Comparative analysis of calcium-binding protein-immunoreactive neuronal populations in the auditory and visual systems of the bottlenose dolphin (Tursiops truncatus) and the macaque monkey (Macaca fascicularis)

This study compares the distribution of three calcium-binding protein-immunoreactive (CaBP-immunoreactive) neuronal populations (calretinin-, calbindin- and parvalbumin-immunoreactive) in the visual and auditory systems in two mammalian species which are fundamentally different in their evolutionary traits and ecology, the aquatic toothed whale Tursiops truncatus (bottlenose dolphin) and the terrestrial Old World primate, Macaca fascicularis (long-tailed macaque). Immunocytochemical analyses, combined with computerized morphometry revealed that in the visual and auditory systems of the bottlenose dolphin, calretinin and calbindin are the prevalent calcium-binding proteins, whereas parvalbumin is present in very few neurons. The prevalence of calretinin and calbindin-immunoreactive neurons is especially obvious in the auditory system of this species. In both auditory and visual systems of the macaque monkey, the parvalbumin-immunoreactive neurons are present in comparable or higher densities than the calretinin and calbindin-immunoreactive neurons. In some structures of the visual and auditory systems of the macaque monkey, the calretinin- and calbindin-immunoreactive neurons are nearly absent. The prevalence of parvalbumin-immunoreactive over calretinin- and calbindin-immunoreactive neurons is particularly prominent in the visual system of primates. Thus, the dominant sensory systems in both aquatic and terrestrial mammals are enriched in specific phenotypes of calcium-binding protein-immunoreactive neurons.     

Auditory brainstem response in tammar wallaby (Macropus eugenii)

Auditory brainstem responses (ABR) elicited by click and tonal stimuli were recorded from the tammar wallaby (Macropus eugenii), a marsupial mammal. The morphology, threshold, amplitude, and latency of ABRs recorded in the tammar wallaby are similar to those of other marsupials and mammals used in auditory research, including humans. Thresholds determined by an algorithm employing cross-correlation and by conventional visual detection methods were comparable. The findings from this study indicate that tammar wallaby is a suitable model for auditory research and that algorithms employing cross-correlation are useful for detection of the ABR waveform.     

Hearing in the elephant (Elephas maximus): Absolute sensitivity, frequency discrimination, and sound localization.

Tested a young female Indian elephant to determine sensitivity and frequency-discrimination and sound-localization thresholds. S was found to have an audibility curve similar to that of other mammals but one that was more sensitive to low frequencies and less sensitive to high frequencies than any other mammalian audiogram, including human's. S's sensitivity to frequency differences at low frequencies equaled that of humans. S was accurate at localizing sounds in the azimuthal plane, with thresholds around 1° for broadband noise. S's ability to localize pure tones suggested that it could use both binaural time- and intensity-difference cues to localize sound. (62 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clinical trial of an oral vestibular shield for the control of snoring

1. Comparative aspects of iodine conservation in mammals were studied on the basis of published data on kidney and thyroid weights and function. 2. Very small mammals possessed an efficient reabsorption of iodide to compensate for the high glomerular filtration rate (GFR). 3. Humans and mammals of a similar and larger size had "lost" the ability to reabsorb iodide efficiently. 4. Very large mammals are protected against renal loss of iodide due to the relatively low GFR. 5. Thyroid weights in relation to body weight were highest in humans suggesting that humans and other mammals of a similar size are especially susceptible to iodine deficiency.     

Vocal mimicry of computer-generated sounds and vocal labeling of objects by a bottlenosed dolphin, Tursiops truncatus..

A female bottlenosed dolphin was trained to mimic computer-generated "model" sounds, using a whistle mode of vocalization. Prior to training, the whistle sounds of the S were limited to a few stereotyped forms. After training, high-fidelity imitations were obtained of model sounds having a variety of frequency characteristics. New models, could be mimicked immediately, often with good fidelity, including mimicry of amplitude variation that had not been explicitly reinforced during training. Subsets of familiar models were mimicked with high reliability in repeated tests. In additional training, control of the mimic response was transferred from the acoustic model to objects (e.g., a ball or hoop) shown to the S so that, in effect, the S gave unique vocal labels to those objects. In a test of accuracy and reliability of labeling, correct vocal labels were given on 91% of 167 trials comprised of 5 objects presented in random order. S's ability for vocal mimicry compared favorably with that of the more versatile mimic birds, and it contrasted sharply with the apparent lack of vocal mimicry ability in terrestrial mammals other than humans. The ability to label objects vocally was similar to abilities shown for some birds and similar, in principle, to abilities of great apes trained in visual languages to label objects through gestures or other visual symbols. (85 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absolute pitch: Frequency-range discriminations in pigeons (Columba livia)--comparisons with zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

Absolute pitch (AP) is the ability to classify individual pitches without an external referent. The authors compared results from pigeons (Columba livia, a nonsongbird species) with results (R. Weisman, M. Njegovan, C. Sturdy, L. Phillmore, J. Coyle, & D. Mewhort, 1998) from zebra finches (Taeniopygia guttata, a songbird species) and humans (Homo sapiens) in AP tests that required classification of contiguous tones into 3 or 8 frequency ranges on the basis of correlations between the tones in each frequency range and reward. Pigeons' 3-range discriminations were similar in accuracy to those of zebra finches and humans. In the more challenging 8-range task, pigeons, like zebra finches, discriminated shifts from reward to nonreward from range to range across all 8 ranges, whereas humans discriminated only the 1st and last ranges. Taken together with previous research, the present experiments suggest that birds may have more accurate AP than mammals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Raman difference spectroscopy of tertiary and quaternary structure changes in methaemoglobins

There have been several resonance Raman scattering investigations of the effect of inositol hexaphosphate (IHP) on methaemoglobins. In those studies the sensitivity for detecting frequency differences was limited to 1-2 cm-1, and consequently frequency differences were not detected although spectral intensity differences due to changes in spin equilibria were. Shelnutt et al. recently reported on the observation of frequency differences induced by changes in the quaternary structure of chemically modified deoxyhaemoglobins. An improved Raman difference spectroscopic technique with 0.1 cm-1 sensitivity allowed the detection of these differences. We report here the application of this technique to a series of methaemoglobins with and without the addition of IHP. In addition to the intensity changes resulting from changes in the spin equilibria, we have observed frequency differences. In all liganded methaemo-globins that we examined a decrease in frequency of the mode in the 1,370 cm-1 region was observed on addition of IHP. In those in which a quaternary structure change is known to occur the frequency difference is greater than 0.5 cm-1. In those in which no quaternary structure change occurs [metHbA(CN-) and methHbA(N-3)] the frequency difference is smaller (approximately 0.15 cm-1).     

Immunotoxic effects of organotin compounds in Tapes philippinarum

One of the most harmful groups of coastal pollutants is the organotin compounds (OTCs) which have severe effects on both aquatic organisms and mammals including humans. The immunotoxic effects of OTCs were studied in the cultivated clam Tapes philippinarum by determining the immunosuppressant role on in vitro yeast phagocytosis at low doses (0.01, 0.05, 0.1 microM). The phagocytic index was significantly reduced in an irreversible non-lethal manner depending on concentration and lipophilic affinity. The order of inhibition was TBT > or = DBT > MBT for butyltins and TPTC > TPTA > or = TPTH for triphenyltins.     

Auditory frequency discrimination in primates: Species differences (Cercopithecus, Macaca, Homo).

Auditory frequency difference limens (DLs) at 2 kHz were measured in Old World monkeys (Cercopithecus, Macaca) and humans using a go/no-go repeating standard procedure and positive reinforcement operant conditioning techniques. Quantitative and qualitative differences occurred between monkey and human sensitivity. Best DLs for monkeys were 20–60 Hz, and for humans they were 3–4 Hz. Monkey sensitivity decreased as sensation level increased from 30 to 70 dB, whereas human sensitivity increased. Sensitivity differences also occurred in the various monkey species. Cercopithecus monkeys were generally more sensitive to frequency decrements, whereas Japanese macaques were more sensitive to frequency increments, as were humans. Results are related to other comparative psychoacoustic data and primate vocal communication, including human speech. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The flavin-containing monooxygenase 2 gene (FMO2) of humans, but not of other primates, encodes a truncated, nonfunctional protein

Flavin-containing monooxygenases (FMOs) are NADPH-dependent flavoenzymes that catalyze the oxidation of heteroatom centers in numerous drugs and xenobiotics. FMO2, or "pulmonary" FMO, one of five forms of the enzyme identified in mammals, is expressed predominantly in lung and differs from other FMOs in that it can catalyze the N-oxidation of certain primary alkylamines. We describe here the isolation and characterization of cDNAs for human FMO2. Analysis of the sequence of the cDNAs and of a section of the corresponding gene revealed that the major FMO2 allele of humans encodes a polypeptide that, compared with the orthologous protein of other mammals, lacks 64 amino acid residues from its C terminus. Heterologous expression of the cDNA revealed that the truncated polypeptide was catalytically inactive. The nonsense mutation that gave rise to the truncated polypeptide, a C --> T transition in codon 472, is not present in the FMO2 gene of closely related primates, including gorilla and chimpanzee, and must therefore have arisen in the human lineage after the divergence of the Homo and Pan clades. Possible mechanisms for the fixation of the mutation in the human population and the potential significance of the loss of functional FMO2 in humans are discussed.     

Sensitivity to interaural time differences in the medial superior olive of a small mammal, the Mexican free-tailed bat

Neurons in the medial superior olive (MSO) are thought to encode interaural time differences (ITDs), the main binaural cues used for localizing low-frequency sounds in the horizontal plane. The underlying mechanism is supposed to rely on a coincidence of excitatory inputs from the two ears that are phase-locked to either the stimulus frequency or the stimulus envelope. Extracellular recordings from MSO neurons in several mammals conform with this theory. However, there are two aspects that remain puzzling. The first concerns the role of the MSO in small mammals that have relatively poor low-frequency hearing and whose heads generate only very small ITDs. The second puzzling aspect of the scenario concerns the role of the prominent binaural inhibitory inputs to MSO neurons. We examined these two unresolved issues by recording from MSO cells in the Mexican free-tailed bat. Using sinusoidally amplitude-modulated tones, we found that the ITD sensitivities of many MSO cells in the bat were remarkably similar to those reported for larger mammals. Our data also indicate an important role for inhibition in sharpening ITD sensitivity and increasing the dynamic range of ITD functions. A simple model of ITD coding based on the timing of multiple inputs is proposed. Additionally, our data suggest that ITD coding is a by-product of a neuronal circuit that processes the temporal structure of sounds. Because of the free-tailed bat's small head size, ITD coding is most likely not the major function of the MSO in this small mammal and probably other small mammals.     

Nucleotide sequence of an alternative glucoamylase-encoding gene (glaB) expressed in solid-state culture of Aspergillus oryzae

The potential health effects of environmental contaminants in traditional food has become a concern among northern communities because of the presence of environmental contaminants in the Arctic ecosystem. Exposure assessments are needed but they require comprehensive dietary information and contaminant data. Over the last 10 years, there has been considerable effort to monitor the level of contaminants in fish and wildlife collected from different regions in northern and Arctic Canada. The development of a database and its application for dietary contaminant exposure assessment are described. We conducted an extensive literature review on levels of environmental contaminants in northern and Arctic Canada. The ranges of levels of four contaminants of major concern (chlordane, mercury, polychlorinated biphenyls and toxaphene) in 81 species of marine mammals, terrestrial mammals, birds, fish and plants are summarized. These data represent 69% of the 117 species of fish, wildlife and plants mentioned in our dietary interviews conducted in the northern communities. A significant percentage of the foods had contaminant levels exceeding the guidelines used by Health Canada for market food consumed by the 'southern' populations. Mathematic modelling of the distributions of the data showed that contaminant levels in most food groups are log-normally distributed and have a typical coefficient of variation of about 100%. Examples are presented to demonstrate the use of the data for contaminant exposure assessment. Average contaminant exposure levels estimated using the database for two communities are comparable to those obtained previously using community specific data. With the current knowledge of environmental contaminant levels in the northern traditional food system, it may be feasible to conduct preliminary risk assessment of dietary exposure of environmental contaminants when some diet information for a community is available. Further sampling and analysis may be needed only for confirmation purposes.     

Primary Mycobacterium avium complex infections correlate with lowered cellular immune reactivity in Matschie's tree kangaroos (Dendrolagus matschiei)

The National Zoological Park has maintained a breeding colony of Matschie's tree kangaroos (Dendrolagus matschiei) since 1975 with a documented history and continued prevalence of Mycobacterium avium complex (MAC) infections. No evidence of immunosuppressive retrovirus infections or loss of heterozygosity that may have led to an immune dysfunction in these animals was found. Isolates of MAC organisms from affected tree kangaroos and from their environment had no common restriction fragment DNA types. Cellular immune reactivity in apparently healthy tree kangaroos was 3- to 6-fold lower than in humans and other marsupial and eutherian mammals, as determined by lymphocyte proliferative assays. Thus, while MAC infections are typically opportunistic in humans and other mammals, tree kangaroos commonly develop primary progressive disease with MAC from random sources. Comparative information derived from this study should benefit both the endangered tree kangaroo and humans with immunosuppressive disorders that lead to mycobacterial infections.     

In defense of Nephila clavipes: Postmate guarding by the male golden orb-weaving spider.

We assessed the frequency and intensity of postmate defensive behavior in N. clavipes and its effect on a male's reproductive success. We staged two types of agonistic encounters and analyzed census data on marked, unrestrained animals. First, males were introduced to the webs of mated pairs 3 days after the females' final molt. Mated males defended their position with a frequency and intensity comparable with that of males tested on juvenile females' orbs in past studies. Second, we found that males even defended orbs 24 hrs after the female had been removed. Third, census data indicate that rates of aggression were comparable on juvenile females' and mature adults' orbs and that the benefits of defense appear limited. Females changed web site soon after mating, thereby limiting male defense of the female. Postmate defense did not reduce the likelihood of a female mating with subsequent males. It appears that the male N. clavipes strategy is simple: Regardless of the female's status, seek the hub position and defend it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognition in an African gray parrot (Psittacus erithacus): Further evidence for comprehension of categories and labels.

This experiment was designed to examine further the comprehension skills of an African gray parrot (Psittacus erithacus). For each test trial the parrot was shown a different collection of 7 physical exemplars (each collection chosen from among 100 objects of various combinations of shapes, colors, and materials); was asked 1 of 4 possible vocal questions, each of which requested a different type of information (e.g., "What color is [designated object]?") about a single object in the collection; and was required to reply vocally to each question. A correct response indicated that the parrot understood all the elements of the question and used these elements to guide the search for the 1 object in the collection that provided the requested information. The bird responded with an accuracy of 81.3%, which suggests that his capacities are comparable to those of nonhuman primates and marine mammals that have been trained on similar tasks that involve comprehension of categories and labels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Absolute auditory thresholds in three Old World monkey species (Cercopithecus aethiops, C. neglectus, Macaca fuscata) and humans (Homo sapiens).

We investigated the absolute auditory sensitivities of three monkey species (Cercopithecus aethiops, C. neglectus, and Macaca fuscata) and humans (Homo sapiens). Results indicated that species-typical variation exists in these primates. Vervets, which have the smallest interaural distance of the species that we tested, exhibited the greatest high-frequency sensitivity. This result is consistent with Masterton, Heffner, and Ravizza's (1969) observations that head size and high-frequency acuity are inversely correlated in mammals. Vervets were also the most sensitive in the middle frequency range. Furthermore, we found that de Brazza's monkeys, though they produce a specialized, low-pitched boom call, did not show the enhanced low-frequency sensitivity that Brown and Waser (1984) showed for blue monkeys (C. mitis), a species with a similar sound. This discrepancy may be related to differences in the acoustics of the respective habitats of these animals or in the way their boom calls are used. The acuity of Japanese monkeys was found to closely resemble that of rhesus macaques (M. mulatta) that were tested in previous studies. Finally, humans tested in the same apparatus exhibited normative sensitivities. These subjects responded more readily to low frequencies than did the monkeys but rapidly became less sensitive in the high ranges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frequency–range discriminations: Special and general abilities in zebra finches (Taeniopygia guttata) and humans (Homo sapiens).

The acoustic frequency ranges in birdsongs and human speech can provide important pitch cues for recognition. Zebra finches and humans were trained to sort contiguous frequencies into 3 or 8 ranges, based on associations between the ranges and reward. The 3-range task was conducted separately in 3 spectral regions. Zebra finches discriminated 3 ranges in the medium and high spectral regions faster than in the low region and discriminated 8 ranges with precision. Humans discriminated 3 ranges in all 3 spectral regions to the same modest standard and acquired only a crude discrimination of the lowest and highest of 8 ranges. The results indicate that songbirds have a special sensitivity to the pitches in conspecific songs and, relative to humans, have a remarkable general ability to sort pitches into ranges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cloning and localization of two multigene receptor families in goldfish olfactory epithelium

Goldfish reproduction is coordinated by pheromones that are released by ovulating females and detected by males. Two highly potent pheromones, a dihydroxyprogesterone and a prostaglandin, previously have been identified, and their effects on goldfish behavior have been studied in depth. We have cloned goldfish olfactory epithelium cDNAs belonging to two multigene G-protein coupled receptor families as a step toward elucidating the molecular basis of pheromone recognition. One gene family (GFA) consists of homologs of putative odorant receptors (approximately 320 residues) found in the olfactory epithelium of other fish and mammals. The other family (GFB) consists of homologs of putative pheromone receptors found in the vomeronasal organ (VNO) of mammals and also in the nose of pufferfish. GFB receptors (approximately 840 residues) are akin to the V2R family of VNO receptors, which possess a large extracellular N-terminal domain and are homologs of calcium-sensing and metabotropic glutamate receptors. In situ hybridization showed that the two families of goldfish receptors are differentially expressed in the olfactory epithelium. GFB mRNA is abundant in rather compact cells whose nuclei are near the apical surface. In contrast, GFA mRNA is found in elongated cells whose nuclei are positioned deeper in the epithelium. Our findings support the hypothesis that the separate olfactory organ and VNO of terrestrial vertebrates arose in evolution by the segregation of distinct classes of neurons that were differentially positioned in the olfactory epithelium of a precursor aquatic vertebrate.     

Optimizing sound features for cortical neurons

The brain's cerebral cortex decomposes visual images into information about oriented edges, direction and velocity information, and color. How does the cortex decompose perceived sounds? A reverse correlation technique demonstrates that neurons in the primary auditory cortex of the awake primate have complex patterns of sound-feature selectivity that indicate sensitivity to stimulus edges in frequency or in time, stimulus transitions in frequency or intensity, and feature conjunctions. This allows the creation of classes of stimuli matched to the processing characteristics of auditory cortical neurons. Stimuli designed for a particular neuron's preferred feature pattern can drive that neuron with higher sustained firing rates than have typically been recorded with simple stimuli. These data suggest that the cortex decomposes an auditory scene into component parts using a feature-processing system reminiscent of that used for the cortical decomposition of visual images.