Vertebrate Phylogeny Research Articles

Physiological evolution of the renin-angiotensin system.

The renin-angiotensin system (RAS) in mammals may participate in the controls of blood pressure and aldosterone secretion, and possibly in the regulation of renal function. It has been shown that renin release is controlled by:1) two intrarenal receptors, the renal arteriolar receptor and the macula densa; 2) the sympathetic nervous system; and 3) several humoral agents. Recent studies indicate interrelations between the RAS and renal prostaglandins and the kallikrein-kinin system. Comparative studies have revealed that renal renin and the juxtaglomerular (JG) cells emerged during the early evolution of bony fishes, wherease the macula densa evolved later in the vertebrate phylogney. Exogenously administered angiotensins and renin produce vasopressor actions in representative species of all vertebrate classes from elasmobranchs to mammals, and increase secreations of mineralocorticoids from the adrenal cortex (interrenal) in amphibians, repitles, and possibly in teleosts. Angiotensin causes glomerular diuresis in teleosts and lung-fishes, which may be ascribed to increased dorsal aortic pressure, while angiotensin may have both glomerular and tubular actions in some amphibians. Intracranial injection of angiotensin stimulates drinking in teleosts, repites, and birds, but not in amphibians. Hemorrage and acute hypotension are potent stimuli for causing renin release in an aglomerular teleost and a bird. When we consider this fact together with the anatomical evidence that the evolution of the JG cells precedes that of the macula densa, it appears that the RAS HAS EVOLVED WITH A CLOSE RELATIONSHIP TO BLOOD PRESSURE HOEMOSTASIS. On the other hand, there is no clear evidence that the RAS is activated in depleted teleosts and amphibians. Although the RAS appears to exert several functions in man and other mammals, some of them may be more important in primitive animals, while a similar function remains in mammals as a relic of the primitive system. Comparative approaches provide a perspective of biological history and unique experimental model that will eventually aid in understanding of the underlying mechanisms operating in mammals.

On the diversity of sperm histones in the vertebrates. III. Electrophoretic variability of testis‐specific histone patterns in Anura contrasts with relative constancy in Squamata

AbstractA starch gel electrophoretic survey of testis‐specific histones in frogs, snakes and lizards reveals a multiple banded pattern in most of these vertebrates whether the proteins are extracted from the testis cell suspension of a single animal or from chromatin pooled from the testes of several animals. Hence, the multiple banded pattern is probably typical for each individual in a particular species. When such testis‐specific histones of Anura are compared with those of Squamata, a notable difference emerges. Thus, the principal Xenopus, Bufo and Rana testicular proteins show entirely different patterns from each other upon starch gel electrophoresis while in Squamata, each of the species examined shows a similar 2‐banded pattern in the protamine region of the electrophoretogram. In the anurans Xenopus and Scaphiopus, the testis‐specific histone patterns are different even amongst several congeneric species. Although the present survey examines only a limited number of species, the electrophoretic data do point to the order Squamata as one place in vertebrate phylogeny where the diversity of testis‐specific histones in fish and amphibians appears to give way to a relative constancy of such proteins in reptiles. Such an evolutionary trend may be consistent with a modified version of Bloch's ('69) hypothesis that relates sperm histone variability to genetically based sex determination.

Evolution of Active Neurohypophysial Principles Among the Vertebrates

Nine active neurohypophysial peptides have been identified among the vertebrates. Arginine-vasotocin appears to be the most primitive. It occurs in cyclostomes and among representative species from all major branches of vertebrate phylogeny. The eight other neurohypophysial principles are presumed to have evolved from arginine-vasotocin after one or more reduplications of the primitive arginine-vasotocin gene. Argininevasotocin cannot be detected in the adult mammalian neurohypophysis but it has been found in the pineal and subcommissural organs of adult mammals. Arginine-vasotocin may be released into the cerebrospinal fluid and influence functions mediated by hypothalamic hypophysiotropic factors. The primitive functions of arginine-vasotocin are not clear. They may relate to cardiovascular regulation since vascular responses to arginine-vasotocin can be demonstrated in species representing all major branches of vertebrate evolution.

Esquisse de l'evolution des hormones gonadotropes et thyreotropes des vertébrés

Results from comparative endocrinology, from structural studies on mammalian hormones, and classical data of vertebrate phylogeny have been used to outline the evolution of thyrotropic (TSH) and gonadotropic (GTH) hormones. The main hypotheses are as follows. A common ancestral molecule gave rise, by genic duplication, to two subunits α and β. The first hormone (α-β) was gonadotropic but later had both functions (TSH and GTH). Duplication of β then gave rise to β 1 (with gonadotropic, LH-type, potentialities) and β 2 (with thyrotropic potentialities). Finally the FSH β-type subunit originated later from a duplication of β 2. Along these lines, hormonal specializations and diversifications occurred, due to genic modifications and associated structural changes in both α and β subunits.

Phylogeny of Lymphocyte Structure and Function

Data from mammalian systems on the molecular basis of immune recognition, on the structural and functional heterogeneity of lymphocytes, and on the interactions between lymphocytes have provided guidelines for examining the lymphocyte from a phylogenetic perspective. Current information indicates that regardless of the variability of organized lymphoid tissues and the sometimes subtle diversity of immune responses in evolutionarily distant forms, the small lymphocyte has been maintained both morphologically and as an effector of immune reactivities throughout vertebrate phylogeny. Moreover, the basic properties of the mammalian lymphocytes—the discriminatory recognition of nonself plus the amplification steps that follow such a recognition event appear to be common to lymphocytes from all vertebrates. Although examples of lymphocyte heterogeneity and cellular cooperation have been reported for representative elasmobranchs, teleosts, and amphibians, the extent and nature of lymphocyte diversity remain as major unsolved problems currently being investigated by immunologists.

Corticalization of two divisions of the visual system during vertebrate evolution

Data on the evolution of the visual system in vertebrate phylogeny are described. Visual projections are demonstrated in the telencephalon of cyclostomata (lampreys). The existence of a retino-thalamo-telencephalic pathway is demonstrated in elasmobranchs (skates). Two visual pathways are present in amphibians (frogs) and reptiles (turtles): retino-thalamo-telencephalic and retino-tecto-thalamo-telencephalic, and these overlap partly at the thalamic level in the lateral geniculate nucleus and completely in the telencephalon. In turtles the earliest visual and tectal impulses relay on their way to the telencephalon in the lateral geniculate body, and later impulses relay in the nucleus rotundus. In mammals (rats) visual tecto-cortical connections are seen; judging from the latent period of potentials arising in the visual cortex in response to stimulation of the superior colliculi these connections have one synaptic relay in the thalamus. The much shorter latent periods of visual evoked potentials recorded in the tectum of the monkey than in turtles (under identical chronic experimental conditions) confirm the views of morphologists on the progressive development of the tectal division of the visual system in vertebrate phylogeny. It is concluded that corticalization of both divisions of the visual system, i.e., the existence of telencephalic representation, appears in the early stages of vertebrate evolution.

Electrophysiological investigation of tecto-thalamo-telencephalic relations in frogs

Projections of the tectum mesencephali to the thalamus and telencephalon were investigated inRana temporaria. Individual cells in the optic neuropil of the lateral zone of the thalamus (corpus geniculatum thalami, n. Bellonci) and n. geniculatus lateralis respond to stimulation of the tectum mesencephali and to flashes but not to somatic stimuli. Many of the tectally reactive neurons in the medio-central zone of the thalamus, including n.postero-centralis, n.postero-lateralis, and n.rotundus, and in the telencephalon (the primordium of the hippocampus and septum) are convergent for somatic and visual impulses. The character of the macroresponses and spike responses to stimulation of the tectum mesencephali is the same for both zones of the thalamus. Tetanization within the lateral zone of the thalamus inhibits the conduction of visual and tectal impulses to the telencephalon, whereas during tetanization of the medio-central zone only the later components of visual and tectal evoked potentials of the telencephalon are suppressed. Responses with shorter latency than to stimulation of the medio-central zone arise in the telencephalon (primordium of the hippocampus) in response to electrical stimulation of the lateral zone by single pulses. In frogs the two divisions of the visual system — thalamo-telencephalic and tecto-thalamo-telencephalic — thus overlap considerably at the level of the thalamus and completely at the telencephalic level. In vertebrate phylogeny there is a progressive demarcation and specialization of these two visual channels.

Formation of the structural and functional organization of the paleo-, archi- and neocortex in premammalian phylogeny.

The following general conclusions are drawn from the results of electrophysiological and neuromorphologieal investigations conducted on cyclostomes, amphibians and r ep tiles. 1. Three formations of the endbrain (paleophallium, archipallium and neopallium), starting from the early stages of vertebrate evolution, appear and develop under the p r e s sure of three sources of afferent supply: the olfactory system, the paleoand neohypothalamus and the nuclear structures of the dorsal thalamus. These relationships are established in accordance with a definite principle: the phylogenetically old structures of the endbrain are elaborated mainly upon old formations and the new brain structures upon new. 2. Corticalization of the central nervous system follows the principle of development from diffuse structural and fimctional organization to more discrete, specialized forms of nervous activity. Orbeli (1, 2), a founder of evolutionary physiology, emphasized that the main task of this new discipline is to explain not only the pattern of formation of part icular functions or functional systems in the course of evolution of the animal world, but also to discover causal relationships and the significance of factors which determine the course of the evolutionary process. At the same time, it should predict the pathways and trends of future evolutionary transformations in structure and function of the brain. These fundamental ideas expounded by Orbeli led to electrophysiological, conditioned-reflex and neuromorphological investigations or representat ives of the Acrania, Cyclosto~ and Plagiostom fishes, amphibians, repti les and lower mammals (3, 4). A number of generalizations were made on the functional evolution both of the brain as a whole and on its individual systems of integration: cerebellocortical , thalamocortical, and hypothalamocortical. The following conclusions have been drawn: first , the principle of development by stages of the nervous system, according to which a shift of functions is observed in the central nervous system at ascending stages of vertebrate phylogeny; second, in the process of corticalization, and encephalization there is a tendency for development from diffuse, less, specialized forms of neural function to discrete , specialized forms. My subsequent researches into the structural and functional organization of the cerebel lotelencephalic and diencephalo-telencephalic levels of integration led logically to the problem of origin and the development of the highest level of integration, namely the cerebral cortex and, in particular, the neocortex. Currently, this problem is of great strategic importance and since the second half of the last century, contradictory views have been expressed about it (5-7). Since the endbrain in premammals receives p re dominantly olfactory afferents, the g~nesis of the neocortex has been correlated with the

Current Problems of Lower Vertebrate Phylogeny. Proceedings of the Fourth Nobel Symposium Held in June 1967 at the Swedish Museum of Natural History (Naturhistoriska riksmuseet) in Stockholm.Tor Orvig

<i>Current Problems of Lower Vertebrate Phylogeny. Proceedings of the Fourth Nobel Symposium Held in June 1967 at the Swedish Museum of Natural History (Naturhistoriska riksmuseet) in Stockholm.</i>Tor Orvig

A comparative study of vertebrate esterase multiplicity

1. 1. The properties of the multiple enzyme forms of soluble esterase activity have been studied in three non-mammalian species—lizard, frog and catfish. 2. 2. The resultant data has enabled a review and classification of esterase heterogeneity over a representative range of vertebrate phylogeny. 3. 3. Four main classes of esterase activity have been characterized (carboxyl-esterases, arylesterases, acetylesterases and cholinesterases), but evidence for further differentiation of activity-types within these groups is also presented. 4. 4. Considerable molecular variation is evident between species and a late evolutionary development of some esterase types (e.g. acetylesterases, group I carboxylesterases and cholinesterases) seems indicated.

On the Evolution of the Integrative Activity of the Central Nervous System in the Phylogeny of Vertebrates

This chapter analyzes the functional and structural organization of some parts of the central nervous system, in a series of animals constituting the basic stages of the evolution, which is acrania, cyclostomata, crosstomata, reptiles, and lower mammals. In amphyoxus lunceolutus , the responses to light or electrical stimulation of both the head and the tail of the nervous tube were of the same intensity. These reactions persisted even after surgical disconnection of the nervous tube. Combination of unconditioned and conditioned stimulation of the disconnected parts of the head and tail end of amphyoxus resulted in the formation of temporary connections. This proves that the central nervous system of amphyoxus is diffuse with no functional localization. In Cyclostomata, despite differentiation and formation of various parts of the central nervous system, the elements of diffuseness are still inherent. The experiments performed on reptiles ( varanus griseus ) demonstrated that stimulation of the dorsal thalamus evokes recruiting responses in the anterior and medial parts of the common and hippocampal cortex with a latency of 8–30 msec. The experiments carried out on rats and cats showed that low-frequency stimulation of nonspecific thalamic nuclei evokes responses in different cortical areas, different in their latency and the degree of recruiting.

Nachtrag zur “Wurmtheorie” der Vertebraten-Evolution

This paper presents some new arguments for the metameric-wonn-theory for the evolution of the Vertebrates (Gutmann 1966a). Metameric coelomoducts in Enteropneust larvae (Goodrich 1947) which should be interpreted as metanephridia show that the Enteropneusts can be derived from metameric Chordate-like predecessors. The myomeres of Branchiostoma are no solid organs as there exist sclerocoels. These must be interpreted as vestigial coelomic cavities. They can be cited as a proof for the metameric worm-theory. They function as a canal system, which gathers excretory stuff in the myomeres which these organs could otherwise not get rid of. The coelom-cavities are cleaned by the protonephridia in the gill region. Some additional details of the phylogenetic transformation of metameric coelom cavities into myomeres are reconstructed. It is shown that the problem of coelomic and myomeric metamerism cannot be solved in the way proposed in the literature concerned with this question. The metameric-worm-theory for the evolution of the Vertebrates pretends that metameric metanephridia were fused on the lower level of Vertebrate phylogeny and formed the archinephric ducts. A paper of Goodrich (1947) shows that there are similar cases of fused metanephridia in some Annelids. These are parallels to the postulated formation of the metanephridia in the lowest Vertebrates. The archinephric duct acquired its muscular coat when it was formed by fusion of metanephridia in the bodywall. Muscles of the body wall took over a new function by making peristaltic movements of the newly formed archinephric ducts possible. When the archinephric duct was moved back into the coelom it did not lose the still functioning muscular coat.

Hormones and endocrine glands of fishes. Studies of fish endocrinology reveal major physiologic and evolutionary problems.

The structures discussed above illustrate some of the evolutionary knowledge to be obtained from studies of the comparative biology of the endocrine system among the fishes (see also 17, 78). The interrenal (adrenocortical) gland is an example of an endocrine structure which shows great morphologic variation in the vertebrate series, and among the fishes themselves. The structural variability implies little selective value for any particular pattern, and, in fact, biochemically the interrenal tissue would seem to be involved in much the same kind of steroidogenesis in the vertebrates generally. However, the hormone aldosterone may be a tetrapod novelty. The caudal neurosecretory system is a good example of a ubiquitous endocrine apparatus, among at least teleostean and elasmo-branch fishes, for which a function has yet to be elucidated and which continues to challenge the comparative physiologist. This system, along with the Stannius corpuscles, is lacking in the tetrapods. The existence of these structures makes it clear that the endocrine biology of fishes cannot be tacitly summarized as being essentially similar to that of the tetrapods, only less well developed. The prolactin situation illustrates the existence of a gland-the pituitary-present among fishes as among tetrapods, which secretes a product only partly related to the tetrapod hormone and having a very different functional significance. In this case it is clear that "the hormone and the uses to which it is put" have undergone evolutionary change during vertebrate phylogeny.

Comparative Anatomy of Olfactory Centres and Tracts

Publisher Summary This chapter presents a survey of the comparative anatomy of the parts of the telencephalon that are entirely or predominantly related to the sense of smell. The structures included in this so-called “rhinencephalo” display a great variety in proportionate size and degree of differentiation, but nevertheless it is possible to recognize a common structural plan that underlies the morphology of this brain part in all groups of vertebrates. The central olfactory system of the various groups of submammalian vertebrates has been discussed. Attention is drawn first to the marked variations in development of the olfactory centres. It seems probable that the early vertebrates were endowed with a well developed olfactory apparatus, and that this macrosmatic condition has been maintained in the main line of vertebrate evolution. A fargoing regression of the olfactory apparatus and its centers has occurred at least 3 times in the course of phylogeny of the submammalian vertebrates, namely in the teleosts (Mormyridae), in the lizards (Chameleon, Anolis), and in birds. In all vertebrates, the primary olfactory elements are represented by neurosensory cells situated in the nasal epithelium. These elements are provided with extremely fine, unmyelinated axonal offshoots that convey the olfactory impulses to the bulbi.

Taste theories and the chemical stimulation of single papillae.

ArticleTaste theories and the chemical stimulation of single papillae.G Von BékésyG Von BékésyPublished Online:01 Jan 1966https://doi.org/10.1152/jappl.1966.21.1.1MoreSectionsPDF (3 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEncoding Taste: From Receptors to Perception19 November 2021Electric Taste30 June 2018Problems of Taste Specificity27 May 2008Gustatory neuron types in the peripheryPhysiology & Behavior, Vol. 69, No. 1-2Dysarthria and lacunar stroke1 November 1996 | Neurology, Vol. 47, No. 5The role of the human senses in food acceptanceElectrophysiology of taste and smell22 January 2001 | Clinical Physics and Physiological Measurement, Vol. 10, No. 2Binding proteins for sweet compounds from gustatory papillae of the cow, pig and ratBiochimica et Biophysica Acta (BBA) - General Subjects, Vol. 967, No. 1Physiology of the Sweet TasteSalt-acid confusion on the single fungiform papilla: Effect of changing acid sensitivityPhysiology & Behavior, Vol. 36, No. 6Taste and Olfaction: Sensory Discrimination1 January 2011Fine structure of taste buds in te human fungiform papillaEuropean Journal of Oral Sciences, Vol. 89, No. 4Gustatory reaction time in human adultsPhysiology & Behavior, Vol. 26, No. 4An Examination of Intertrial Interval and Gender Influences on Sucrose Detection Thresholds Established by a Modified Staircase Procedure25 June 2016 | Perception, Vol. 10, No. 1Human Taste: Response and Taste Bud Number in Fungiform PapillaeScience, Vol. 209, No. 4458Location and variation in number of taste buds in human fungiform papillaeEuropean Journal of Oral Sciences, Vol. 87, No. 6Psychophysical exponents for single papillae: A comparison with whole-mouth exponentsPerception & Psychophysics, Vol. 25, No. 6Taste acuity of the human palate: III. Studies with taste solutions on subjects in different age groups2 July 2009 | Acta Odontologica Scandinavica, Vol. 37, No. 4Physiologie Générale Du Goût8 July 2009 | Acta Oto-Laryngologica, Vol. 87, No. 3-6Taste Profiles from Single Human Taste Papillae6 October 2016 | Perceptual and Motor Skills, Vol. 47, No. 1Gustatory SystemHISTORY OF TASTE RESEARCHBIOPHYSICS AND CHEMISTRY OF TASTETHE VERTEBRATE PHYLOGENY, NEURAL CODE, AND INTEGRATIVE PROCESSES OF TASTEPSYCHOLOGICAL DIMENSIONS AND PERCEPTUAL ANALYSES OF TASTEMultiple sensitivity to chemical stimuli in single human taste papillaePhysiology & Behavior, Vol. 14, No. 6Taste ReceptorsZur Morphologie der Papilla fungiformis einiger NagetiereZur Physiologie des Geruchs- und GeschmackssinnesArchives of Oto-Rhino-Laryngology, Vol. 210, No. 1Can Taste Neuron Specificity Coexist with Multiple Sensitivity?Taste adaptation: the case of the wandering zero28 June 2007 | International Journal of Food Science & Technology, Vol. 9, No. 1Human taste response as a function of locus of stimulation on the tongue and soft palatePerception & Psychophysics, Vol. 16, No. 1Taste Specificity for Chemical Stimulation of Single Papillae, toward an Explanation of Disparate Results6 October 2016 | Perceptual and Motor Skills, Vol. 37, No. 2The Use of Vertebrate Laboratory Animals in Research on TasteA model of neural code for taste qualityPhysiology & Behavior, Vol. 9, No. 4The Interstimulus Interval for Taste: 1. The Efficiency of Expectoration and Mouthrinsing in Clearing the Mouth of Salt Residuals25 June 2016 | Perception, Vol. 1, No. 2Human taste perceptionC R C Critical Reviews in Food Technology, Vol. 3, No. 1A Fifth Modality of TasteActa Physiologica Scandinavica, Vol. 82, No. 4Chemosensory StimulationUltrastructure of Taste ReceptorsTaste PsychophysicsCharacterization and interaction of taste responses in chorda tympani fibers of the catBrain Research, Vol. 15, No. 2Central Issues Concerning the Nervous PeripheryMacromolecules and Brain Function — A 1969 BaedekerVenentonus, Haut- und Muskeldurchblutung an Unterarm und Hand bei BeinarbeitPfl�gers Archiv European Journal of Physiology, Vol. 309, No. 2Adaptation and cross-adaptation of the four gustatory qualitiesPerception & Psychophysics, Vol. 4, No. 6Psychophysik des elektrischen geschmacks: Qualit�ts- und intensit�tsbeziehungenArchiv f�r Klinische und Experimentelle Ohren- Nasen- und Kehlkopfheilkunde, Vol. 192, No. 3Variability in gustatory quality identificationPerception & Psychophysics, Vol. 2, No. 11Gustatory quality changes as a function of solution concentrationPerception & Psychophysics, Vol. 2, No. 1Chemically evoked sensations from single human taste papillaePhysiology & Behavior, Vol. 1, No. 3-4 More from this issue > Volume 21Issue 1January 1966Pages 1-9 https://doi.org/10.1152/jappl.1966.21.1.1PubMed5903911History Published online 1 January 1966 Published in print 1 January 1966 Metrics

A CRYSTALLOGRAPHIC STUDY OF VERTEBRATE OTOLITHS

1. The crystallographic properties of otoliths from 58 vertebrate species were investigated by means of polarization microscopy and x-ray diffraction.2. The otoliths occur as statoconia, microstatoliths, and statoliths. Usually only one kind is present in the labyrinth but in some vertebrates a combination of two or all three types may be found.3. While statoliths and microstatoliths always are polycrystalline, statoconia may either be polycrystalline or single crystals.4. Five different minerals, viz., apatite, calcite, aragonite, vaterite and calcium carbonate monohydrate, compose the endogenous otoliths in the vertebrate labycarbonate monohydrate, compose the endogenous otoliths in the vertebrate labyrinth. Some elasmobranchs have in addition exogenous statoconia consisting of sea-sand.5. The distribution of statoliths and/or statoconia, their texture and their composition within the vertebrate series, show remarkable consistencies; within each class the same kind of static bodies is usually present.6. Some crystallographic and biological aspects are discussed and it is suggested that the findings may be of some value for the study of the phylogeny of vertebrates and also may aid towards a better understanding of the function of the otolith organ.

Evolution and Phylogeny in Morphologically Uniform Groups

The general principles of phylogeny used today by workers in all areas of zoology and botany were developed over many years beginning in 1859, but also having a strong foundation in pre-Darwinian comparative anatomy and taxonomy. The major contribution to these principles was made before 1900, before the mechanisms of genetics and of population phenomena were known. Moreover, these principles were established on the basis of comparative studies of groups, both fossil and living, exhibiting large morphological divergence; this basis was formed largely by the work of the classical comparative anatomists who concentrated on heterogeneous groups, such as the mammals and the reptiles, or on differences of the magnitude seen between vertebrate and invertebrate classes and orders, and by the work of paleontologists also working mainly with heterogeneous groups and differences of ordinal or higher taxonomic levels. The principles of phylogeny are well formulated and have been excellently applied as shown by the great advance in our understanding of vertebrate phylogeny. We have a very clear picture of the phylogeny of the vertebrate classes and of the orders and even families in some groups such as the mammals and reptiles. Relationships within the invertebrate phyla are also well known although the issue of the phylogeny of the animal phyla is still open. Yet in my considerations of avian phylogeny and classification, I have come back repeatedly to the same pair of related questions: Are the general principles of phylogeny applicable to morphologically uniform groups (= uniform organization) such as the birds? and; Does the degree of uniformity of a group influence the formulation of general principles of phylogeny? There does seem to be a basis for these questions if for no other reasons then that morphologically uniform groups have been shunned by students of comparative anatomy and that the phylogeny of such groups, for example, birds, are poorly understood in spite of their anatomy being reasonably well known. Recently many workers claimed that progress in avian classification has been slow because of a lack of sufficient anatomical studies. The solution, they argue, is simply more anatomical studies. Yet this belief does not seem reasonable. The work of the earlier avian anatomists, summarized by FUrbringer, Gadow and Beddard, is very extensive and has been expanded by recent workers (Fisher, 1955). Nor

Theaaction of neurohypophysial and adrenocortical hormones on sodium balance in the cyclostome, Lampetra fluviatilis

The effect of neurohypophysial and adrenocortical hormones on the rate of net sodium loss from the lamprey ( Lampetra fluviatilis) was investigated. Neurohypophysial hormones increased the rate of sodium loss. Oxytocin on a unit weight basis was approximately five times as effective as Pitressin, arginine vasotocin or 3-valine oxytocin. The oxytocin-like polypeptide present in teleost neurohypophyses also increased the rate of sodium loss. Aldosterone and ACTH decreased the rate of sodium loss. The aldosterone blocking agent SC 11927 increased it. Cortisol had no effect. The results are discussed in relation to the electrolyte metabolism of lampreys and to vertebrate phylogeny generally.

ADAPTATIONS FOR BIPEDAL LOCOMOTION OF LIZARDS

In the course of vertebrate history, four rather distinct types of bipedalism have evolved: (1) the reptilian method (thecodonts, dinosaurs, lizards) in which the body is balanced more or less horizontally over the legs and the tail acts as a cantilever; (2) the avian method in which, with obvious exceptions, the body is balanced horizontal? ly over the legs and the center of gravity is directly over the hindlimbs; (3) the primate-human method in which the body is balanced semi-vertically or vertically over the limbs; and (4) the ricochetal method of saltatorial mammals in which the body is also balanced semi-vertically and the highly modified hindlegs are used simultaneously in repetitive jumping. Bipedal locomotion has thus evolved independently at least six times in vertebrate phylogeny; twice in reptiles (thecodont-dinosaur group, lizards), once in birds, and three times in mammals (marsupial ricochet, placental ricochet, primate alternating gait). It is of course recognized that several other kinds of mammals can attain a degree of bipedal? ism for short periods, but in none of them is the position maintained, nor the gait habitually used. With the exception of several species of lizards (Snyder, 1952), most birds, and man, no other living vertebrate regularly progresses at the bipedal two-time gait. As Howell (1944) has pointed out, the bipedal walk and run has, except for birds, developed from quadrupedal methods of loco? motion and he has briefly discussed some

Antidiuretic hormones.

There are at least 3 antidiuretic hormones. Arginine vasopressin is the antidiuretic hormone of most mammals, including man. This function is served by lysine vasopressin in the pig, and by arginine vasotocin in birds, reptiles and amphibians. All 3 hormones are closely related chemically and act on the kidney in a similar manner. Arginine vasotocin also exists in fish, in which the antidiuretic response is not known to occur. This antidiuretic hormone appeared, therefore, in vertebrate phylogeny before it acquired antidiuretic function. Anatomic considerations suggest that the fish neurohypophysis serves to regulate adenohypophysial secretion. There is evidence that such a primitive type of neurohypophysial function has persisted throughout subsequent vertebrate evolution.