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13 recordsLinked to original sources
PubMed2025

Ancestral complexity and constrained diversification of the ant olfactory system.

Communication is a cornerstone of social living, allowing the exchange of information to align goals and synchronize behaviour. Ants, a group of highly successful social insects, have heightened olfactory abilities that are integral to their evolutionary success. Essential for colony cohesion and cooperation, a female-specific olfactory subsystem processes information about nestmate recognition cues (cuticular hydrocarbons), including basiconic sensilla on the antenna and a cluster of specific glomeruli in the antennal lobe. While it has often been linked to ants' social lifestyle, the evolutionary origins and phylogenetic distribution of this system remain unknown. We conducted a comparative exploration of the ant olfactory system across eight major subfamilies, integrating neuroanatomical, chemical and behavioural analyses. Our findings reveal that sophistication of the ant olfactory system has deep evolutionary roots. Moreover, antennal lobe investment is not associated with social traits such as colony size, polygyny or foraging strategies, but correlates with cuticular hydrocarbon profile complexity. Despite neuroanatomical differences, different ant species consistently excel in nestmate discrimination, indicating adaptation to chemical diversity while maintaining reliable social recognition. This suggests that cuticular hydrocarbon profile and neuronal investment in olfactory neuropil have co-evolved to sustain discrimination performance.

Animals↗
PubMed2025

Exploring the associations between preen oil bacterial, chemical and proteomic profiles of passerines.

Preen gland bacteria are thought to be the key producers of preen oil components such as chemosignalling molecules including volatile organic compounds (VOCs) and antimicrobial compounds including peptides and antimicrobial VOCs. However, data on the preen oil bacteriome and chemical composition are limited to a small subset of bird species, and the presence of antimicrobial peptides is largely unexplored. Here, we performed an exploratory study to characterize, for the first time, the preen oil chemical and proteomic profiles and to explore the possible contribution of the bacteriome to the production of preen oil VOCs and antimicrobial peptides (bacteriocins) in eight passerine species, each represented by a single individual. Preen oil bacteriome, chemical and proteomic profiles varied among birds. The bacterial profiles were dominated by the genera Streptococcus, Lactococcus, Corynebacterium and Cutibacterium. The chemical profiles mainly consisted of alcohols, ketones and carboxylic acids. The biological functions primarily associated with the proteomic profiles were proteolysis and response to oxidative stress. Although we were unable to explore a direct association between the bacteriome and chemical profiles, the preen oil contained bacteriocin- and VOC-producing bacterial genera capable of producing detected microbially-derived VOCs (mVOCs), the relative abundance of which varied between birds. Riparian species showed the highest chemical diversity and high abundances of putative preen oil mVOC-producing bacteria, which could suggest habitat-specific adaptations. This exploratory study may significantly contribute to the formulation of hypotheses on the potential role of host ecological factors in the variation of preen oil bacterial, chemical and proteomic profiles in passerines.

Animals↗
PubMed1977

The anatomical relations of the ductus vomeronasalis and the occurrence of taste buds in the papilla palatina of Nycticebus coucang (primates, prosimiae) with remarks on strepsirrhinism.

Nycticebus coucang is typically strepsirrhine. This condition is basically the same in all prosimians except Tarsius. The rhinarium shows a labial part; the marked furrow in its median plane clefts the margin of the upper lip. The latter is attached to the gum between the median incisors by means of paired folds (not corresponding to a frenulum labii superioris). The labial cleft is continued in the sulcus papillae palatinae. The ductus vomeronasalis opens into the ductus nasoplatinus which, in turn, enters the aboral part of the sulcus palatinus. Thus strepsirrhinism provides, occasionally, an open communication of the olfactory systems (nose, vomeronasal organ) with the environment in front of the rhinarium. Strepsirrhine primates possess an internarium very similar to the one of platyrrhine monkeys. The shape of the nostrils is not characteristics for strepsirrhinism. A split-lip condition is likely ancestral to the complete lip condition, since it is found in several stems of mammals, especially in archaic forms. Strepsirrhinism, such as in lemuroid prosimians, is probably just one case of the primitive split-lip condition. Therefore, a median furrow in the external hairy skin of the upper lip, found in some platyrrhine monkeys, could be a rudiment of a cleft, indicating that a kind of a split lip condition was ancestral to the undivided lips of platyrrhine monkeys. Taste buds occur in the epithelium of the lateral surface of the papilla palatina of Nycticebus. Other lorisid prosimians have not been studied in this respect. The taste buds test water soluble substances entering the sulcus either way. These substances may come from the environment entering the sulcus through the labial cleft.

Animals↗
PubMed1979

Neurobehavioral evidence for the involvement of the vomeronasal system in mammalian reproduction.

Jacobson's organ of the vomeronasal system is found in every order of mammals with the possible exception of Cetacea. The equivocal evidence claiming a vestigial or absent organ in humans is reviewed. Based upon anatomical considerations, the sensory epithelium of Jacobson's organ is one of five possible sensory components within the nasal cavity. Many methods designed to test the role of olfaction (sensu strictu) in physiology and behavior do not discriminate among the possible systems. Therefore, erroneous conclusions may have been drawn from the results of intervention experiments. The central neuroanatomical projections of the vomeronasal and olfactory systems are different and relatively independent of each other. The vomeronasal system reciprocally communicates with central areas concerned with reproductive events. On the other hand, the olfactory system may subserve individual maintenance tasks (e.g., feeding). As a periscope from the diencephalon, the vomeronasal system may monitor exogenous hormones, "pheromones".

Animals↗
PubMed2022

Signatures for viral infection and inflammation in the proximal olfactory system in familial Alzheimer's disease.

Alzheimer's disease (AD) is characterized by deficits in olfaction and olfactory pathology preceding diagnosis of dementia. Here we analyzed differential gene and protein expression in the olfactory bulb (OB) and tract (OT) of familial AD (FAD) individuals carrying the autosomal dominant presenilin 1 E280A mutation. Compared to control, FAD OT had increased immunostaining for β-amyloid (Aβ) and CD68 in high and low myelinated regions, as well as increased immunostaining for Iba1 in the high myelinated region. In FAD samples, RNA sequencing showed: (1) viral infection in the OB; (2) inflammation in the OT that carries information via entorhinal cortex from the OB to hippocampus, a brain region essential for learning and memory; and (3) decreased oligodendrocyte deconvolved transcripts. Interestingly, spatial proteomic analysis confirmed altered myelination in the OT of FAD individuals, implying dysfunction of communication between the OB and hippocampus. These findings raise the possibility that viral infection and associated inflammation and dysregulation of myelination of the olfactory system may disrupt hippocampal function, contributing to acceleration of FAD progression.

Humans↗
PubMed1978

Effects of lesions of globus pallidus on species-typical display behavior of squirrel monkeys.

In a study of brain mechanisms underlying species-typical communication, systematic testing has been conducted on the effects of cerebral lesions on the mirror display of squirrel monkeys. The mirror display is a highly predictable variation of a naturally occurring display used by male squirrel monkeys in a show of aggression, in courtship and in greeting. Of the 5 features of the display, vocalization, thigh-spreading and forward thrusts of the erect phallus are the major and most regularly occurring manifestations, constituting the so-called trump display. Testing has been performed on more than 100 animals with lesions in various structures of the brain. The present report describes the positive effects of electro-coagulation of certain parts of the globus pallidus. Lesions of the medial segment have resulted in an enduring elimination or fragmentation of the trump display. Recovery of the display may occur with lesions predominantly involving the external segment, while destruction of the caudalmost pallidum is without effect. A variety of evidence indicates that the behavioral changes are not due to a deterioration of health, motor disabilities, seasonal factors or motivation. When weighed against the negative or transitory effects of lesions of numerous other structures of the brain, the present findings support the hypothesis that the striatal complex plays a basic role in the organized expression of species-typical behavior.

Animal Communication↗
PubMed1976

[Diencephalic cyst--in relation to other midline dysraphism (author's transl)].

The abnormal midline cyst of diencephalic origin was termed "diencephalic cyst" by Brocklehurst in 1973. Since then, several case reports of so-called "diencephalic cyst" have appeared, but its clinical picture, especially its relation to other midline dysraphisms, does not seem to be well understood. Our experience with four cases of so-called "diencephalic cyst" were reported and their relation to holoprosencephaly as well as simple agenesis of corpus callosum was discussed. (1) In all of these cases, there was an abnormal space in the midline which freely communicated with the lateral ventricle. In the first two cases, their clinical pictures as well as the features of contrast studies were typical of alobar holoprosencephaly. In the third case, the absence of the olfactory tract, the incompletely separated cerebrum, and the monoventricle were confirmed at autopsy. In the last case, the ventricle was also incompletely separated. From these observations, such a malformation should better be considered as a variant of holoprosencephaly, and it would not be appropriate to classify this malformation, as Brocklehurst claimed, as "a maldevelopment lying between the group associated with anterior neuropore closure and prosencephalization (anterior encephaloceles and holoprosencephaly) and the group associated with maldevelopment of the hind brain (cerebellar and fourth ventricle encephaloceles and Dandy-Walker cyst of the rhombencephalon)." (2) This malformation is apparently formed before the 40 mm stage of the embryo, since by this time the diencephalic roof has already sunk to the level of the adult form. This maldevelopment should be clearly differenciated from simple agenesis of the corpus callosum which is formed after the 60 mm stage of the embryo. In simple agenesis of the corpus callosum, the deep venous system might take an abnormal course, but is well formed, whereas in holoprosencephaly or so-called "diencephalic cyst", the internal cerebral vein as well as the straight sinus and the inferior sagittal sinus is absent. (3) In all of our cases, there was an abnormal space posterior and inferior to the elevated lateral sinus. Autopsy done in two cases revealed that this abnormal space was a Dandy-Walker cyst in one case, the the dorsal sack of diencephalic origin in the other case. The latter case tells that in the cases of holoprosencephaly the lateral sinus does not necessarily mark the boundary between the cerebrum and the cerebellum. (4) "Diencephalic cyst" often accompanies severe hydrocephalus. However, even with successful surgical treatment of hydrocephalus, the outcome of intelligence in these cases would be grave.

Agenesis of Corpus Callosum↗
PubMed1979

Blockade of progesterone-induced increase in hypothalamic luteinizing hormone-releasing hormone levels and serum gonadotropins by intrahypothalamic implantation of 6-hydroxydopamine.

The present study was undertaken to identify the hypothalamic locus where norepinephrine (NE) nerve terminals communicate with luteinizing hormone-releasing hormone (LH-RH)-containing neurons involved in the stimulatory feedback action of gonadal steroids on LH and FSH release. Ovariectomized rats received estradiol benzoate (10 microgram/rat s.c.) on day 0. Intracranial implants containing either 6-hydroxydopamine (6-OHDA), to destroy NE terminals, or cocoa butter (controls) were placed bilaterally in the suprachiasmatic nucleus (SCN), medial basal hypothalamus (MBH) or olfactory tubercle (OT) on day 1. Progesterone (P, 5 mg/rat s.c.) was administered at 10.00 h on day 2 to elicit increases in serum LH and FSH and the MBH LH-RH levels in the afternoon. Implantation of 6-OHDA in the SCN resulted in a marked depletion of NE in and around the region of the SCN in the preoptic-anterior hypothalamic area (POA-AH) without adversely affecting dopamine (DA) concentrations, and blocked the P-induced afternoon increase in the MBH LH-RH and serum gonadotropin levels. Similar reduction in the MBH NE concentrations occurred following placement of 6-OHDA in the MBH; however, these as well as implants in the OT were ineffective in suppressing the P-induced effects. These studies show that functional integrity of the SCN regions is critical in manifestation of the P-induced rise in the MBH LH-RH activity, and this region in the POA-AH, therefore, may be the primary locus of synaptic communication between NE terminals and LH-RH neurons.

Animals↗
PubMed1977

Arhinencephaly (holoprosencephaly) associated with external hydrocephaly.

A female infant, weighing 2,263 g had been spontaneously delivered at the 33rd week of gestation. The only noticeable abnormality was a cleft palate, but within the next few days, she developed low temperature, spastic movements in the extremities, and depressed respiration. These abnormalities soon became worse and she died on the 12th day. Clinically, she was not suspected of having malformations of the brain, but on autopsy, an external hydrocephaly (400 ml) and small arhinencephalic brain (75 g) were noted. In the brain, the growth of the diencephalon was exceedingly poor but the growth of the rhombencephalon was relatively favorable. The olfactory bulbi and tracts in the telencephalon were absent. These findings were similar to those seen in cases of arhinencephaly (or holoprosencephaly). In the cerebral ventricles, the lateral ventricles and the IVth ventricle were enlarged, but the IIIrd ventricle could not be identified. Communication could only be found between the lateral apertures of the IVth ventricle and the subarachnoidal spaces.

Brain↗
PubMed2025

Transcriptional interference gates monogenic odorant receptor expression in ants.

Communication is crucial to social life, and in ants, it is mediated primarily through olfaction. Ants have more odorant receptor (OR) genes than any other group of insects, generated through tandem duplications that produce large genomic arrays of related genes. The mechanism by which olfactory sensory neurons (OSNs) produce a single functional OR from these arrays remains unclear. In ant OSNs, only mRNA from one OR in an array is exported into the cytoplasm, while upstream genes are silent and transcripts from downstream genes remain nuclear. Here, we show that readthrough transcription in the downstream direction generates non-translated transcripts. We also find that OR promoters are bidirectional, producing antisense long non-coding RNAs. We suspect that neither readthrough nor antisense transcription produces functional RNA but that bidirectional transcription alone is critical to suppressing the expression of all other OR genes in a tandem array. Finally, we present evidence that this regulatory architecture is conserved across ants and bees, suggesting that this mechanism for functionally monogenic OR expression is widespread in insects with expanded OR repertoires.

Animals↗
PubMed1978

Diurnal behavior of Lemur mongoz at Ampijoroa, Madagascar.

Lemur mongoz was observed for 28 h between February and July in Ampijoroa, northwestern Madagascar. The animals were diurnal, with peaks of activity in mid-morning and late afternoon. This finding contrasts with other reports that L. mongoz at the same site and somewhat later in the year are nocturnal. Group size was three or four. L. mongoz associated with L. fulvus during group progression and feeding and when giving alarm responses to man. Vocal signals consist of a range of intergrading grunts and shrieks; olfactory signals of apparent scent marking with the anogenital region, forehead, and palms of the hands; visual signals of mainly unritualized body movements and postures. All of these signals are quite similar to signals of L. fulvus.

Animal Communication↗