Compound heterozygosity for TNXB genetic variants in a mixed‐breed dog with Ehlers‐Danlos syndrome

The Ehlers‐Danlos syndromes (EDSs) are a heterogeneous group of inherited connective tissue disorders characterized by skin hyperextensibility, joint hypermobility and tissue fragility. Inherited disorders similar to human EDS have been reported in different mammalian species. In the present study, we investigated a female mixed‐breed dog with clinical signs of EDS. Whole‐genome sequencing of the affected dog revealed two missense variants in the TNXB gene, encoding the extracellular matrix protein tenascin XB. In humans, TNXB genetic variants cause classical‐like EDS or the milder hypermobile EDS. The affected dog was heterozygous at both identified variants. Each variant allele was transmitted from one of the case's parents, consistent with compound heterozygosity. Although one of the variant alleles, XM_003431680.3:c.2012G>A, p.(Ser671Asn), was private to the family of the affected dog and absent from whole‐genome sequencing data of 599 control dogs, the second variant allele, XM_003431680.3:c.2900G>A, p.(Gly967Asp), is present at a low frequency in the Chihuahua and Poodle population. Given that TNXB is a functional candidate gene for EDS, we suggest that compound heterozygosity for the identified TNXB variants may have caused the EDS‐like phenotype in the affected dog. Chihuahuas and Poodles should be monitored for EDS cases, which might confirm the hypothesized pathogenic effect of the segregating TNXB variant.     

Altered odor‐induced expression of c‐fos and arg 3.1 immediate early genes in the olfactory system after familiarization with an odor

In adult rats, repeated exposure to an odorant, in absence of any experimentally delivered reinforcement, leads to a drastic decrease in mitral/tufted (M/T) cell responsiveness, not only for the familiar odor but also for other novel odors. In the present study, using two different and complementary in situ hybridization methods, we analyzed the effect of familiarization with an odorant on c‐fos and arg 3.1 mRNA expression levels, and we examined the odor specificity of this effect. Odor exposure induces a specific increase in c‐fos and arg 3.1 expression in some particular olfactory bulb quadrants. Previous familiarization with the test odor results in a decreased expression of both IEGs in these quadrants, leading to the alteration of the odor‐specific pattern of c‐fos and arg 3.1 expression. In contrast, this odor‐specific pattern is not affected when different odors are used for familiarization and test. Similarly, an odor‐specific familiarization effect leading to a reduced c‐fos and arg 3.1 expression was also detected in the cingulate cortex and in the anterior piriform cortex. These results support our hypothesis that the decrease in M/T cell responsiveness following a preceding familiarization with an odorant may be related to a particular form of synaptic plasticity involving changes at the genomic level, and reveals further insight in olfactory information processing and the cellular mechanisms underlying familiarization in the olfactory system. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 61–72, 2002     

Sex‐specific responses of Asian citrus psyllid to volatiles of conspecific and host‐plant origin

Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is the primary vector of Candidatus Liberibacter spp. bacteria that cause citrus greening, a disease of worldwide importance. Olfactometry was employed to test responses of D. citri to odours from intact citrus plants (Mexican lime, Citrus aurantifolia, sour orange, Citrus aurantium, Marsh grapefruit, Citrus paradisi and Valencia orange, Citrus sinensis), citrus plants previously infested with D. citri, and odours of conspecifics including nymphs, adult insects of same and opposite sex, and their products (honeydew), both alone and in combination. In contrast to other studies, psyllids of both sexes were attracted to volatiles of undamaged Mexican lime leaves, whereas undamaged grapefruit attracted only females, and leaves of Valencia and sour orange did not attract either sex. All four plant species attracted female psyllids when previously infested, but only Mexican lime and sour orange‐attracted males. Thus, Citrus species appear to vary in the production of both constituitive and induced volatiles that attract adult psyllids. Volatiles emitted by nymphs did not attract either sex, but psyllid honeydew was attractive to males, likely due to female pheromone residues. Males oriented to the odour of females, whereas the reverse was not true, and neither males nor females oriented to same‐sex volatiles. The addition of conspecific cues (adults, nymphs or honeydew) did not increase female attraction to previously infested leaves, but male response was increased by the presence of adults and honeydew, regardless of plant species. Thus, female psyllids appear to orient more strongly to volatiles of plant origin, whereas males respond more strongly to cues emanating from females and conspecific excretions. These results suggest that female psyllids drive the initial colonization of host plants, whereas males orient to females and infested plants. Identification of the specific volatiles involved may permit their use in monitoring and management of this pest.     

Grooming behaviors of black‐tailed prairie dogs are influenced by flea parasitism,conspecifics, and proximity to refuge

Grooming is a common animal behavior that aids in ectoparasite defense. Ectoparasites can stimulate grooming, and natural selection can also favor endogenous mechanisms that evoke periodic bouts of “programmed” grooming to dislodge or kill ectoparasites before they bite or feed. Moreover, grooming can function as a displacement or communication behavior. We compared the grooming behaviors of adult female black‐tailed prairie dogs (Cynomys ludovicianus) on colonies with or without flea control via pulicide dust. Roughly 91% of the prairie dogs sampled on the non‐dusted colony carried at least one flea, whereas we did not find fleas on two dusted colonies. During focal observations, prairie dogs on the non‐dusted colony groomed at higher frequencies and for longer durations than prairie dogs on the dusted colonies, lending support to the hypothesis that fleas stimulated grooming. However, the reduced amount of time spent grooming on the dusted colonies suggested that approximately 25% of grooming might be attributed to factors other than direct stimulation from ectoparasites. Non‐dusted colony prairie dogs rarely autogroomed when near each other. Dusted colony prairie dogs autogroomed for shorter durations when far from a burrow opening (refuge), suggesting a trade‐off between self‐grooming and antipredator defense. Allogrooming was detected only on the non‐dusted colony and was limited to adult females grooming young pups. Grooming appears to serve an antiparasitic function in C. ludovicianus. Antiparasitic grooming might aid in defense against fleas that transmit the plague bacterium Yersinia pestis. Plague was introduced to North America ca. 1900 and now has a strong influence on most prairie dog populations, suggesting a magnified effect of grooming on prairie dog fitness.     

家犬嗅球组织学结构的性别和年龄差异

用组织学方法研究家犬嗅球的结构,观察家犬嗅球内结构的性别和年龄差异,依据常规HE染色法及数理统计学原理对家犬嗅球各层宽度,主要细胞的数量进行比较统计学分析,探讨嗅球内部结构的发育过程以及性别差异对雌雄动物嗅觉差异的影响。结果表明：雌雄幼年家犬嗅球内各层结构差异不显著;成年家犬也表现出同样的结果,但是成年动物的僧帽细胞形态、数量差异极显著。分析发现,幼年家犬嗅球各层结构都已比较明显,成年家犬嗅球体积和重量明显增加,各层宽度明显变宽,各层细胞密度显著降低,说明嗅球也处在不断的发育完善过程之中。同时僧帽细胞的差异可能是造成雌雄动物嗅觉差别的原因之一。     

Olfactory Snake‐Predator Discrimination in the Cape Ground Squirrel

Small mammals have a number of means to detect and avoid predators, including visual, auditory and olfactory cues. Olfactory cues are particularly important for nocturnal or fossorial species where visual cues would not be as reliable. The Cape ground squirrel (Xerus inauris) is a semi‐fossorial, diurnal mammal from southern Africa. Cape ground squirrels encounter multiple species of predatory snake that pursue individuals underground where visual and social cues are limited. We assessed whether Cape ground squirrels use odours to discriminate between snakes by presenting a non‐venomous snake, a venomous snake and a control odour collected on polyethylene cubes to 11 adult female squirrels from 11 different social groups. Cape ground squirrels responded by inspecting the cube, displaying snake harassment–associated behaviours and decreasing time spent in close proximity to snake odours when compared with a control. They also displayed discrimination between two snake species by increasing the frequency of cube inspection and increasing harassment behaviours with venomous snake odours when compared with non‐venomous snake odours. We conclude that Cape ground squirrels respond with snake‐specific antipredator behaviours when presented olfactory cues alone. Olfactory discrimination may be maintained by the decreased utility of other methods of predator detection: sight and group detection, in below‐ground encounters.     

Low‐concentration heparin suppresses ionomycin‐activated CAMK‐II/EGF receptor‐ and ERK‐mediated signaling in mesangial cells

Heparin and endogenous heparinoids inhibit the proliferation of smooth muscle cells, including renal mesangial cells; multiple effects on signaling pathways are well established, including effects on PKC, Erk, and CaMK‐II. Many studies have used heparin at concentrations of 100 µg/ml or higher, whereas endogenous concentrations of heparinoids are much lower. Here we report the effects of low‐concentration (1 µg/ml) heparin on activation of several kinases and subsequent induction of the c‐fos gene in mesangial cells in response to the calcium ionophore, ionomycin, in the absence of serum factors. Ionomycin rapidly increases the phosphorylation of CaMK‐II (by 30 s), and subsequently of the EGF receptor (EGFR), c‐Src, and Erk 1/2. Low‐dose heparin suppresses the ionomycin‐dependent phosphorylation of EGFR, c‐Src, and Erk 1/2, but not of CaMK‐II, whereas inhibition of activated CaMK‐II reduces phosphorylation of EGFR, c‐Src, and Erk. Our data support a mechanism whereby heparin acts at the cell surface to suppress downstream targets of CaMK‐II, including EGFR, leading in turn to a decrease in Erk‐ (but not c‐Src‐) dependent induction of c‐fos. J. Cell. Physiol. 224: 484–490, 2010. © 2010 Wiley‐Liss, Inc.     

Cortical‐layer‐specific effects of PACAP and tPA on interneuron migration during post‐natal development of the cerebellum

During early post‐natal development of the cerebellum, granule neurons (GN) execute a centripetal migration toward the internal granular layer, whereas basket and stellate cells (B/SC) migrate centrifugally to reach their final position in the molecular layer (ML). We have previously shown that pituitary adenylate cyclase‐activating polypeptide (PACAP) stimulates in vitro the expression and release of the serine protease tissue‐type plasminogen activator (tPA) from GN, but the coordinated role of PACAP and tPA during interneuron migration has not yet been investigated. Here, we show that endogenous PACAP is responsible for the transient arrest phase of GN at the level of the Purkinje cell layer (PCL) but has no effect on B/SC. tPA is devoid of direct effect on GN motility in vitro, although it is widely distributed along interneuron migratory routes in the ML, PCL, and internal granular layer. Interestingly, plasminogen activator inhibitor 1 reduces the migration speed of GN in the ML and PCL, and that of B/SC in the ML. Taken together, these results reveal for the first time that tPA facilitates the migration of both GN and fast B/SC at the level of their intersection in the ML through degradation of the extracellular matrix.

     

Senescence‐associated superoxide dismutase influences mitochondrial gene expression in budding tunicates

A recent study has shown that in the budding tunicate Polyandrocarpa misakiensis, the mitochondrial respiratory chain (MRC) dramatically attenuates the gene activity during senescence. In this study, we examined the possible involvement of superoxide dismutase (SOD) in the attenuation of gene expression of cytochrome c oxidase subunit 1 (COX1) in aged zooids. By RT‐PCR and in situ hybridization, Cu/Zn‐SOD (SOD1) was found to be expressed in most cells and tissues of buds and juvenile zooids but showed a conspicuous decline in senescent adult zooids, except in the gonad tissue in which the cytoplasm of juvenile oocytes was stained heavily. This expression pattern of SOD1 was similar to that of COX1. In contrast to SOD1, Mn‐SOD (SOD2) was expressed constitutively in both somatic and germline tissues of buds, juvenile zooids, and senescent adult zooids. Knockdown of SOD1 by RNAi diminished the gene activity of not only SOD1 but also of COX1. The resultant zooids had transient deficiencies in growth and budding, and they recovered from these deficiencies approximately 1 month later. Our results indicate that in P. misakiensis, SOD1 is a senescence‐associated nuclear gene and that the experimental decline in SOD1 gene expression accompanies the attenuation of MRC gene activity. Although it is uncertain how SOD1 is downregulated during tunicate senescence, the decreased SOD1 activity could be one of the main causes of MRC gene attenuation during normal senescence.     

Novelty‐induced increased expression of immediate‐early genes c‐fos and arg 3.1 in the mouse brain

The detection of novel stimuli is a memory‐dependent process. The presented stimulus has to be compared with memory contents to judge its novelty. In addition, the novelty of stimuli activates attention‐related processes that facilitate memory formation. To determine the involvement of limbic and neocortical brain structures in novelty detection, we exposed mice to a novel gustatory stimulus (0.5% saccharin) added to their drinking fluid. We then compared the novelty‐induced expression of the two immediate‐early genes (IEGs) c‐fos and arg 3.1, with their expression in mice familiarized with the same stimulus or mice not exposed to that stimulus. Exposure to taste novelty increased expression of c‐fos and arg 3.1 mRNA in the cingulate cortex and deep layers of the parietal cortex. In addition, c‐fos mRNA expression was increased in the amygdala and arg 3.1 mRNA was increased in the dentate gyrus. Expression of c‐fos and arg 3.1 was elevated 30 min after the exposure to novelty. For arg 3.1, a second peak of expression was found 4.5 h after presentation of the novel stimulus. Our results indicate that the amygdala, the dentate gyrus, and the cingulate and parietal cortices may be involved in novelty detection and associated cognitive events, and suggest that c‐fos and arg 3.1 play distinct roles in these processes. © 1999 John Wiley & Sons, Inc. J Neurobiol 38: 234–246, 1999     

Olfactory host‐finding behaviour of Oulema melanopus (Coleoptera: Chrysomelidae) and its parasitoid,Tetrastichus julis (Hymenoptera: Eulophidae)

Behavioural responses to the host‐associated olfactory cues have not been completely understood for the cereal leaf beetle, Oulema melanopus, and its principal parasitoid, Tetrastichus julis. We, therefore, investigated the role of olfactory cues in the host‐finding behaviour of these species using olfactory bioassays. Behavioural responses of O. melanopus to odours emanating from intact host plants (wheat, oat, barley) vs. a clean‐air control were tested using multichoice and two‐choice bioassays. For T. julis, responses of naïve and experienced adult female wasps to odours associated with the faecal coat of O. melanopus larvae were measured under multichoice and two‐choice conditions. Our results indicate that olfactory cues are involved in the host‐finding behaviour of both O. melanopus and T. julis. Olfactory responses of O. melanopus were influenced by the sex of the beetle and the physiological stage of adults (reproductively active vs. in reproductive diapause). Females respond to olfactory cues in greater proportions than males, and reproductively active, overwintered adults show greater responsiveness than teneral adults in reproductive diapause. Behavioural responses to cues emanating from different crop species were different in multichoice bioassays but not in two‐choice bioassays. Further, we report for the first time that the olfactory cues associated with the faecal coat of O. melanopus evoke host‐finding behaviour of its parasitoid, T. julis. Naïve female wasps are more likely to use these cues to locate the potential host than experienced females. The results of this investigation provide insights into host finding by both the species and the nature of behavioural response brought about by olfactory stimuli, and the results can help to design strategies to improve parasitoid activity by enhancing the crop environment to generate cues for host finding and to manage O. melanopus populations.     

A cell‐survival factor (N‐acetyl‐L‐cysteine) alters the in vivo fate of constitutively proliferating subependymal cells in the adult forebrain

The adult mouse brain contains a population of constitutively proliferating subependymal cells that surround the lateral ventricle and are the direct progeny of the neural stem cell. Constitutively proliferating cells divide rapidly; 6 days after labeling, 60% of their progeny undergo cell death, 25% migrate to the olfactory bulbs, and 15% continue to proliferate within the subependyma. We have intraventricularly infused a cell survival factor N‐acetyl‐L ‐cysteine (NAC), which is known to have survival effects without concomitant proliferative effects on cells in vitro, and examined the resulting fate of cells spared from the normally occurring cell death. NAC infusion for 5 days results in a five‐fold increase in the number of retrovirally labeled subependymal cells compared to saline‐infused controls. The increase in the number of subependymal cells is directly proportional to the amount of time during which NAC is present and is not due to increased proliferation. While NAC is able to keep all the normally dying progeny alive, the cells spared from death remain confined to the subependyma lining the lateral ventricles and do not migrate to the olfactory bulbs (one normal fate of constitutively proliferating progeny) or into the surrounding brain parenchyma. When animals survive for an additional 6 days following NAC infusion, the number of retrovirally labeled subependymal cells returns to control values, indicating that the continued presence of NAC is necessary for cell survival. These data suggest that preventing cell death is not sufficient to keep all of the progeny of these cells in a proliferative mode. © 2000 John Wiley & Sons, Inc. J Neurobiol 42: 338–346, 2000     

Aberrant neuronal connectivity in CHL1‐deficient mice is associated with altered information processing‐related immediate early gene expression

In humans, loss or alteration of the CHL1/CALL gene may contribute to mental impairment associated with the 3p‐syndrome, caused by distal deletions of the short (p) arm of chromosome 3, and schizophrenia. Mice deficient for the Close Homologue of L1 (CHL1) show aberrant connectivity of hippocampal mossy fibers and olfactory sensory axons, suggesting participation of CHL1 in the establishment of neuronal networks. Furthermore, behavioral studies showed that CHL1‐deficient mice react differently towards novel experimental environments. These data raise the hypothesis that processing of information, possibly novel versus familiar, may be altered in the absence of CHL1. To test this hypothesis, brain activities were investigated after presentation of a novel, familiar, or neutral gustatory stimulus using metabolic mapping with (¹⁴C)‐2‐deoxyglucose (2‐DG) and analysis of mRNA expression of the immediate early genes (IEGs) c‐fos and arg 3.1/arc by in situ hybridization. 2‐DG labeling revealed only small differences between CHL1‐deficient and wild‐type littermate mice. In contrast, while the specific novelty‐induced increase in c‐fos expression was maintained in most of the brain areas analyzed, c‐fos mRNA expression was similar after the novel and familiar taste in several brain areas of the CHL1‐deficient mice. Furthermore, in these mutants, arg 3.1/arc expression was slightly reduced after the novel taste and increased after the familiar taste, leading to a similar arg 3.1/arc mRNA expression after both stimuli. Our results indicate that, in contrast to controls, CHL1‐deficient mice might process novel and familiar information similarly and suggest that the altered neuronal connectivity in these mutants disturbs information processing at the molecular level. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 67–80, 2003     

Drosophila rely on learning while foraging under semi‐natural conditions

Learning is predicted to affect manifold ecological and evolutionary processes, but the extent to which animals rely on learning in nature remains poorly known, especially for short‐lived non‐social invertebrates. This is in particular the case for Drosophila, a favourite laboratory system to study molecular mechanisms of learning. Here we tested whether Drosophila melanogaster use learned information to choose food while free‐flying in a large greenhouse emulating the natural environment. In a series of experiments flies were first given an opportunity to learn which of two food odours was associated with good versus unpalatable taste; subsequently, their preference for the two odours was assessed with olfactory traps set up in the greenhouse. Flies that had experienced palatable apple‐flavoured food and unpalatable orange‐flavoured food were more likely to be attracted to the odour of apple than flies with the opposite experience. This was true both when the flies first learned in the laboratory and were then released and recaptured in the greenhouse, and when the learning occurred under free‐flying conditions in the greenhouse. Furthermore, flies retained the memory of their experience while exploring the greenhouse overnight in the absence of focal odours, pointing to the involvement of consolidated memory. These results support the notion that even small, short lived insects which are not central‐place foragers make use of learned cues in their natural environments.     

Sex allocation and sex‐specific parental investment in an endangered seabird

Biased offspring sex ratio is relatively rare in birds and sex allocation can vary with environmental conditions, with the larger and more costly sex, which can be either the male or female depending on species, favoured during high food availability. Sex‐specific parental investment may lead to biased mortality and, coupled with unequal production of one sex, may result in biased adult sex ratio, with potential grave consequences on population stability. The African Penguin Spheniscus demersus, endemic to southern Africa, is an endangered monogamous seabird with bi‐parental care. Female adult African Penguins are smaller, have a higher foraging effort when breeding and higher mortality compared with adult males. In 2015, a year in which environmental conditions were favourable for breeding, African Penguin chick production on Bird Island, Algoa Bay, South Africa, was skewed towards males (1.5 males to 1 female). Males also had higher growth rates and fledging mass than females, with potentially higher post‐fledging survival. Female, but not male, parents had higher foraging effort and lower body condition with increasing number of male chicks in their brood, thereby revealing flexibility in their parental strategy, but also the costs of their investment in their current brood. The combination of male‐biased chick production and higher female mortality, possibly at the juvenile stage as a result of lower parental investment in female chicks, and/or at the adult stage as a result of higher parental investment, may contribute to a biased adult sex ratio (ASR) in this species. While further research during years of contrasting food availability is needed to confirm this trend, populations with male‐skewed ASRs have higher extinction risks and conservation strategies aiming to benefit female African Penguin might need to be developed.     

Effect of age and sex on the sensitivity of antennal and palpal olfactory cells of houseflies

The olfactory system of newly emerged houseflies (Musca domestica L.; Diptera, Muscidae) is already functional; very few differences compared to sexually mature houseflies exist for the responses to 1‐octen‐3‐ol, amylacetate, 2‐pentanone, 3‐methylphenol, R‐limonene, muscalure, and 6‐methyl‐5‐hepten‐3‐one. Sex differences are also almost absent, except for a higher sensitivity of females to acetic acid. Large differences exist between the sensitivity of antennae and palps to different odours. Antennae are sensitive to all odours tested. Palps are mainly sensitive to 3‐methylphenol and 2‐pentanone, both in percentage of responding cells and in response level. The sensitivity to amyl acetate was similar in palps and antennae. The responses to other odours were low in the palps. We conclude that traps baited with attractive odours may lure houseflies of all ages and both sexes.     

Small but attractive: female‐biased nectar production and floral visitors in a dimorphic shrub

• In sexually dimorphic species, hermaphrodite flowers in gynodioecious species or male flowers in dioecious species are often larger and produce more nectar than their conspecific female flowers. As a consequence, hermaphrodite or male flowers frequently receive more pollinator visits.
• Sex ratio, flower size, floral display, nectar production and floral visits were evaluated in two natural populations of Fuchsia thymifolia, a morphologically gynodioecious but functionally subdioecious insect‐pollinated shrub.
• Sex ratio did not differ from the expected 1:1 in the two studied populations. As expected, hermaphrodite flowers were larger than female flowers, but in contrast to the general pattern, hermaphrodite flowers did not produce nectar or produced much less than female flowers. Flower visitors were flies (68%) and bumblebees (24%), both of which showed a preference for female flowers. No sex difference was detected in either flower longevity or floral display across the flowering season.
• Higher nectar production by females may attract more pollinators, and may be a strategy to enhance female reproductive success in this species. Finally, floral dimorphism and insect preferences did not seem to hamper the maintenance of sub‐dioecy or prevent the evolution of dioecy in F. thymifolia.