Rapid Darkening Research Articles

Establishing Age-Based Color Changes for the American Burying Beetle, Nicrophorus americanus Olivier, with Implications for Conservation Efforts.

The American burying beetle, Nicrophorus americanus Olivier, is a federally protected insect that once occupied most of eastern North America. Adult beetles feature distinct, recognizable markings on the pronotum and elytra, and color changes with age have been observed. Among the challenges faced by research scientists and conservation practitioners is the ability to determine beetle age in the field between and including teneral (young) and senescent (old) adult stages. Using 20 (10 male and 10 female) captive-bred beetles, we characterized the change in greyscale and red, green, and blue (RGB) color channels over the lifespan of each beetle for field-aging applications. Individual beetles were photographed at set intervals from eclosion to death, and color data were extracted using open-source ImageJ Version 1.54f software. A series of linear mixed-effects models determined that red color showed the steepest decrease among all color channels in the pronotum and elytral markings, with a more significant decrease in the pronotum. The change in greyscale between the pronotum and elytral markings was visibly different, with more rapid darkening in the pronotum. The resulting pronotum color chart was tested under field conditions in Oklahoma, aging 299 adult N. americanus, and six age categories (day range) were discernable by eye: teneral (0-15), late teneral (15-31), early mature (31-45), mature (45-59), early senescent (59-76), and senescent (76-90). The ability to more precisely estimate age will improve population structure estimates, laboratory breeding programs, and potential reintroduction efforts.

Discovery of a new highly pathogenic toxin involved in insect sepsis.

Insect sepsis is a severe consequence that arises from the invasion of the hemocoel by symbionts of entomopathogenic nematodes and bacteria. In the present study, we unveiled the heightened virulence of the entomopathogenic nematode Steinernema feltiae and the entomopathogenic bacteria Xenorhabdus bovienii, which operate symbiotically, against the wax moth Galleria mellonella. Maximum mortality was observed at 25°C while the optimal infestation efficiency was 20 nematodes per host. After infestation, G. mellonella displayed rapid darkening and softening, accompanied by an escalated esterase activity at 9 h. The X. bovienii, released by S. feltiae, underwent substantial proliferation and discharged toxins that attacked hemocytes, thus triggering extensive hemolysis and sepsis. The host G. mellonella was usually killed within 24 h due to disseminated septicemia. Additionally, X. bovienii infestation led to the upregulation of metabolites like 3-hydroxyanthranilic acid. Strikingly, we identified the perilous actinomycin D, generated through kynurenine metabolites, representing a novel biomarker of insect sepsis. Furthermore, a comprehensive transcriptomic analysis unveiled a noteworthy upregulation of gene expression associated with actinomycin D. Overall, X. bovienii induced apoptosis and sepsis through actinomycin D production, indicating its pivotal role in infestation activity. These findings open up new avenues for studying the mechanism of sepsis and developing innovative biotic pesticides. IMPORTANCE As a current biocontrol resource, entomopathogenic nematodes and their symbiotic bacterium can produce many toxin factors to trigger insect sepsis, having the potential to promote sustainable pest management. In this study, we found Steinernema feltiae and Xenorhabdus bovienii were highly virulent against the insects. After infective juvenile injection, Galleria mellonella quickly turned black and softened with increasing esterase activity. Simultaneously, X. bovienii attacked hemocytes and released toxic components, resulting in extensive hemolysis and sepsis. Then, we applied high-resolution mass spectrometry-based metabolomics and found multiple substances were upregulated in the host hemolymph. We found extremely hazardous actinomycin D produced via 3-hydroxyanthranilic acid metabolites. Moreover, a combined transcriptomic analysis revealed that gene expression of proteins associated with actinomycin D was upregulated. Our research revealed actinomycin D might be responsible for the infestation activity of X. bovienii, indicating a new direction for exploring the sepsis mechanism and developing novel biotic pesticides.

Organization and dynamics of the SpoVAEa protein and its surrounding inner membrane lipids, upon germination of Bacillus subtilis spores

The SpoVA proteins make up a channel in the inner membrane (IM) of Bacillus subtilis spores. This channel responds to signals from activated germinant receptors (GRs), and allows release of Ca2+-DPA from the spore core during germination. In the current work, we studied the location and dynamics of SpoVAEa in dormant spores. Notably, the SpoVAEa-SGFP2 proteins were present in a single spot in spores, similar to the IM complex formed by all GRs termed the germinosome. However, while the GRs’ spot remains in one location, the SpoVAEa-SGFP2 spot in the IM moved randomly with high frequency. It seems possible that this movement may be a means of communicating germination signals from the germinosome to the IM SpoVA channel, thus stimulating CaDPA release in germination. The dynamics of the SpoVAEa-SGFP2 and its surrounding IM region as stained by fluorescent dyes were also tracked during spore germination, as the dormant spore IM appeared to have an immobile germination related functional microdomain. This microdomain disappeared around the time of appearance of a germinated spore, and the loss of fluorescence of the IM with fluorescent dyes, as well as the appearance of peak SpoVAEa-SGFP2 fluorescent intensity occurred in parallel. These observed events were highly related to spores’ rapid phase darkening, which is considered as due to rapid Ca2+DPA release. We also tested the response of SpoVAEa and the IM to thermal treatments at 40–80 °C. Heat treatment triggered an increase of green autofluorescence, which is speculated to be due to coat protein denaturation, and 80 °C treatments induce the appearance of phase-grey-like spores. These spores presumably have a similar intracellular physical state as the phase grey spores detected in the germination but lack the functional proteins for further germination events.

Use of topinambur in technology of flour products

The article considers the use of Jerusalem artichoke processing products in technology flour yeast products. In terms of productivity, Jerusalem artichokes significantly exceed potatoes, sugar beets, corn and other crops of intensive type, but grow it on small area mainly for fodder purposes. Recently, in the food industry is observed reorientation to the production of products with new qualities, aimed at improving the situation health and disease prevention. Jerusalem artichoke is a unique raw material that can increase the biological value of finished products. Useful properties of Jerusalem artichoke are used to strengthen the immune system, reduce the risk of heart attack and stroke, eliminate salt deposits in the joints, in the therapeutic diet for diabetes. However, its limited use in the processing industry is due to the rapid enzymatic darkening of Jerusalem artichoke tubers during processing. Given the specific properties of Jerusalem artichoke, it is advisable to investigate the enzymatic darkening of Jerusalem artichoke tubers during processing by determining the activity of the enzyme polyphenol oxidase and the use of Jerusalem artichoke puree in the technology of yeast dough. Analysis of tubers and Jerusalem artichoke puree was performed by organoleptic and physicochemical indicators. The quality of finished products was controlled by organoleptic, physicochemical and structural and mechanical indicators, among which special attention was paid to indicators acidity, humidity, porosity, shape stability. The activity of the enzyme in whole and crushed Jerusalem artichoke tubers and its effect on the activity of the enzyme pre-blanching in water for 10 minutes It is determined that when blanching is a partial inactivation of the enzyme polyphenol oxidase, which prevents darkening of raw materials during grinding. The effect of adding Jerusalem artichoke puree in the amount of 10, 15 and 20 % was studied on gluten of wheat flour. The partial replacement of wheat flour in mashed Jerusalem artichoke leads not only to a decrease in the amount of gluten, but also to a change in its quality. The gluten becomes more elastic, the extensibility decreases, and with the addition of 20 % puree gluten is torn. It is determined that the duration of fermentation of dough samples varies depending on the amount introduced Jerusalem artichoke puree. With increasing percentage of Jerusalem artichoke puree in the dough recipe, the duration of dough fermentation is reduced by 6.25…8.75 %. The addition of puree had a positive effect Jerusalem artichoke to increase the yield of the finished product by 5.20…26.34 %. Research of the main quality indicators of experimental samples confirm that according to the set of indicators, the optimal sample is 10 % of Jerusalem artichoke puree, which makes it possible to recommend it for the production of yeast bakery products of high biological value.

Aging indicators for stored carioca beans

High temperature, moisture content and radiation conditions, common in the tropics, accelerate the physiological post-harvest disorders in beans, affect integument color and bean hardness. This study explored the darkening and hardening mechanisms in carioca type beans during storage. The contrasting genotypes for bean darkening and hardening (BRS Estilo and BRS Pontal: rapid darkening and hardening; BRSMG Madrepérola and CNFC 10467: slow darkening and partially resistant to hardening; and a Canadian genotype of the Pinto Bean type resistant to darkening (negative control)) were evaluated right after harvest and after six months storage at 20.3 ± 0.2 °C and 78.9 ± 6.0% RH, with respect to their physicochemical, biochemical and morphological attributes. All the samples hardened with time, but the velocity of darkening did not always parallel the degree of hardening of the beans (that increase linearly with time), which indicates that the color of the bean integument was not a safe indicator to predict the culinary quality of carioca beans. During storage, the SOD (superoxide dismutase) activity and LP (lipid peroxidation) in the cotyledon increased, and the increase was more significant in the integument of the rapid-darkening genotypes. The oxidative stress detected in the beans apparently started in the green bean formation phase, continuing during post-harvest, especially for the rapid-darkening beans. Quantification of the bivalent ions in the bean fractions, together with the degree of membrane damage was positively associated with bean darkening, independent of the group. Thus, aging of the carioca beans could be triggered by a complex mechanism involving diverse intrinsic factors in different degrees according to the genotype and the post-harvest period, but some parameters could serve as indicators, as cooking time, hardness and color, to differentiate between rapid and slow darkening beans.

Communist Proteins: Lenin's Skin, Astrobiology, and the Origin of Life

Communist ProteinsLenin's Skin, Astrobiology, and the Origin of Life Alexei Yurchak (bio) If every physical and chemical invention is a blasphemy, every biological invention is a perversion. —J. B. S. Haldane We might say indeed that modern man has an epidermis rather than a soul. —James Joyce Body without Organs When Lenin died on 21 January 1924, there were no plans to preserve his body, and the funeral was planned for 27 January. However, in part due to extremely cold temperatures that winter, the body showed no signs of decay for longer than usual.1 Every few days party commissions checked the condition [End Page 683] of the body, making sure that it remained in a good state, until in March warm weather brought the first alarming signs of decomposition.2 The unexpectedly long period during which Lenin's body remained un-buried allowed the party leaders to discuss its possible future in greater detail than they could have otherwise. At first, any mention of long-term preservation and display seemed controversial, and to some in the leadership sounded like a violation of their materialist worldview. But others insisted that it was important to display Lenin's body for a while longer, if not indefinitely, to let the proletarians of the world bid farewell to their leader.3 Eventually it was decided to allow Professor of Medicine Vladimir Vorob´ev and the biochemist Boris Zbarskii to try an experimental embalming method they proposed. They worked on the body for four months and in late July 1924 reported success. If Lenin's body were regularly reembalmed according to their method, they claimed, it was likely to remain in a good condition for a very long time.4 After that report, everything changed. Lenin's body was no longer a decomposing corpse, and talking about burying it seemed inappropriate. The transcripts of the debates among party leaders before the embalming suggest that they saw Lenin's body in two distinct ways: not only as the body of a flesh-and-blood individual called Lenin but also as the embodiment of the foundational truth of the communist project—truth that was different from Lenin and bigger than him. This doubled body stood for "Leninism"—both a man's teaching and a truth that far transcended that man.5 This perception affected how the body was eventually preserved and the procedures to which it has been subjected since. It is important to stress, however, that this project has never been linked to any hopes or plans for Lenin's literal resurrection. Sometimes journalistic and academic accounts suggest that Lenin's body may have been preserved because Bolsheviks believed that science would one day be able to revive the leader.6 At the time of Lenin's death, there were also popular rumors about supposed plans to do so. However, the scientists and [End Page 684] politicians who were involved in the project of preserving Lenin's body never discussed resurrection. And if we consider how Lenin's body was preserved, it appears that they never privately considered that idea either. For example, the original plans to freeze Lenin's body—a form of preservation that might seem reminiscent of contemporary cryonics and therefore might give at least some grounds to speculations about resurrection—were quickly abandoned for several reasons.7 It had become clear that freezing would preserve not only the body but also all its visible defects, while liquid embalming could allow the scientists to continue fixing these defects later.8 Also, an experiment in freezing a dead human body that was conducted soon after Lenin's death demonstrated that even small fluctuations in temperature led to rapid darkening of the body's tissues and decomposition. In a country devastated by the Civil War electrical grids were unstable, and freezing was ruled out as too risky. Most importantly, the dual way of thinking about Lenin's body translated into a particular understanding of what preservation might mean in his case. It was not Lenin's full physical body that was preserved but only part of its material structure—its skeleton, skin, muscle tissues, and outward form and appearance, but neither its...

Transcriptomics reveals the molecular processes of light-induced rapid darkening of the non-obligate cave dweller Oreolalax rhodostigmatus (Megophryidae, Anura) and their genetic basis of pigmentation strategy

BackgroundVertebrates use different pigmentation strategies to adapt to various environments. A large amount of research has been done on disclosing the mechanisms of pigmentation strategies in vertebrates either under light, or, living in constant darkness. However, less attention has been paid to non-obligate, darkness dwellers. Red-spotted toothed toads Oreolalax rhodostigmatus (Megophryidae; Anura) from the karst mountainous region of southwestern China are non-obligate cave dwellers. Most tadpoles of the species possess transparent skin as they inhabit the dark karst caves. But remarkably, the transparent tadpoles can darken just within 15 h once exposed to light. Obviously, it is very significant to reveal molecular mechanisms of the unexpected rapid-darkening phenomenon.ResultsWe compared the transcriptomes of O. rhodostigmatus tadpoles with different durations of light exposure to investigate the cellular processes and potential regulation signals for their light-induced rapid darkening. Genes involved in melanogenesis (i.e. TYR, TYRP1 and DCT) and melanocyte proliferation, as well as their transcriptional factor (MITF), showed light-induced transcription, suggesting a dominating role of morphological color change (MCC) in this process. Transcription of genes related to growth factor, MAPK and PI3K-Akt pathways increased with time of light exposure, suggesting that light could induce significant growth signal, which might facilitate the rapid skin darkening. Most importantly, an in-frame deletion of four residues was identified in O. rhodostigmatus melanocortin-1 receptor (MC1R), a critical receptor in MCC. This deletion results in a more negatively charged ligand pocket with three stereo-tandem aspartate residues. Such structural changes likely decrease the constitutive activity of MC1R, but increase its ligands-dependent activity, thus coordinating pigment regression and rapid melanogenesis in the dark and light, respectively.ConclusionOur study suggested that rapid MCC was responsible for the light-induced rapid darkening of O. rhodostigmatus tadpoles. Genetic mutations of MC1R in them could explain how these non-obligate cave dwellers coordinate pigment regression and robust melanogenesis in darkness and light, respectively. To our knowledge, this is the first study that reports the association between pigmentation phenotype adaptation and MC1R mutations in amphibians and/or in non-obligate cave dwellers.

A study of the light sensitivity of birch bark

ABSTRACTBirch bark is commonly found in indigenous collections in Canadian museums. It is empirically known that light can cause the cambium side of birch bark to change colour. The purpose of this research is to better assess the light sensitivities of various colours of birch barks, and the manner, degree, and rate of colour change during light exposure. Six barks with different colours were used: beige, yellow, orange, orange-brown, red, and brown. Samples were exposed to daylight through a north-facing window (window), LED light from an enclosed chamber (LED), and the Newport-Oriel microfade tester (MFT). Window and MFT samples received a total light dose of approximately 25 Mlux-hours, and LED samples, 182 Mlux-hours. Colour monitoring of the samples showed that almost all barks initially darkened and then faded. Daylight through window caused the most rapid and extensive darkening and fading. Bluewool (BW) ratings for window samples were the lowest (most light sensitive). The MFT and LED samples showed a similar degree of colour change, with the same dose, despite the difference in intensity. Ratings of MFT samples are within one BW step difference compared to LED samples. The rate and extent of initial darkening depended on the colour of the bark; the middle range orange-toned barks showed the most rapid and extensive darkening followed by fading.

Effect of anodic polarization on the free-floating parts at Pt/YSZ catalyst electrode

Photoemission electron microscopy (PEEM) was used as spatially resolving method to explore the effect of electrochemical pumping with a positive voltage to porous platinum electrodes interfaced as working electrode to yttrium stabilized zirconia (YSZ). The experiments were conducted under UHV conditions (p≈10−9mbar). In PEEM a uniform rapid darkening of the Pt surface was observed during anodic polarization followed by the appearance of bright spots on a dark background. The bright spots observed in PEEM images are due to zirconia reduction around electrically isolated Pt islands.

Thermochemistry of methoxythiophenes: Measurement of their enthalpies of vaporization and estimation of their enthalpies of formation in the condensed phase

Enthalpies of vaporization of 2- and 3-methoxythiophenes (48.32±0.30 and 48.54±0.22kJ·mol−1, respectively) have been measured by the transpiration method using nitrogen as the carrying and protecting stream. Combustion experiments leading to enthalpies of formation in the liquid phase, ΔfH0m(l), for both isomers failed due to rapid darkening of freshly distilled samples even under a protecting atmosphere. However, combination of experimental vaporization enthalpies with values of the gaseous enthalpies of formation, ΔfH0m(g), obtained by quantum-chemical calculations from our previous work Notario et al. (2012) [24] permits establishing estimated ΔfH0m(l) values of −(68.3±4.2) and −(80.1±4.2)kJ·mol−1, for 2- and 3-methoxythiophene, respectively.

In Vitro Infection of Pupae with Israeli Acute Paralysis Virus Suggests Disturbance of Transcriptional Homeostasis in Honey Bees (Apis mellifera)

The ongoing decline of honey bee health worldwide is a serious economic and ecological concern. One major contributor to the decline are pathogens, including several honey bee viruses. However, information is limited on the biology of bee viruses and molecular interactions with their hosts. An experimental protocol to test these systems was developed, using injections of Israeli Acute Paralysis Virus (IAPV) into honey bee pupae reared ex-situ under laboratory conditions. The infected pupae developed pronounced but variable patterns of disease. Symptoms varied from complete cessation of development with no visual evidence of disease to rapid darkening of a part or the entire body. Considerable differences in IAPV titer dynamics were observed, suggesting significant variation in resistance to IAPV among and possibly within honey bee colonies. Thus, selective breeding for virus resistance should be possible. Gene expression analyses of three separate experiments suggest IAPV disruption of transcriptional homeostasis of several fundamental cellular functions, including an up-regulation of the ribosomal biogenesis pathway. These results provide first insights into the mechanisms of IAPV pathogenicity. They mirror a transcriptional survey of honey bees afflicted with Colony Collapse Disorder and thus support the hypothesis that viruses play a critical role in declining honey bee health.

Improved reversibility of color changes in electrochromic Ni–Al layered double hydroxide films in presence of electroactive anions

The effect of four electroactive anions, [Fe(CN)6]4−, [Ru(CN)6]4−, [Mo(CN)8]4− and [IrCl6]2−, on the electrochromic properties of Ni–Al layered double hydroxide (LDH) films was investigated. The presence of these ions, either in solution or pre-adsorbed in the LDH was found to greatly improve the reversibility of the color changes observed upon oxidation–reduction of nickel in the LDH layers. For example, the relative transmittance of a LDH pre-exchanged with [Fe(CN)6]4− recorded in situ during a potential scan dropped to 67% on oxidation and returned to 99.9% on reduction. These color changes could be sustained over multiple potential scans. The contrast between the colored and bleached states (ΔOD) remained almost constant at 0.17 for at least forty scans. This improvement in the electrochromic response of the films is attributed to mediation of the redox process in the LDH by the anions that resulted in the full reduction of all nickel sites back to Ni(II). In the absence of mediator, the electrochemical reduction of nickel in LDH films is very slow. Oxidized nickel sites accumulated in the films and cause a rapid darkening. Electron transfer between electroactive anions in solutions or adsorbed in the films and the electrochemically oxidized nickel sites is supported by for the large enhancements of the peak for reduction of the anions observed in the CVs. It is also confirmed by iodometry measurements showing the electrochemical oxidation of the LDH nickel sites to be fully reversible in presence of the anions. This was not the case when the oxidation was done in blank borate buffer.

Bill coloration, a flexible signal in a tropical passerine bird, is regulated by social environment and androgens

Although some group-living animals dynamically modify sexual signals in response to changes in social or reproductive status, this ability is often limited by constraints inherent in the mechanism of signal production. In birds, for example, inflexible moult schedules may restrict the ability to rapidly modify plumage-based signals. In such cases, more flexible secondary signals such as skin, eye, or bill coloration (e.g. soft parts) could potentially be used to achieve dynamic signalling. We addressed the degree to which free-living red-backed fairy-wrens, Malurus melanocephalus, can dynamically update both plumage and soft part signals when status suddenly changes, and how this may be achieved. In this cooperatively breeding passerine, dominant breeding males are distinguished from socially subordinate nonbreeding auxiliary males by the presence of nuptial plumage, dark bills and large sperm storage organs. Following an experimentally induced shift in status from auxiliary to breeder, males showed rapid increases in excreted androgen metabolites. Although they showed no overall change in nuptial plumage colour, several experimental males developed red nuptial feathers on the back following feather plucking, indicating that they had the capacity to develop bright nuptial plumage but were constrained from doing so by the moult schedule. In contrast, experimental males showed a rapid darkening of their bills, reflecting their newly acquired breeding status. These findings (1) provide experimental evidence that status affects physiologically controlled visual signals in free-living birds, (2) suggest that this linkage is mediated by testosterone and (3) illustrate how secondary ornaments may be used in dynamic signalling when the primary signalling modality is constrained.

Flexibility in the colouration of the meninx (brain covering) in the guppy (Poecilia reticulata): investigations of potential function

Many organisms can change the apparent colour of their bodies by altering the aggregation of pigment in chromatophores in a process known as physiological colour change. In this study, we investigate a previously unstudied example of physiological colour change, from clear to black, of a brain covering, or meninx, in the guppy ( Poecilia reticulata Peters, 1859). UV protection in bright light was our primary hypothesis for the function of the meningeal colour, with a cost of increased conspicuousness to avian predators selecting for plasticity in the trait. An alternate hypothesis was that this flexible trait could be a physiological by-product of stress. Thus, we investigated the response of meningeal colour to light, stress, and simulated predator attacks, and also whether the black meninx affected conspicuousness to potential predators. Meningeal response to higher light levels did not differ from baseline responses. However, we did find that stress induced a sex-biased, rapid darkening of the meninx; this darkening then declined over time. These results suggest that meningeal blackness could be used as a novel, noninvasive indicator of stress level in guppies. We found no evidence for a role of predation in meningeal colour: meninx colour did not respond to the presence of a predator model and human “predators” detected similar numbers of guppies with black meninges and guppies with clear meninges.

Effect of the presence of [formula omitted] on the electrochromic responses of films of a redox active Ni–Al-layered double hydroxide

The addition of [ Co ( bpy ) 3 ] 2 + to the electrolyte was found to improve the reversibility of the colour change observed in films of a Ni–Al-LDH upon oxidation–reduction of nickel in the LDH layers. Sustained changes in relative transmittance between 95% in the reduced state and 75% in the oxidized state were obtained for a film subjected to continuous potential scanning in a pH 8 borate buffer containing 0.1 mM [ Co ( bpy ) 3 ] 2 + . This improvement in the electrochromic response of the film is attributed to mediation of the redox process in the LDH by the cobalt cations that resulted in the full reduction of all nickel sites back to Ni(II) by the end of each individual scan. In the absence of the cobalt cation, the colour changes were not fully reversible and a rapid darkening of the film was observed. Because the unaided electrochemical reduction of nickel in LDH films is very slow, oxidized nickel sites remained in the films at the end of each scan. This accumulation of Ni(III,IV) sites was confirmed by increases in the average nickel valence in the films determined by iodometry, and by the appearance of reflection due to a Ni(III) oxyhydroxide phase in the XRD pattern of the film. This was not found when the cycling was done in presence [ Co ( bpy ) 3 ] 2 + . Mediation of the reduction of nickel in the Ni–Al-LDH by the cobalt cation was very efficient. The presence of 5 μM [ Co ( bpy ) 3 ] 2 + was sufficient to cause a significant improvement of the bleaching process.

Changes in breeding status are associated with rapid bill darkening in male red-backed fairy-wrens Malurus melanocephalus

Changes in breeding status are associated with rapid bill darkening in male red-backed fairy-wrens Malurus melanocephalus

The high-temperature degradation of hydraulic oils and fluids©

The rapid darkening of hydraulic oils and fluids in use has occasionally been reported. This paper summarizes the past investigations into this phenomenon, which have largely focused on the compression of air bubbles in mineral hydraulic oil. The process leads to a form of high temperature degradation known as dieseling and the probable formation of sub-micron carbonaceous particles. The importance of system design and particularly the choice of pumps, in this process, are discussed. The primary objective, however, is to examine the effects of dieseling on phosphate ester fire-resistant fluids and to clarify if an analysis of the used fluid can indicate whether this process is taking place. An investigation of samples taken from systems displaying rapid degradation suggests that the presence of certain breakdown products may infer the approximate level of temperature to which, at least, small amounts of the fluid are being subjected. The presence of carbonaceous material in the dieseling process is also confirmed. Some suggestions made for the mechanism of its formation as well as the formation of other major degradation products. Lastly, recommendations are made for ways of minimizing this form of breakdown not only in terms of system design but also with respect to fluid properties, fluid maintenance and the use of in-situ conditioning. Copyright © 2006 John Wiley & Sons, Ltd.

Cuticular colour change after imaginal eclosion is time‐constrained: blacker beetles darken faster

Abstract Adult mealworm beetles, Tenebrio molitor L. (Coleoptera: Tenebrionidae), show density dependent polyphenism in adult cuticular colour that is correlated with prophylactic immunity (Barnes & Siva‐Jothy, 2000). The degree of cuticular colour is important in understanding the biology of a number of insect‐related phenomena (e.g. industrial melanism, thermoregulation). In this paper, the extent of variation in cuticular colour in a large outbred population is documented; the rate of darkening under three different rearing protocols including experimental selection for cuticular colour is examined; and the time taken for cuticular colouring to be completed is determined. The results show that cuticular colouring after eclosion is time‐constrained in T. molitor, regardless of whether beetles are reared in large outbred cultures, inbred cultures, or cultures subjected to selection for darkness or lightness. Blacker beetles always darkened faster. The potential reasons for the constraint and the potential costs of rapid darkening are discussed.

Photometric monitoring of three BL Lacertae objects in 1993-1998

The results of optical photometric (BV RI) monitoring of three BL Lac objects over a time interval of about four years are presented. The sources are three classical radio-selected BL Lac objects, BL Lac, OJ 287 and PKS 0735+178. During our observation OJ 287 was in the stage of a large periodic outburst which consisted of at least two peaks. Almost all the observations obtained over consecutive nights detected intranight variations. In 1995 and 1996 BL Lac kept in faint states, with fewer and smaller rapid flares and fluctuations. On the contrary, in late 1997 BL Lac was at the stage of a large outburst, accompanied with much more large amplitude rapid flares and fluctuations. PKS 0735+178 was almost at its faint end from 1994 to early 1998. Over this time interval, the intraday variations and microvariations in PKS 0735+178 were rare and the amplitude was very small, except a rapid darkening of similar to 0.4 mag on 24 January 1995. Previous work by Webb et al. (1988); Wagner et al. (1996); Plan et al. (1997) also showed the same behaviour of variability as BL Lac and PKS 0735+178 in BL Lac, S5 0716+714, PKS 2155 - 304, respectively. We propose that the motion of orientation of the relativistic jet in a BL Lac object be responsible for these variability behaviours.

A rapid tyrosinase test for detecting contamination of durum wheat

A tyrosinase test has been developed for detecting contamination of durum wheat by breadwheat (T. aestivum) cultivars. Soaking the wheat seeds in tyrosinate solution and exposure to air leads to rapid darkening of the grain from aestivum cultivars, which can then be distinguished readily from the durum wheat in 30 min or less. The substrate is non-toxic and safe to handle. The test will differentiate both hard and soft aestivum cultivars from durum, and is suitable for use in quality control at the point of intake.