Diurnal Lifestyle Research Articles

The Ultramorphology and Sexual Dimorphism of Antennae and Sensilla in the Pale Grass Blue, Pseudozizeeria maha (Lepidoptera: Lycaenidae).

The pale grass blue, Pseudozizeeria maha, is a small lycaenid butterfly widely distributed across Asia. Due to its exclusively diurnal lifestyle and conspicuous sexual dimorphism in wing coloration, vision has traditionally been regarded as the primary sensory system driving various behaviors. However, non-visual sensory systems related to sex-specific behavioral responses, such as antennae, have received far less attention. This study investigated the morphological characteristics and sensilla types of the antennae in adult P. maha using scanning electron microscopy, with a focus on potential sexual dimorphism. The antennae of adult P. maha are clavate, with no significant sexual differences in overall morphology. Six types of antennal sensilla were identified: Böhm bristles, sensilla squamiformia, sensilla trichodea, sensilla chaetica, sensilla basiconica, and sensilla coeloconica, with no sexual dimorphism observed in their morphological types or dimensions. Remarkably, the sensilla coeloconica exhibit significant sexual dimorphism, with a more prominent presence in females. This finding suggests that female P. maha may rely more on olfactory cues for some sex-specific behaviors, such as oviposition site selection.

Histomorphological Investigation of the Eye of the Tree Squirrel: A Preliminary Study

Abstract Squirrels are diurnal rodents with high visual acuity including unique properties well-suited for their natural environment. This study was conducted to explore some ocular microscopic features of tree-harbouring squirrels in the University of Ibadan, Ibadan, Nigeria. Two male squirrels were cage-trapped within the University premises. Light microscopic analysis was carried on paraffin-embedded eye samples harvested from the animals. The densely compacted stromal fibres, 351 ± 52.5 µm thick, formed the thickest part of the cornea, and the basement membrane of the corneal epithelium, 63.8 ± 13.0 µm thick, was notably positive with Periodic Acid Schiff (PAS) stain. Strong pigmentation was present at the choroid as well as the iridal and ciliary epithelia. The multiple layering of the retinal structure exhibited densely packed ganglion cells at the ganglion cell layer which together with the nerve fibre layer was observed to be thinnest at the more peripheral portion but becomes thicker towards the optic disc. Strongly positive glia fibrillary acidic protein (GFAP+) cells with their abundant fibrous processes were demonstrated immunohistochemically at the retinal nerve fibre layer and the optic nerve. Histological features of the retinal cellular components of the tree squirrels investigated has thus highlighted the structural adaptation of these animal species to their environmental arboreal habitat and diurnal lifestyle. Findings from this study, while further noted to be similar to that in human, showed that African tree squirrels represent promising rodent model for human retinal/ocular research.

Degeneration of the Olfactory System in a Murid Rodent that Evolved Diurnalism.

In mammalian research, it has been debated what can initiate an evolutionary tradeoff between different senses, and the phenomenon of sensory tradeoff in rodents, the most abundant mammalian clade, is not evident. The Nile rat (Arvicanthis niloticus), a murid rodent, recently adapted to a diurnal niche through an evolutionary acquisition of daylight vision with enhanced visual acuity. As such, this model provides an opportunity for a cross-species investigation where comparative morphological and multi-omic analyses of the Nile rat are made with its closely related nocturnal species, e.g. the mouse (Mus musculus) and the rat (Rattus norvegicus). Thus, morphological examinations were performed, and evolutionary reductions in relative sizes of turbinal bone surfaces, the cribriform plate, and the olfactory bulb were discovered in Nile rats. Subsequently, we compared multiple murid genomes, and profiled olfactory epithelium transcriptomes of mice and Nile rats at various ages with RNA sequencing. The results further demonstrate that, in comparison with mouse olfactory receptor (OR) genes, Nile rat OR genes have experienced less frequent gain, more frequent loss, and more frequent expression reduction during their evolution. Furthermore, functional degeneration of coding sequences in the Nile rat lineage was found in OR genes, yet not in other genes. Taken together, these results suggest that acquisition of improved vision in the Nile rat has been accompanied by degeneration of both olfaction-related anatomical structures and OR gene repertoires, consistent with the hypothesis of an olfaction-vision tradeoff initiated by the switch from a nocturnal to a diurnal lifestyle in mammals.

Physiological properties of the visual system in the Green Weaver ant, Oecophylla smaragdina

The Green Weaver ants, Oecophylla smaragdina are iconic animals known for their extreme cooperative behaviour where they bridge gaps by linking to each other to build living chains. They are visually oriented animals, build chains towards closer targets, use celestial compass cues for navigation and are visual predators. Here, we describe their visual sensory capacity. The major workers of O. smaragdina have more ommatidia (804) in each eye compared to minor workers (508), but the facet diameters are comparable between both castes. We measured the impulse responses of the compound eye and found their response duration (42 ms) was similar to that seen in other slow-moving ants. We determined the flicker fusion frequency of the compound eye at the brightest light intensity to be 132 Hz, which is relatively fast for a walking insect suggesting the visual system is well suited for a diurnal lifestyle. Using pattern-electroretinography we identified the compound eye has a spatial resolving power of 0.5 cycles deg−1 and reached peak contrast sensitivity of 2.9 (35% Michelson contrast threshold) at 0.05 cycles deg−1. We discuss the relationship of spatial resolution and contrast sensitivity, with number of ommatidia and size of the lens.

New insights into the retinal microstructure-diurnal activity relationship in the African five-lined skink (Trachylepis quinquetaeniata) (Lichtenstein, 1823)

BackgroundThe retinae of diurnal vertebrates have characteristics. Most lizards are strictly diurnal, and their retinal morphology is still unknown.Materials and methodsThe retina of the African five-lined skink (Trachylepis quinquetaeniata) was studied using light and transmission electron microscopy.ResultsThe retina's ten layers were all detected. The inner nuclear layer was the thickest by an average of 67.66 μm, and the inner plexiform layer was 57.564 μm. There were elliptical, long cylindrical, and spherical melanosomes (small and large) in the pigment epithelial layer of the retina. The cylindrical melanosomes had a large area on the lateral surfaces of cones to increase light scatter absorption. The photoreceptor layer of the retina had cones only. There were single and double cones, with the double cones consisting of principal and accessory cones. The cones had inner and outer segments separated by oil droplets. A spherical paraboloid body existed between the limiting membrane and the ellipsoid. All single cones had a paraboloid, and double cones had a large paraboloid in the accessory cone. The presence of paraboloids and large ellipsoids with mitochondria of varying sizes may have helped focus the light on cone segments.ConclusionThe African five-lined skink's eye was light-adapted due to a variety of retinal specializations related to the demands of its diurnal lifestyle in its environment.

Genomic signatures of the evolution of a diurnal lifestyle in Strigiformes

Understanding the targets of selection associated with changes in behavioral traits represents an important challenge of current evolutionary research. Owls (Strigiformes) are a diverse group of birds, most of which are considered nocturnal raptors. However, a few owl species independently adopted a diurnal lifestyle in their recent evolutionary history. We searched for signals of accelerated rates of evolution associated with a diurnal lifestyle using a genome-wide comparative approach. We estimated substitution rates in coding and noncoding conserved regions of the genome of seven owl species, including three diurnal species. Substitution rates of the noncoding elements were more accelerated than those of protein-coding genes. We identified new, owl-specific conserved noncoding elements as candidates of parallel evolution during the emergence of diurnality in owls. Our results shed light on the molecular basis of adaptation to a new niche and highlight the importance of regulatory elements for evolutionary changes in behavior. These elements were often involved in the neuronal development of the brain.

A new scaly ommatine beetle (Coleoptera: Archostemata) from mid-Cretaceous Kachin amber

A rare archostematan beetle, Lepidomma beuteli sp. nov. (Insecta: Coleoptera: Archostemata), is described based on a well-preserved specimen from mid-Cretaceous Kachin amber. It is the fourth species of the genus from the same locality that can be distinguished from the other three congeners by its elongated scape, exposed neck and, especially, ridged pronotum. The new species was probably adapted to a surficial, arboreal, diurnal lifestyle from its external appearance. The specialization of scaly elytra also helps to reveal the importance of scale development in mid-Cretaceous Kachin beetles.

Dynamic Inventory of Intermediate Metabolites of Cyanobacteria in a Diurnal Cycle.

SummaryCyanobacteria are gaining importance both as hosts for photoautotrophic production of chemicals and as model systems for studies of diurnal lifestyle. The proteome and transcriptome of cyanobacteria have been closely examined under diurnal growth, whereas the downstream effects on the intermediary metabolism have not received sufficient attention. The present study focuses on identifying the cellular metabolites whose inventories undergo dramatic changes in a fast-growing cyanobacterium, Synechococcus elongatus PCC 11801. We identified and quantified 67 polar metabolites, whose inventory changes significantly during diurnal growth, with some metabolites changing by 100-fold. The Calvin-Benson-Bassham cycle intermediates peak at midday to support fast growth. The hitherto unexplored γ-glutamyl peptides act as reservoirs of amino acids. Interestingly, several storage molecules or their precursors accumulate during the dark phase, dispelling the notion that all biosynthetic activity takes place in the light phase. Our results will guide metabolic modeling and strain engineering of cyanobacteria.

Fuelling on the wing: sensory ecology of hawkmoth foraging

Hawkmoths (Lepidoptera, Sphingidae) comprise around 1500 species, most of which forage on nectar from flowers in their adult stage, usually while hovering in front of the flower. The majority of species have a nocturnal lifestyle and are important nocturnal pollinators, but some species have turned to a diurnal lifestyle. Hawkmoths use visual and olfactory cues including CO2 and humidity to detect and recognise rewarding flowers; they find the nectary in the flowers by means of mechanoreceptors on the proboscis and vision, evaluate it with gustatory receptors on the proboscis, and control their hovering flight position using antennal mechanoreception and vision. Here, we review what is presently known about the sensory organs and sensory-guided behaviour that control feeding behaviour of this fascinating pollinator taxon. We also suggest that more experiments on hawkmoth behaviour in natural settings are needed to fully appreciate their sensory capabilities.

EvoDevo in owl ear asymmetry—The little owl (Athene noctua)

Owls are well adapted to nocturnal hunting. This includes vision tuned to low level light conditions, silent flight, and asymmetrical ears. Asymmetrical ears facilitate sound localization and evolved up to seven times independently in the evolutionary history of owls. However, there are also owl species with a crepuscular or diurnal lifestyle, like the little owl (Athene noctua), that have symmetrical ears as adults. Here we show that a small, but significant ear asymmetry occurs in the embryonic development of little owls, despite the presence of symmetrical ears in adults. In the asymmetric period, the left ear opening is bigger in area than its counterpart on the right. The asymmetry in the little owl occurs in the same stages at which the asymmetry in the barn owl (Tyto furcata) develops, but in the little owl the asymmetry vanishes shortly before hatching. Asymmetries in the size of the ear openings are also found in the adults of other owl species, most of them belonging to the genus Strix. We interpret our finding as an indication of a secondarily evolved diurnal activity in little owls. Further, ear asymmetry might be more deeply rooted in the evolution of owls than previously assumed.

World genera of Mastigitae: review of morphological structures and new ecological data (Coleoptera: Staphylinidae: Scydmaeninae)

Mastigitae comprise most unusual ant-like stone beetles, showing intriguing morphological characters and ecological adaptations. The largest adults among Scydmaeninae can be found in this group; some reaching nearly 9 mm in length, but there are also adults as small as 1.10 mm. Members of Leptomastacini are microphthalmous and depigmented; Mastigini are often black or contrastingly bicolored and have diurnal life style, adults of some species climbing bushes and trees. Papusini inhabit the driest North American deserts and are active during the warmest time of the year; other taxa live in subtropical forests; some are known to enter caves. Adults of some genera have enigmatic modifications of maxillary palps, postgenae or antennae, whose functions still remain unknown. In one genus the male genitalia are enormously elongate, so that these beetles have evolved a method of copulation not known in any other Coleoptera. The evolutionary history of Mastigitae is documented by fossils since the Upper Cretaceous, and extinct forms are even more 'extreme' in their spiny antennae and unusually elongate appendages than their extant relatives. Although phylogenetic hypotheses have been proposed to clarify the relationships and classification of Mastigitae, morphological structures of most genera remain undescribed. They are reviewed in the present synopsis, with detailed descriptions and illustrations of adult structures of all extant genera (Ablepton, Leptomastax, Taurablepton, Mastigus, Palaeostigus, Stenomastigus, Leptochromus, Clidicus and Papusus), with a brief review of known larval forms and fossils. Novel ecological data are given, with emphasis on habitat preferences and feeding behavior. The 'springtail trap' hypothesis for the spiny antennae of Mastigini is rejected, based on field observations and laboratory experiments. For the first time, details of feeding for Palaeostigus and Leptomastax are described. A checklist of species is given, and the main problems related to the classification, phylogeny and ecology of Mastigitae are discussed.

Segmental duplications and evolutionary acquisition of UV damage response in the SPATA31 gene family of primates and humans

BackgroundSegmental duplications are an abundant source for novel gene functions and evolutionary adaptations. This mechanism of generating novelty was very active during the evolution of primates particularly in the human lineage. Here, we characterize the evolution and function of the SPATA31 gene family (former designation FAM75A), which was previously shown to be among the gene families with the strongest signal of positive selection in hominoids. The mouse homologue for this gene family is a single copy gene expressed during spermatogenesis.ResultsWe show that in primates, the SPATA31 gene duplicated into SPATA31A and SPATA31C types and broadened the expression into many tissues. Each type became further segmentally duplicated in the line towards humans with the largest number of full-length copies found for SPATA31A in humans. Copy number estimates of SPATA31A based on digital PCR show an average of 7.5 with a range of 5–11 copies per diploid genome among human individuals. The primate SPATA31 genes also acquired new protein domains that suggest an involvement in UV response and DNA repair. We generated antibodies and show that the protein is re-localized from the nucleolus to the whole nucleus upon UV-irradiation suggesting a UV damage response. We used CRISPR/Cas mediated mutagenesis to knockout copies of the gene in human primary fibroblast cells. We find that cell lines with reduced functional copies as well as naturally occurring low copy number HFF cells show enhanced sensitivity towards UV-irradiation.ConclusionThe acquisition of new SPATA31 protein functions and its broadening of expression may be related to the evolution of the diurnal life style in primates that required a higher UV tolerance. The increased segmental duplications in hominoids as well as its fast evolution suggest the acquisition of further specific functions particularly in humans.

Phylogeny of the subfamilyLarentiinae (Lepidoptera:Geometridae): integrating molecular data and traditional classifications

AbstractLarentiinae are the second largest subfamily ofGeometridae, with more than 6200 described species. Despite recent advances in molecular systematics of geometrid moths, phylogenetic relationships between the numerous subgroups ofLarentiinae are poorly known. In this study we present the most comprehensive attempt to date to resolve the phylogeny ofLarentiinae, having sampled at least one species from all currently recognized 23 tribes. Fragments of one mitochondrial (COI) and eight nuclear (EF‐1α,WGL,GAPDH,RPS5,IDH,MDH,CADand28S) genes were sequenced, for a total of 6939 bp. Maximum likelihood andBayesian analyses resulted in identical well‐resolved phylogenetic trees, which had maximum or near‐maximum support values at most nodes. Almost all conventionally recognized tribes represented by more than one genus were found to be monophyletic. Close to the root ofLarentiinae, six tribes branch off the main lineage one after another, withDyspteridini being sister to all other members of the subfamily. The rest of larentiines are divided into two very diverse lineages, comprising eight and at least ten tribes, respectively. There were just three findings incongruent with the conventional tribal subdivision of the subfamily. First, the generaCollixGuenée andAnticollixProut formed a separate, previously unrecognized but well‐supported clade at the tribe level. Second, thePalaearctic genusPelurgaHübner was placed apart fromLarentiaTreitschke andMesoleucaHübner, which were the other members ofLarentiini in this analysis. Third,Cataclysmini appeared together with genera belonging toXanthorhoini, leaving the latter paraphyletic. TheNeotropic genusOligopleuraHerrich‐Schäffer is shown to belong to the tribeEuphyiini (comb.n.) according to both molecular data and male genital morphology. The results and the tribal classification ofLarentiinae are discussed with reference to the principal publications since the end of the 19thCentury. We conclude that the current tribal classification ofLarentiinae is not controversial from the phylogenetic point of view and that its increasing complexity has merely reflected the accumulation of information, mainly through different methods of biosystematic study having become available for researchers. Our results indicate that diurnal lifestyle, accompanied by conspicuous coloration, has evolved independently in several subgroups ofLarentiinae.

Elucidating temporal resource allocation and diurnal dynamics in phototrophic metabolism using conditional FBA.

The computational analysis of phototrophic growth using constraint-based optimization requires to go beyond current time-invariant implementations of flux-balance analysis (FBA). Phototrophic organisms, such as cyanobacteria, rely on harvesting the sun’s energy for the conversion of atmospheric CO2 into organic carbon, hence their metabolism follows a strongly diurnal lifestyle. We describe the growth of cyanobacteria in a periodic environment using a new method called conditional FBA. Our approach enables us to incorporate the temporal organization and conditional dependencies into a constraint-based description of phototrophic metabolism. Specifically, we take into account that cellular processes require resources that are themselves products of metabolism. Phototrophic growth can therefore be formulated as a time-dependent linear optimization problem, such that optimal growth requires a differential allocation of resources during different times of the day. Conditional FBA then allows us to simulate phototrophic growth of an average cell in an environment with varying light intensity, resulting in dynamic time-courses for all involved reaction fluxes, as well as changes in biomass composition over a diurnal cycle. Our results are in good agreement with several known facts about the temporal organization of phototrophic growth and have implications for further analysis of resource allocation problems in phototrophic metabolism.

Organization of the Olfactory System of Nymphalidae Butterflies

Olfaction is in many species the most important sense, essential for food search, mate finding, and predator avoidance. Butterflies have been considered a microsmatic group of insects that mainly rely on vision due to their diurnal lifestyle. However, an emerging number of studies indicate that butterflies indeed use the sense of smell for locating food and oviposition sites. To unravel the neural substrates for olfaction, we performed an anatomical study of 2 related butterfly species that differ in food and host plant preference. We found many of the anatomical structures and pathways, as well as distribution of neuroactive substances, to resemble that of their nocturnal relatives among the Lepidoptera. The 2 species differed in the number of one type of olfactory sensilla, thus indicating a difference in sensitivity to certain compounds. Otherwise no differences could be observed. Our findings suggest that the olfactory system in Lepidoptera is well conserved despite the long evolutionary time since butterflies and moths diverged from a common ancestor.

Is diurnal lifestyle altered during Ramadan in professional Muslim athletes?

Lifestyle and circadian patterns are disturbed in Muslims during the holy month of Ramadan. The aims of this study were to establish how the timing of sleep was influenced by fasting diurnal requirements and how training practices were altered in professional soccer players by comparing behaviour over the Ramadan month to that displayed in the four weeks immediately following. Altogether 20 players from a top professional club in an Islamic country were monitored for eight weeks. Environmental conditions were similar between the two periods. The players adjusted to the privations of Ramadan by altering bedtime to later at night and spending longer in bed than in the month following. Timing of sleep was delayed significantly during Ramadan, a mean delay in bedtime (199 ± 47 min) and an increase in sleep length (99 ± 42 min) being observed during Ramadan. The training load, as indicated by training impulse (TRIMP) scores, did not vary between Ramadan and the following four weeks, although the duration of training sessions was shortened after two weeks of Ramadan. Core temperature responses (38.4 ± 0.6 and 38.5 ± 0.7°C) to training and fluid losses were similar between the two four-week periods. Fluid intake (r = 0.81; P < 0.05) and fluid loss (R = 0.76; P < 0.05) were significantly correlated with TRIMP scores. Urine osmolality (825 ± 143 mOsmol/kg H2O) was higher during Ramadan compared to the reference period that followed (708 ± 155 mOsmol/kg H2O); there was also a significant difference during the weeks of Ramadan (F 3,27 = 3.42; P < 0.05), pair-wise comparisons revealing a significant difference (P = 0.038) between week 1 and week 4, a mean reduction of 159 mOsmol/kg H2O. The results demonstrate how these players responded to the fasting requirements of Ramadan and cannot be generalised to non-professional athletes or individuals adopting more devout programmes.

The topography of cone photoreceptors in the retina of a diurnal rodent, the agouti (Dasyprocta aguti)

The presence, density distribution, and mosaic regularity of cone types were studied in the retina of the diurnal agouti, Dasyprocta aguti. Longwave-sensitive (L-) and shortwave-sensitive (S-) cones were detected by antibodies against the respective cone opsins. L- and S-cones were found to represent around 90 and 10% of the cone population, respectively. There was no evidence for L- and S-opsin coexpression in agouti cones. L-cone densities were highest, up to 14,000/mm2, along a horizontal visual streak located about 2-3 mm dorsal to the optic nerve, and the L-cone distribution showed a dorsoventral asymmetry with higher densities in ventral (about 10,000/mm2) than in dorsal (about 4000/mm2) retinal regions. This L-cone topography parallels the agouti's ganglion cell topography. S-cones had a peak density of 1500-2000/mm2 in the central retinal region but did not form a visual streak. Their distribution also showed a dorsoventral asymmetry with densities around 600/mm2 in dorsal and around 1000/mm2 in ventral retinal regions. The patterning of cone arrays was assessed by the density recovery profile analysis. At all eccentricities evaluated, the S-cone mosaic less efficiently packed than the L-cone mosaic. Rod densities ranged from 47,000/mm2 in peripheral to 64,000/mm2 in central retina, and rod:cone ratios were 4:1-9:1. The comparatively low rod density and high cone proportion appear well adapted to the diurnal lifestyle of the agouti.

Vitamin D3-Mediated Regulation of Antimicrobial Peptide Expression by Ancient Transposable Elements Conserved Only in Humans and Primates.

The seco-steroid hormone 1,25(OH)2D3 (vitamin D3) induces the expression of the cathelicidin antimicrobial peptide (CAMP/CAP18/LL37) and human β defensin 4 (DEFB4/hβ D2) in human bone marrow cells, acute myeloid leukemia cells, monocytes, neutrophils, skin, and epithelial cell lines. It is mediated by a DR3-type vitamin D response element (VDRE; two 6-bp direct repeats [DR] separated by 3-bp) located in the promoter of each gene. We examined a wide range of human cell types and found that induction is most robust in myeloid cell types and does not occur in murine cells. Induction is not conserved in non-primate mammals as indicated by the absence of the VDRE in the murine, rat, and canine CAMP and DEFB4 promoters. The VDRE of the CAMP promoter is located in a short-interspersed nucleotide element (SINE) of the Alu-Sx subfamily of primate transposable elements. The DEFB4 VDRE is not located within such an element. We hypothesized that this unique vitamin D3-regulated expression of antimicrobial peptides is evolutionarily conserved in all primates. To test this, we amplified the promoter regions containing the CAMP and DEFB4 VDREs by PCR from the genomic DNAs of either humans, apes (chimpanzee, bonobo, gorilla & orangutan), Old World Monkeys (OWMs; rhesus macaque, pitailed macaque & African green monkey) or New World Monkeys (NWMs; common marmoset, common woolly monkey, black-handed spider monkey & red-chested tamari). Sequence analysis revealed the CAMP VDRE is highly conserved in all groups. Only African green monkey possessed a G to A change in the second DR6. Interestingly, the size of the PCR product (SINE plus flanking sequence) for rhesus macaque (OWM), tamari (NWM) and marmoset (NWM) was about 880 bp. For all others, the size was about 580 bp. The additional 300 bp of sequence was nearly identical to the first 300 bp of the shorter SINE. In other words, the larger SINE appears to have resulted from a duplication event or insertion of a second SINE into the first. This 880 bp SINE is present in the recently deposited rhesus macaque genome at the UCSC Genome Bioinformatics site. The hBD2/DEFB4 VDRE is highly conserved, too. The bonobo had a C to A change in the second DR6 and the OWM rhesus macaque and African green monkey had a G to A change in the first DR6. All of the NWMs had a T to C change in the second DR6. In addition, the spider monkey had a G to T change in the second DR6. Functional analyses of these sites are underway to assess if these changes affect the binding of VDR to the sites and activation of the promoter. Conservation of vitamin D3 regulation in diurnal primates and not nocturnal mammals (mouse, rat, & dog) suggests that a diurnal lifestyle may have selected for the regulation of the antimicrobial peptides by the vitamin D system. To test this, we are examining the conservation of the VDRE in both diurnal (lemurs) and nocturnal (galagos and lorises) prosimians. We obtained the genomic sequence of the CAMP gene and its promoter for a nocturnal prosimian (Garnett's galago) from the NCBI trace archive. The SINE and the VDRE were absent from the promoter. Currently, we are cloning the promoter regions from the diurnal ring-tailed lemur and other nocturnal galagos or lorises to determine if conservation correlates with lifestyle. In summary, the data indicate that vitamin D3-mediated regulation of the antimicrobial peptides CAMP and DEFB4 is evolutionarily important for innate immunity in humans and other primates as opposed to non-primate mammals.

The Effects of Nocturnal Life on the Circadian Patterns of Sex Hormones in Young Healthy Men

Irregular meals (mainly the skipping of breakfast) and inadequate sleep has become prevalent in young people. However, there has been inadequate attention on the adverse effects of this nocturnal life. We observed the 24-hr patterns of sex hormones and other relative hormones in ten medical students, with the randomized cross-over design, on either a diurnal life or a nocturnal life. The subjects on a diurnal life ate three meals (07:00, 13:00 and 19:00) and slept from 22:30 to 06:30. Nocturnal life was designed by skipping their breakfast but consuming a lot (> 50% of their daily food intake) in the evening and at night, sleeping from 01:30 to 08:30 the next morning. After three weeks in the experimental life, the 24-hr plasma concentrations of testosterone, free testosterone, dihydrotestosterone (DHT), androstenedione, prolactin, estrone, luteinizing hormone, cortisol and sex hormone binding globulin (SHBG) were measured every three hours. Plasma free testosterone and prolactin decreased, but cortisol increased when subjects followed the nocturnal life. In the diurnal lifestyle group, circadian rhythms were observed in the androgens (testosterone, free testosterone, DHT, androstenedione), prolactin, cortisol and SHBG in the cosinor analysis; however, circadian rhythms were almost extinguished in the nocturnal lifestyle group. Since sex hormones play important roles in the normal physiological condition, the effects of these changes in hormone concentration and its circadian rhythm should be considered and studied intensively.

The effects of nocturnal life on endocrine circadian patterns in healthy adults

We observed the 24-hour patterns of endocrine in medical students who lived either a diurnal life or nocturnal life. Nocturnal life was designed by skipping their breakfast but consuming much (>50% of their daily food intake) in the evening and at night with the sleep from 0130 h to 0830 h the next morning. After 3 weeks in the experimental life, the 24-hour plasma concentrations of melatonin, leptin, glucose and insulin were measured every three hours. Both plasma melatonin and leptin showed peaks at 0300 h in the diurnal lifestyle group, and the night peaks decreased in the nocturnal lifestyle group. The changes in the patterns of melatonin and leptin were highly consistent with that of night-eating syndrome (NES). Plasma glucose increased after all meals in both groups. Its concentration maintained a high level in the nocturnal lifestyle group between midnight and early morning while insulin secretion decreased markedly during this period. Furthermore, the strong association between glucose and insulin in the diurnal lifestyle group after meals was damaged in the nocturnal lifestyle group. It was suggested that nocturnal life leads to the impairment of insulin response to glucose. Taking these results together, nocturnal life is likely to be one of the risk factors to health of modern people, including NES, obesity and diabetes.