare the safety and efficacy of three bowel-cleansing solutions for colonoscopy (HSG-01*)

BACKGROUND AND STUDY AIMS

There are conflicting data regarding the optimal bowel preparation for colonoscopy. This study was carried out to compare the efficacy, safety, and tolerability of three widely used bowel lavage solutions: the standard polyethylene glycol-electrolyte solution based on the GoLytely formulation (PEG-EL1; Klean-Prep); a sulphate-free PEG-EL solution based on the NuLytely formulation (PEG-EL2, Endofalk); and a sodium phosphate preparation (NaP, Fleet Phospho-Soda).

PATIENT AND METHODS

A total of 185 consecutive patients scheduled for elective colonoscopy were prospectively randomly assigned to undergo pre-colonoscopic bowel cleansing with either 4 l of PEG-EL1 (n=64), 3 l of PEG-EL2 (n=59), or 90 ml of NaP (n=62). The quality of preparatory colonic cleansing for each segment from the rectum to the ascending colon was scored on a five-level rating scale (1, very good to 5, very poor) by endoscopists who were blinded with regard to the type of preparation used. The primary outcome measure for the comparison of treatments was the "worst" score in any of the rated bowel segments. Safety and tolerability were evaluated by means of a symptom questionnaire completed by each patient immediately before the procedure.

RESULTS

Of the 185 patients who were randomly assigned to one of the three treatments, 175 underwent colonoscopy and 173 were evaluable with regard to efficacy - 59, 54, and 60 patients treated with PEG-EL1, PEG-EL2, and NaP, respectively. The treatment groups were comparable with regard to the baseline characteristics. PEG-EL1 was statistically significantly superior to the other treatments in relation to the "worst cleansing" score ( P</=0.003). In addition, colonoscopic visualization was markedly better in each of the five bowel segments and general "very good" or "good" ratings were achieved in more than 90 % of patients treated with PEG-EL1. The percentages were consistently lower in the other two groups, particularly in the ascending colon. With the exception of the sigmoid, the differences in all segments of the large bowel were statistically significant (P</=0.04). Patient satisfaction was comparable between the treatment groups. Adverse events (mainly nausea/vomiting and abdominal pain) and deviations in laboratory values occurred more frequently in the NaP group.

CONCLUSIONS

Preparatory PEG-EL1 (Klean-Prep) was significantly superior to PEG-EL2 (Endofalk) and NaP (Fleet Phospho-Soda) in achieving effective cleansing of the entire colon prior to colonoscopy. On the basis of these data, PEG-EL1 can be regarded as the "gold standard" for bowel cleansing prior to colonoscopy.

IFN-alpha antagonistic activity of HCV core protein involves induction of suppressor of cytokine signaling-3

Eighty percent of patients newly infected with the hepatitis C virus (HCV) develop chronic infection, suggesting that HCV can develop effective strategies to escape the unspecific and specific immune response of the host. Because SOCS molecules have been recognized to be powerful inhibitors of cytokine signaling via the Jak/STAT pathway, virus-induced expression of these molecules should be an efficient instrument to counteract the cellular response toward interferons (IFNs), an essential part of first line antiviral immune response. This study shows that overexpression of HCV core protein inhibits IFN-alpha-induced tyrosine phosphorylation and activation of STAT1 in hepatic cells. With the use of a STAT1-YFP fusion protein, further evidence is given that HCV core is capable to inhibit nuclear translocation of STAT1. Inhibition of STAT1-tyrosine phosphorylation was accompanied by the induction of SOCS3-mRNA expression, suggesting that the HCV core protein impairs IFN-alpha-induced signal transduction via induction of SOCS3 expression. HCV core protein was competent to partially rescue growth of a genetically engineered influenza A virus lacking its own IFN antagonist. These IFN-antagonistic properties of the HCV core protein may be part of the molecular basis of IFN-alpha unresponsiveness in about one-half of chronically infected HCV-patients.

Multitrophic interactions of the silverleaf whitefly, host plants, competing herbivores, and phytopathogens

Our laboratory found that silverleaf whitefly (SLW; Bemisia argentifolii Bellows & Perring) feeding alters host plant physiology and chemistry. The SLW induces a number of host plant defenses, including pathogenesis-related (PR) protein accumulation (e.g., chitinases, beta-1,3-glucanases, peroxidases, chitosanases, etc.). Induction of the PR proteins by SLW feeding occurs in various plant species and varieties. The extent and type of induction is dependent on a number of factors that include host plant growing conditions, the length of time the host plant is exposed to SLW feeding, the plant variety, and SLW population densities. The appearance of PR proteins correlates well with reduced infestations of conspecific insect herbivore competitors. Greenhouse and field experiments in which herbivore competitors (cabbage looper, Trichoplusia ni; leaf miner, Liromyza trifolii) were placed on plants previously exposed to SLW feeding demonstrated behavioral differences (oviposition, feeding preferences) and reduced survival rates and development times of these insects. The interaction was asymmetrical, i.e., SLW infestations of plants previously exposed to leaf miners had little or no effect on SLW behavior (oviposition). Induction of plant-defensive proteins by SLW feeding was both local (at the feeding site) and systemic (uninfested leaves distant to the feeding site). There are interactions between diseases such as tomato mottle virus (ToMoV; a geminivirus) and the host plant and SLW. PR proteins were induced in tomato plants infected with ToMoV much as they were via non-viruliferous SLW feeding. The presence of ToMoV in tomato plants significantly increased the number of eggs produced by SLW females. Experiments using tomato plants, powdery mildew (PM), and tobacco mosaic virus (TMV) show that whitefly infestations can affect plant pathogen relationships but the effects vary among pathogen types. Enzyme analyses prior to pathogen inoculation showed that whitefly treatment significantly increased the activities of foliar chitinase and peroxidase. Evaluation of pathogen growth 3 weeks after inoculation showed that whitefly feeding significantly reduced the incidence of PM. However, TMV levels evaluated by ELISA were not significantly affected by whitefly feeding. Six weeks after inoculation with pathogens, the chitinase and peroxidase activities were still elevated in plants initially fed on by whiteflies but continuing pathogen infection had no effect on these enzymes. The possibility that geminivirus infection and/or SLW infestations isolate the host plant for the selected reproduction of the virus and the insect is discussed. Multitrophic cascade effects may contribute to the successful eruptive appearance of SLW on various crops, ranking them as a major pest. They may explain the general observation that when SLW infest a host plant there are few if any competing insect herbivores and pathogens found in the host. However, the results indicate that certain SLW-virus relationships could be mutualistic.

Biological clock in total darkness: the Clock/MOP3 circadian system of the blind subterranean mole rat

Blind subterranean mole rats retain a degenerated, subcutaneous, visually blind but functionally circadian eye involved in photoperiodic perception. Here we describe the cloning, sequence, and expression of the circadian Clock and MOP3 cDNAs of the Spalax ehrenbergi superspecies in Israel. Both genes are relatively conserved, although characterized by a significant number of amino acid substitutions. The glutamine-rich area of Clock, which is assumed to function in circadian rhythmicity, is expanded in Spalax compared with that of humans and mice, and is different in amino acid composition from that of rats. We also show that MOP3 is a bona fide partner of Spalax Clock and that the Spalax Clock/MOP3 dimer is less potent than its human counterpart in driving transcription. We suggest that this reduction in transcriptional activity may be attributed to the Spalax Clock glutamine-rich domain, which is unique in its amino acid composition compared with other studied mammalian species. Understanding Clock/MOP3 function could highlight circadian mechanisms in blind mammals and their unique pattern as a result of adapting to life underground.

The circadian clock and behavior

Temporal organization is a fundamental feature of all living systems. Timing is essential for development, growth and differentiation and in the mature organism, it is essential to maintain normal physiology and behavior. The biological entity that permits an organism's day/night organization is the circadian system. In the following, we describe how daily or circadian activity is measured in mice, and what such activity measurements can tell us about the state of the animal.

Circadian rhythms: a fine c(l)ocktail!

The central pacemaker of circadian behavior in mammals is located in the suprachiasmatic nuclei, each neuron of which has its own circadian rhythm. Recent studies shed light on the integration of these individual cellular rhythms and on novel genetic determinants that have been found to influence circadian behavior.

Inversion of the circadian rhythm of melatonin in the Smith-Magenis syndrome

OBJECTIVE

The objective was to determine the circadian rhythm of melatonin in the Smith-Magenis syndrome (SMS), which causes behavioral problems and sleep disturbance.

STUDY DESIGN

Questionnaires, sleep consultations, and sleep diaries were obtained in 20 children with SMS (9 girls, 11 boys aged 4 to 17 years). Actigraphy, electroencephalography, and the circadian variations of plasma melatonin, cortisol, and growth hormone were recorded in 8 patients. Early sleep onset, early sleep offset, and sleep attack indicated sleep disturbance.

RESULTS

All children with SMS had a phase shift of their circadian rhythm of melatonin. Time at onset of melatonin secretion was 6 AM +/- 2 (control group: 9 P.M. +/- 2). Peak time was 12 PM +/- 1 (control group: 3:30 AM +/- 1:30), and melatonin offset was at 8 PM +/- 1 (control group: 6 AM +/- 1). Behavioral problems correlated with the inverted circadian rhythm of melatonin.

CONCLUSION

Considering that clock genes mediate the generation of circadian rhythms, we suggest that haploinsufficiency for a circadian system gene mapping to chromosome 17p11.2 may cause the inversion of the circadian rhythm of melatonin in SMS.

Nonredundant roles of the mPer1 and mPer2 genes in the mammalian circadian clock

Mice carrying a null mutation in the Period 1 (mPer1) gene were generated using embryonic stem cell technology. Homozygous mPer1 mutants display a shorter circadian period with reduced precision and stability. Mice deficient in both mPer1 and mPer2 do not express circadian rhythms. While mPER2 regulates clock gene expression at the transcriptional level, mPER1 is dispensable for the rhythmic RNA expression of mPer1 and mPer2 and may instead regulate mPER2 at a posttranscriptional level. Studies of clock-controlled genes (CCGs) reveal a complex pattern of regulation by mPER1 and mPER2, suggesting independent controls by the two proteins over some output pathways. Genes encoding key enzymes in heme biosynthesis are under circadian control and are regulated by mPER1 and mPER2. Together, our studies show that mPER1 and mPER2 have distinct and complementary roles in the mouse clock mechanism.

Rhogocytes (pore cells) as the site of hemocyanin biosynthesis in the marine gastropod Haliotis tuberculata

Rhogocytes (pore cells) are specific molluscan cell types that are scattered throughout the connective tissues of diverse body parts. We have identified rhogocytes in large numbers in tissue taken from mantle, foot and midgut gland of the abalone Haliotis tuberculata (Vetigastropoda). Within cisternae of the endoplasmic reticulum, particles are visible that resemble, in shape and size, hemocyanin molecules, the respiratory protein of many molluscs. Immunohistochemical experiments using hemocyanin-specific antibodies demonstrated that these cells contain hemocyanin. In situ hybridization with a cDNA probe specific for Haliotis hemocyanin showed that hemocyanin-specific mRNA is present in rhogocytes, which confirmed that they are the site of hemocyanin biosynthesis in this gastropod. A possible path of hemocyanin release into the hemolymph is discussed. Also in the vetigastropod Megathura crenulata, many rhogocytes could be detected. However, they lacked hemocyanin molecules which, together with published data, indicates a seasonal expression of hemocyanin in this animal.

Initial demonstration of rhythmic Per gene expression in the hypothalamus of a non-mammalian vertebrate, the house sparrow

In mammals, the major pacemaker controlling circadian rhythmicity is located in the hypothalamic suprachiasmatic nuclei which are characterized by specific molecular features including the expression of three homologues of the Drosophila clock gene period (per). Until now, no comparable structure has been unambiguously described in the brain of any non-mammalian vertebrate. We cloned the PAS-domain of the Per2 gene in the house sparrow (Passer domesticus), a model organism in circadian research. Hypothalamic expression of passerPer2 (pPer2) showed a marked diurnal rhythm in the suprachiasmatic nucleus, a cell group located in the anterior hypothalamus directly above the optic chiasm and adjacent to the third ventricle. Additionally, pPer2 was diurnally expressed in the lateral hypothalamus. This first demonstration of rhythmic clock gene expression in the hypothalamus of a non-mammalian vertebrate provides basic information for future research on the evolution of circadian pacemaking systems.