Analysis of physiological variations of piperidine levels in tissues by mass fragmentography

By use of a mass fragmentographic technique the distribution of piperidine in tissues and changes in levels under physiological conditions were examined. Only trace amounts of piperidine existed in the brain of several animal species, although higher concentrations were detected in other species. In the brain of rats and rabbits, some regional differences were seen and high concentrations were found in the striatum. Piperidine levels in the brain and adrenal gland similarly showed the daily and seasonal rhythmic fluctuations.     

Evidence for species differences in the pattern of androgen receptor distribution in relation to species differences in an androgen-dependent behavior

Chickens (Gallus gallus domesticus) and Japanese quail (Coturnix japonica), two closely related gallinaceous bird species, exhibit a form of vocalization-crowing-which differs between the species in two components: its temporal acoustic pattern and its accompanying postural motor pattern. Previous work utilizing the quail-chick chimera technique demonstrated that the species-specific characteristics of the two crow components are determined by distinct brain structures: the midbrain confers the acoustic pattern, and the caudal hindbrain confers the postural pattern. Crowing is induced by androgens, acting directly on androgen receptors. As a strategy for identifying candidate neurons in the midbrain and caudal hindbrain that could be involved in crow production, we performed immunocytochemistry for androgen receptors in these brain regions in both species. We also investigated midbrain-to-hindbrain vocal-motor projections. In the midbrain, both species showed prominent androgen receptor immunoreactivity in the nucleus intercollicularis, as had been reported in previous studies. In the caudal hindbrain, we discovered characteristic species differences in the pattern of androgen receptor distribution. Chickens, but not quail, showed strong immunoreactivity in the tracheosyringeal division of the hypoglossal nucleus, whereas quail, but not chickens, possessed strong immunoreactivity in a region of the ventrolateral medulla. Some of these differences in hindbrain androgen receptor distribution may be related to the species differences in the postural component of crowing behavior. The results of the present study imply that the spatial distribution of receptor proteins can vary even between closely related species. Such variation in receptor distribution could underlie the evolution of species differences in behavior.     

HOW MAMMALS PRODUCE LARGE-BRAINED OFFSPRING

Two explanations for species differences in neonatal brain size in eutherian mammals relate the size of the brain at birth to maternal metabolic rate. Martin (1981, 1983) argued that maternal basal metabolic rate puts an upper bound on the mother's ability to supply energy to the fetus, thereby limiting neonatal brain size. Hofman (1983) proposed that gestation length in mammals is constrained by maternal metabolic rate, implying an indirect constraint on neonatal brain size. Since individuals of precocial species have much larger neonatal brain sizes and are gestated longer for a given maternal body size than individuals of altricial species, Martin's and Hofman's ideas also require that mothers of precocial offspring have higher metabolic rates for their body sizes than mothers of altricial offspring. Data on 116 mammal species from 13 orders show that neither neonatal brain size nor gestation length is correlated with maternal metabolic rate when maternal body-size effects are removed. For a given maternal size, there is no difference in metabolic rates between precocial and altricial species, despite a two-fold difference between them in average neonatal brain size. However, neonatal brain size is strongly correlated with gestation length and litter size, independently of maternal size and metabolic rate. Analyses conducted within orders replicated the findings for gestation length and suggested that neonatal brain size may be at best only weakly related to metabolic rate. Differences in neonatal brain size appear to have evolved primarily with species differences in gestation length and litter size but not with differences in metabolic rate; large-brained offspring are typically produced from litters of one that have been gestated for a long time relative to maternal size. We conclude that species differences in relative neonatal brain size reflect different life-history tactics rather than constraints imposed by metabolic rate.     

Evidence for species differences in the pattern of androgen receptor distribution in relation to species differences in an androgen‐dependent behavior

Chickens (Gallus gallus domesticus) and Japanese quail (Coturnix japonica), two closely related gallinaceous bird species, exhibit a form of vocalization—crowing—which differs between the species in two components: its temporal acoustic pattern and its accompanying postural motor pattern. Previous work utilizing the quail‐chick chimera technique demonstrated that the species‐specific characteristics of the two crow components are determined by distinct brain structures: the midbrain confers the acoustic pattern, and the caudal hindbrain confers the postural pattern. Crowing is induced by androgens, acting directly on androgen receptors. As a strategy for identifying candidate neurons in the midbrain and caudal hindbrain that could be involved in crow production, we performed immunocytochemistry for androgen receptors in these brain regions in both species. We also investigated midbrain‐to‐hindbrain vocal‐motor projections. In the midbrain, both species showed prominent androgen receptor immunoreactivity in the nucleus intercollicularis, as had been reported in previous studies. In the caudal hindbrain, we discovered characteristic species differences in the pattern of androgen receptor distribution. Chickens, but not quail, showed strong immunoreactivity in the tracheosyringeal division of the hypoglossal nucleus, whereas quail, but not chickens, possessed strong immunoreactivity in a region of the ventrolateral medulla. Some of these differences in hindbrain androgen receptor distribution may be related to the species differences in the postural component of crowing behavior. The results of the present study imply that the spatial distribution of receptor proteins can vary even between closely related species. Such variation in receptor distribution could underlie the evolution of species differences in behavior. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 203–220, 2002     

Substrate specificity of brain cholinesterase activity of evolutionary old species of fishes

An analysis of brain cholinesterase properties in 3 species of cartilaginous fishes and 1 species of chondrostei, was conducted for the first time. The skates brain enzymes, as to substrate specificity, are shown to be referred to acetylcholinesterases, and the shark brain cholinesterase - to atypical acetylcholinesterase. Kaluga brain cholinesterase, as to its substrate specificity, differes from brain enzymes of cartilaginous fishes. The differences in properties of the nervous tissue cholinestarase of the investigated fish species are the parameters of evolutionary divergence of species.     

Auditory stimulus-induced changes in immediate-early gene expression related to an inborn perceptual predisposition

Auditory-induced expression of the immediate-early gene ZENK was examined in 18 brain areas of domestic chicken and Japanese quail subjects with no previous exposure to parental vocalizations. After one 30-min exposure (approximately 120 calls) within 24 h of hatching to either the chicken or quail maternal call, paired subjects from each species showed significantly more intense levels of ZENK staining to conspecific (own species) calls. Single brain areas did not show consistent, large differences in ZENK expression across all subject pairs. Instead, a majority of brain areas exhibited a small conspecific stimulus-induced staining advantage in each species. The species differed in the quantitative distribution of ZENK responses among brain areas; qualitative patterns of call-induced staining exhibited both similarities and differences. The results suggest shared neural correlates and potential developmental/evolutionary differences in congenital brain responses to biologically significant auditory stimuli in na?ve individuals of the two species.     

Evidence for small scale variation in the vertebrate brain: mating strategy and sex affect brain size and structure in wild brown trout (Salmo trutta)

The basis for our knowledge of brain evolution in vertebrates rests heavily on empirical evidence from comparative studies at the species level. However, little is still known about the natural levels of variation and the evolutionary causes of differences in brain size and brain structure within‐species, even though selection at this level is an important initial generator of macroevolutionary patterns across species. Here, we examine how early life‐history decisions and sex are related to brain size and brain structure in wild populations using the existing natural variation in mating strategies among wild brown trout (Salmo trutta). By comparing the brains of precocious fish that remain in the river and sexually mature at a small size with those of migratory fish that migrate to the sea and sexually mature at a much larger size, we show, for the first time in any vertebrate, strong differences in relative brain size and brain structure across mating strategies. Precocious fish have larger brain size (when controlling for body size) but migratory fish have a larger cerebellum, the structure in charge of motor coordination. Moreover, we demonstrate sex‐specific differences in brain structure as female precocious fish have a larger brain than male precocious fish while males of both strategies have a larger telencephalon, the cognitive control centre, than females. The differences in brain size and structure across mating strategies and sexes thus suggest the possibility for fine scale adaptive evolution of the vertebrate brain in relation to different life histories.     

Species differences in structure-activity relationships of adenosine agonists and xanthine antagonists at brain A1 adenosine receptors

A series of 28 adenosine analogs and 17 xanthines has been assessed as inhibitors of binding of N6-R-[3H]phenylisopropyladenosine binding to A1 adenosine receptors in membranes from rat, calf, and guinea pig brain. Potencies of N6-alkyl- and N6-cycloalkyladenosines are similar in the different species. However, the presence of an aryl or heteroaryl moiety in the N6 substituent results in marked species differences with certain such analogs being about 30-fold more potent at receptors in calf than in guinea pig brain. Potencies at receptors in rat brain are intermediate. Conversely, 2-chloroadenosine and 5'-N-ethylcarboxamidoadenosine are about 10-fold less potent at receptors in calf brain than in guinea pig brain. Potencies of xanthines, such as theophylline, caffeine and 1,3-dipropylxanthine are similar in the different species. However, the presence of an 8-phenyl or 8-cycloalkyl substituent results in marked species differences. For example, a xanthine amine conjugate of 1,3-dipropyl-8-phenylxanthine is 9-fold more potent at receptors in calf than in rat brain and 110-fold more potent in calf than in guinea pig brain. Such differences indicate that brain A1 adenosine receptors are not identical in recognition sites for either agonists or antagonists in different mammalian species.     

以田鼠作为动物模型来研究社会行为的进化:基因、脑与行为

田鼠属的一些近缘种间具有独特的社会行为多态性。例如Microtusochrogaster和M .pinetorum为一夫一妻制 ,而M .montanus和M .pennsylvanicus则为独居和一夫多妻制。无论是在野外还是人工饲养的条件下 ,单配制的田鼠其雌、雄成年个体一经交配即在两者之间形成长期的配偶关系并且双亲共同哺育后代。已证明神经多肽加压素 (Vasopressin)参与了田鼠单配制行为的神经调控。本篇综述了过去以及近期关于加压素调控田鼠配偶关系形成的研究结果和进展。首先 ,阐述了加压素V1a受体 (V1aR)在脑分布的种间差异 ,并以此来鉴别特定脑区在配偶关系形成中的功能 ;其次 ,探讨了运用V1aR拮抗物的药理学方法来决定究竟哪些脑区参与配偶关系的形成 ,还描述了田鼠种间V1aR基因结构和功能的不同 ,以及这些不同对V1aR在大脑的分布和行为调控潜在的作用机制 ;最后 ,讨论了最新的研究结果 ,即对一夫多妻制田鼠进行脑V1aR基因的改造 ,从而使之表现出一夫一妻制田鼠的行为。总之 ,了解复杂的社会性行为的遗传和神经机制可以加深我们对种间和种内行为分歧进化的理解     

Brain organization mirrors caste differences,colony founding and nest architecture in paper wasps (Hymenoptera: Vespidae)

The cognitive challenges that social animals face depend on species differences in social organization and may affect mosaic brain evolution. We asked whether the relative size of functionally distinct brain regions corresponds to species differences in social behaviour among paper wasps (Hymenoptera: Vespidae). We measured the volumes of targeted brain regions in eight species of paper wasps. We found species variation in functionally distinct brain regions, which was especially strong in queens. Queens from species with open-comb nests had larger central processing regions dedicated to vision (mushroom body (MB) calyx collars) than those with enclosed nests. Queens from advanced eusocial species (swarm founders), who rely on pheromones in several contexts, had larger antennal lobes than primitively eusocial independent founders. Queens from species with morphologically distinct castes had augmented central processing regions dedicated to antennal input (MB lips) relative to caste monomorphic species. Intraspecific caste differences also varied with mode of colony founding. Independent-founding queens had larger MB collars than their workers. Conversely, workers in swarm-founding species with decentralized colony regulation had larger MB calyx collars and optic lobes than their queens. Our results suggest that brain organization is affected by evolutionary transitions in social interactions and is related to the environmental stimuli group members face.     

Distributed cognition and social brains: reductions in mushroom body investment accompanied the origins of sociality in wasps (Hymenoptera: Vespidae)

The social brain hypothesis assumes the evolution of social behaviour changes animals'' ecological environments, and predicts evolutionary shifts in social structure will be associated with changes in brain investment. Most social brain models to date assume social behaviour imposes additional cognitive challenges to animals, favouring the evolution of increased brain investment. Here, we present a modification of social brain models, which we term the distributed cognition hypothesis. Distributed cognition models assume group members can rely on social communication instead of individual cognition; these models predict reduced brain investment in social species. To test this hypothesis, we compared brain investment among 29 species of wasps (Vespidae family), including solitary species and social species with a wide range of social attributes (i.e. differences in colony size, mode of colony founding and degree of queen/worker caste differentiation). We compared species means of relative size of mushroom body (MB) calyces and the antennal to optic lobe ratio, as measures of brain investment in central processing and peripheral sensory processing, respectively. In support of distributed cognition predictions, and in contrast to patterns seen among vertebrates, MB investment decreased from solitary to social species. Among social species, differences in colony founding, colony size and caste differentiation were not associated with brain investment differences. Peripheral lobe investment did not covary with social structure. These patterns suggest the strongest changes in brain investment—a reduction in central processing brain regions—accompanied the evolutionary origins of eusociality in Vespidae.     

Ontogenetic development of the ophthalmic rete in relation to brain cooling in chickens and pigeons

The brain cooling capacity of the altricial pigeon increases during posthatching growth at a higher rate than that of the precocial duck and chicken. To determine if this difference between the altricial and the precocial modes of development can be related to growth rates of the vascular heat exchanger involved in brain cooling (the ophthalmic rete), we performed a morphometric analysis of this structure during the post-hatching maturation of the three species. The number of vascular units in the rete did not change during development but differed significantly among species. The retia continued to grow in length and diameter in an exponential relation with body mass at similar rates in all species. The surface area of the retial arteries, which reflects the area available for countercurrent heat exchange, also increased exponentially with body mass, but without significant differences among the three species. However, the effectiveness of the rete in brain cooling, as indicated by the degree of brain cooling per unit of heat-exchange area in the rete, was higher in the altricial pigeon than in the precocial chicken and duck. It is concluded that the posthatching morphometric changes in the ophthalmic rete (rete ophthalmicum) are important for the development of brain cooling capacity, but cannot solely explain differences in brain cooling between growing altricial and precocial birds. These differences are most likely related to differences in the maturation of the central thermoregulatory control system and the peripheral effector mechanisms among the two groups of birds.     

Noradrenaline, dopamine, 5-hydroxytryptamine and tryptophan concentrations in the brains of four cohabiting species of fish

1. The concentrations of the neurotransmitters noradrenaline, dopamine and 5-hydroxy-tryptamine and the amino acid tryptophan were determined in the telencephalon, optic lobes and rest of the brains of four species of fish collected from a stream in central Saskatchewan. 2. The species investigated were white sucker (Catostomus commersoni), longnose sucker (Catostomus catostomus), longnosed dace (Rhinichthys cataractae) and northern pike (Esox lucius). 3. Significant differences were found in the concentrations of amines in different regions of the brain within species and within the same brain region between species. 4. These results may be related to the phylogenetic differences or to patterns in brain development evolved by fish species to adapt to particular lifestyles.     

A potential role for differential contractility in early brain development and evolution

Differences in brain structure between species have long fascinated evolutionary biologists. Understanding how these differences arise requires knowing how they are generated in the embryo. Growing evidence in the field of evolutionary developmental biology (evo-devo) suggests that morphological differences between species result largely from changes in the spatiotemporal regulation of gene expression during development. Corresponding changes in functional cellular behaviors (morphogenetic mechanisms) are only beginning to be explored, however. Here we show that spatiotemporal patterns of tissue contractility are sufficient to explain differences in morphology of the early embryonic brain between disparate species. We found that enhancing cytoskeletal contraction in the embryonic chick brain with calyculin A alters the distribution of contractile proteins on the apical side of the neuroepithelium and changes relatively round cross-sections of the tubular brain into shapes resembling triangles, diamonds, and narrow slits. These perturbed shapes, as well as overall brain morphology, are remarkably similar to those of corresponding sections normally found in species such as zebrafish and Xenopus laevis (frog). Tissue staining revealed relatively strong concentration of F-actin at vertices of hyper-contracted cross-sections, and a finite element model shows that local contraction in these regions can convert circular sections into the observed shapes. Another model suggests that these variations in contractility depend on the initial geometry of the brain tube, as localized contraction may be needed to open the initially closed lumen in normal zebrafish and Xenopus brains, whereas this contractile machinery is not necessary in chick brains, which are already open when first created. We conclude that interspecies differences in cytoskeletal contraction may play a larger role in generating differences in morphology, and at much earlier developmental stages, in the brain than previously appreciated. This study is a step toward uncovering the underlying morphomechanical mechanisms that regulate how neural phenotypic differences arise between species.     

Oxidation of β-Phenylethylamine by Both Types of Monoamine Oxidase: Examination of Enzymes in Brain and Liver Mitochondria of Eight Species

Abstract: β-Phenylethylamine (PEA) was characterized as a substrate for type A and type B monoamine oxidase (MAO) in brain and liver mitochondria of eight species at different substrate concentrations. In all species, at 10.0 μM, PEA was almost specific for type B MAO. At 1000 μM, however, the amine was common for both types of MAO in rat brain and liver, human brain and liver, mouse brain, guinea pig brain and liver, and bovine brain, while it was specific for type B MAO in mouse liver, rabbit brain and liver, bovine liver, pig brain and liver, and chicken brain and liver. From the present study, when PEA is used as a type B substrate, it is recommended that the substrate concentration should be sufficiently low to avoid the effects of species and tissue differences.     

Quantifying habitat complexity in aquatic ecosystems

1. Many aquatic studies have attempted to relate biological features, such as species diversity, abundance, brain size and behaviour, to measures of habitat complexity. Previous measures of habitat complexity have ranged from simple, habitat‐specific variables, such as the number of twigs in a stream, to quantitative parameters of surface topography, such as rugosity. 2. We present a new video‐based technique, called optical intensity, for assaying habitat complexity in aquatic ecosystems. Optical intensity is a visual, quantitative technique modifiable for any scale or for a nested analysis. We field‐tested the technique in Lake Tanganyika, Tanzania, on 38 quadrats (5 × 5 m) to determine if three freshwater habitats (sand, rock and intermediate) were quantitatively different. 3. A comparison of the values obtained from optical intensity with a previous measure of surface topography (rugosity) showed that the two corresponded well and revealed clear differences among habitats. Both the new measure and rugosity were positively correlated with species diversity, species richness and abundance. Finally, whether used alone or in combination, both measures had predictive value for fish community parameters. 4. This new measure should prove useful to researchers exploring habitat complexity in both marine and freshwater systems.     

Bigger brains cycle faster before neurogenesis begins: a comparison of brain development between chickens and bobwhite quail

The chicken brain is more than twice as big as the bobwhite quail brain in adulthood. To determine how this species difference in brain size emerges during development, we examined whether differences in neurogenesis timing or cell cycle rates account for the disparity in brain size between chickens and quail. Specifically, we examined the timing of neural events (e.g. neurogenesis onset) from Nissl-stained sections of chicken and quail embryos. We estimated brain cell cycle rates using cumulative bromodeoxyuridine labelling in chickens and quail at embryonic day (ED) 2 and at ED5. We report that the timing of neural events is highly conserved between chickens and quail, once time is expressed as a percentage of overall incubation period. In absolute time, neurogenesis begins earlier in chickens than in quail. Therefore, neural event timing cannot account for the expansion of the chicken brain relative to the quail brain. Cell cycle rates are also similar between the two species at ED5. However, at ED2, before neurogenesis onset, brain cells cycle faster in chickens than in quail. These data indicate that chickens have a larger brain than bobwhite quail mainly because of species differences in cell cycle rates during early stages of embryonic development.     

Species Differences in the Brain Regional Distribution of Receptor Binding for Thyrotropin-Releasing Hormone

Abstract: A survey of the regional distribution of binding of 1 nM [³H](3-MeHis²)thyrotropin-releasing hormone ([³H]MeTRH) to TRH receptors in the brains of eight mammalian species revealed major species differences in both the absolute and relative values of TRH receptor binding in different brain regions. Several brain regions exhibited binding equal to or exceeding that in the anterior pituitary gland of the same species, including the amygdaia in the guinea pig and rat, the hypothalamus in the guinea pig, the nucleus accumbens in the rabbit, and all these and other regions in the cat and dog, for which pituitary binding was exceptionally low. Species could be divided into two groups according to which brain region appeared highest in binding: rabbits, sheep, and cattle had highest binding in the nucleus accumbens/septal area, whereas guinea pigs, rats, dogs, cats, and pigs had highest binding in the amygdala/temporal cortex area. The nucleus accumbens consistently exceeded the caudate-putamen in receptor binding. For most brain regions, rabbits, rodents, and sheep tended to be higher than carnivores, cattle, or pigs. Further regions that exhibited appreciable binding in most species included the olfactory bulb and tubercle, hippocampus, and various cortical and brain stem areas. In fact, essentially all brain regions appeared to have detectable levels of TRH receptors in at least some species, but no rat peripheral tissues have yet shown detectable receptor binding. The species differences appeared to reflect largely if not entirely differences in receptor density, although this was not tested in every species.     

Conservation of regional gene expression in mouse and human brain

Many neurodegenerative diseases have a hallmark regional and cellular pathology. Gene expression analysis of healthy tissues may provide clues to the differences that distinguish resistant and sensitive tissues and cell types. Comparative analysis of gene expression in healthy mouse and human brain provides a framework to explore the ability of mice to model diseases of the human brain. It may also aid in understanding brain evolution and the basis for higher order cognitive abilities. Here we compare gene expression profiles of human motor cortex, caudate nucleus, and cerebellum to one another and identify genes that are more highly expressed in one region relative to another. We separately perform identical analysis on corresponding brain regions from mice. Within each species, we find that the different brain regions have distinctly different expression profiles. Contrasting between the two species shows that regionally enriched genes in one species are generally regionally enriched genes in the other species. Thus, even when considering thousands of genes, the expression ratios in two regions from one species are significantly correlated with expression ratios in the other species. Finally, genes whose expression is higher in one area of the brain relative to the other areas, in other words genes with patterned expression, tend to have greater conservation of nucleotide sequence than more widely expressed genes. Together these observations suggest that region-specific genes have been conserved in the mammalian brain at both the sequence and gene expression levels. Given the general similarity between patterns of gene expression in healthy human and mouse brains, we believe it is reasonable to expect a high degree of concordance between microarray phenotypes of human neurodegenerative diseases and their mouse models. Finally, these data on very divergent species provide context for studies in more closely related species that address questions such as the origins of cognitive differences.     

Relative brain size and ecology in birds

We test the hypothesis that the relative sizes of the different parts of the brain (brain stem, optic lobes, cerebellum and cerebral hemispheres), measured after body size effects have been removed, are associated with differences in behaviour and ecology across bird species.
The results demonstrate that behavioural and ecological correlates of relative brain size are not independent of each other. When the effects of variation in other categories are accounted for, the strongest single effect is due to relatively large brain sizes being associated with altricial development. It is unlikely that this effect is due to the confounding influence of taxonomic associations.
Overall, the results do not provide support for the idea that differences in measures of environmental complexity select for differences in relative brain size.