The Spatial Origins of Cochlear Amplification Assessed by Stimulus-Frequency Otoacoustic Emissions

Cochlear amplification of basilar membrane traveling waves is thought to occur between a tone’s characteristic frequency (CF) place and within one octave basal of the CF. Evidence for this view comes only from the cochlear base. Stimulus-frequency otoacoustic emissions (SFOAEs) provide a noninvasive alternative to direct measurements of cochlear motion that can be measured across a wide range of CF regions. Coherent reflection theory indicates that SFOAEs arise mostly from the peak region of the traveling wave, but several studies using far-basal suppressor tones claimed that SFOAE components originate many octaves basal of CF. We measured SFOAEs while perfusing guinea pig cochleas from apex to base with salicylate or KCl solutions that reduced outer-hair-cell function and SFOAE amplification. Solution effects on inner hair cells reduced auditory nerve compound action potentials (CAPs) and provided reference times for when solutions reached the SFOAE-frequency CF region. As solution flowed from apex to base, SFOAE reductions generally occurred later than CAP reductions and showed that the effects of cochlear amplification usually peaked ∼1/2 octave basal of the CF region. For tones ≥2 kHz, cochlear amplification typically extended ∼1.5 octaves basal of CF, and the data are consistent with coherent reflection theory. SFOAE amplification did not extend to the basal end of the cochlea, even though reticular lamina motion is amplified in this region, which indicates that reticular lamina motion is not directly coupled to basilar membrane traveling waves. Previous reports of SFOAE-frequency residuals produced by suppressor frequencies far above the SFOAE frequency are most likely due to additional sources created by the suppressor. For some tones <2 kHz, SFOAE amplification extended two octaves apical of CF, which highlights that different vibratory motions produce SFOAEs and CAPs, and that the amplification region depends on the cochlear mode of motion considered. The concept that there is a single “cochlear amplification region” needs to be revised.     

Ultrastructure of the domestic tom cat (Felis domestica ) and tiger (Panthera tigris altaica ) spermatozoa

The ultrastructure of spermatozoa from the domestic tom cat and the Siberian tiger was studied. Semen was collected from anesthetized tom cats and Siberian tigers by electroejaculation. Spermatozoa were fixed and processed for examination by transmission electron microscopy. The principle differences between the spermatozoa from the two species were the head shape, mitochondrial organization in the neck area and structure of the fibrous sheath. Tom cat spermatozoa had an elongated oval-shaped head, while tiger spermatozoa had a more rounded head shape. Circularly oriented mitochondria in the neck area, near the proximal centriole, were frequently observed in tiger cells but rarely observed in tom cat cells. The semicircular ribs of tom cat spermatozoa were larger than the ribs of tiger spermatozoa. Also, the dense fibers (Numbers 3 and 8) of the corresponding microtubule doublets were fused or connected to the longitudinal columns in tiger spermatozoa but showed only occasional attachment in tom cat spermatozoa. These differences could influence results when the tom cat is used as a model for studying tiger semen.     

Cochlear Delay and Medial Olivocochlear Functioning in Children with Suspected Auditory Processing Disorder

Behavioral manifestations of processing deficits associated with auditory processing disorder (APD) have been well documented. However, little is known about their anatomical underpinnings, especially cochlear processing. Cochlear delays, a proxy for cochlear tuning, measured using stimulus frequency otoacoustic emission (SFOAE) group delay, and the influence of the medial olivocochlear (MOC) system activation at the auditory periphery was studied in 23 children suspected with APD (sAPD) and 22 typically developing (TD) children. Results suggest that children suspected with APD have longer SFOAE group delays (possibly due to sharper cochlear tuning) and reduced MOC function compared to TD children. Other differences between the groups include correlation between MOC function and SFOAE delay in quiet in the TD group, and lack thereof in the sAPD group. MOC-mediated changes in SFOAE delay were in opposite directions between groups: increase in delay in TD vs. reduction in delay in the sAPD group. Longer SFOAE group delays in the sAPD group may lead to longer cochlear filter ringing, and potential increase in forward masking. These results indicate differences in cochlear and MOC function between sAPD and TD groups. Further studies are warranted to explore the possibility of cochlea as a potential site for processing deficits in APD.     

Isolation of preantral follicles from nondomestic cats—viability and ultrastructural investigations

Large scale isolation of small preantral follicles (40–90 μm) from nondomestic cats (lion, puma, cheetah, jaguar, and three kinds of tigers) is described and compared with domestic cats. The viability of preantral follicles was estimated by trypan blue staining of granulosa cells and/or by 5-bromo-2′-deoxy-uridine (BrdU) incorporation into oocytes and granulosa cells during short term culture. Native and isolated preantral follicles were compared ultrastructurally. In nondomestic cats the mechanical dissection of ovaries provided 0–12 500 follicles per ovary with a viability of 20–50%, estimated by trypan blue staining. Even the follicles recovered from domestic cats, whose ovaries are considerable smaller than ovaries from all other felids, are characterised by only 28.7% viable follicles. The follicles from one Siberian tiger and three Indian lions were cultivated and their in vitro viability assessed by BrdU labelling. Lion follicles were comparable to domestic cat follicles with respect to BrdU incorporation. Tiger follicles were characterised by a decreased staining of granulosa cells.The ultrastructure of feline oocytes appears similar to that of most mammalian species and was only slightly affected during the isolation procedure. A central vesicular body was only observed in tiger oocytes.     

Tectorial Membrane Morphological Variation: Effects upon Stimulus Frequency Otoacoustic Emissions

The tectorial membrane (TM) is widely believed to play an important role in determining the ear's ability to detect and resolve incoming acoustic information. While it is still unclear precisely what that role is, the TM has been hypothesized to help overcome viscous forces and thereby sharpen mechanical tuning of the sensory cells. Lizards present a unique opportunity to further study the role of the TM given the diverse inner-ear morphological differences across species. Furthermore, stimulus-frequency otoacoustic emissions (SFOAEs), sounds emitted by the ear in response to a tone, noninvasively probe the frequency selectivity of the ear. We report estimates of auditory tuning derived from SFOAEs for 12 different species of lizards with widely varying TM morphology. Despite gross anatomical differences across the species examined herein, low-level SFOAEs were readily measurable in all ears tested, even in non-TM species whose basilar papilla contained as few as 50-60 hair cells. Our measurements generally support theoretical predictions: longer delays/sharper tuning features are found in species with a TM relative to those without. However, SFOAEs from at least one non-TM species (Anolis) with long delays suggest there are likely additional micromechanical factors at play that can directly affect tuning. Additionally, in the one species examined with a continuous TM (Aspidoscelis) where cell-to-cell coupling is presumably relatively stronger, delays were intermediate. This observation appears consistent with recent reports that suggest the TM may play a more complex macromechanical role in the mammalian cochlea via longitudinal energy distribution (and thereby affect tuning). Although significant differences exist between reptilian and mammalian auditory biophysics, understanding lizard OAE generation mechanisms yields significant insight into fundamental principles at work in all vertebrate ears.     

虎物种特异性鉴定的 PCR 方法研究

为了建立可对虎DNA 进行特异性检测的PCR 方法, 应用在野外调查中获得的虎疑似样品和保护执法工作中难以检查辨认的虎产品进行物种鉴定, 从Genbank 数据库下载5 个虎亚种及其它6 种猫科动物和6 种鹿科动物的mtDNA 细胞色素b 基因序列, 并用Wdnasis (V2.5) 软件对上述不同动物的该基因碱基序列进行比较。在此基础上, 综合考虑了设计引物的基本原则, 选择了虎与其它动物碱基序列上差异位点较多的两个片段, 设计出PCR 引物(引物1、2) 。用该对引物分别对从东北虎、华南虎及8 种猫科动物和6 种非猫科动物的肌肉、脏器组织、皮或毛发中提取的DNA 进行PCR (聚合酶链反应) 扩增。结果表明, 所设计的引物对虎DNA 具有特异性,从而达到了对该物种进行特异性检测鉴定的目的。     

Evaluation of nutrient digestibility and fecal characteristics of exotic felids fed horse‐ or beef‐based diets: use of the domestic cat as a model for exotic felids

The objective of this study was to determine the effects of feeding commercially available beef‐ and horse‐based diets on nutrient digestibility and fecal characteristics of large captive exotic felids and domestic cats. Four species of large exotic felids including cheetahs, Malayan tigers, jaguars, and Amur tigers, and domestic cats were utilized in a crossover design. Raw meat diets included a beef‐based diet (57% protein; 28% fat) and a horse‐based diet (51% protein; 30% fat). All cats were acclimated to the diet for 16 days followed by a 4 day collection period, where total feces, including one fresh sample, were collected. All feces were scored on collection. Intake did not differ due to diet, but fecal output was greater when cats consumed the horse‐based diet. Total tract apparent dry matter (DM) digestibility was higher (P<0.05) and organic matter (OM) and crude protein (CP) digestibilities were lower (P<0.05) when cats were fed the beef‐based diet compared with the horse‐based diet. CP digestibility was similar in domestic cats and cheetahs, and greater (P<0.05) than Amur tigers. Fecal scores were lower and fecal DM was greater (P<0.05) when cats consumed the horse‐based diet compared with the beef‐based diet. Domestic cats had lower (P<0.05) fecal ammonia concentrations compared with all other species. Fecal ammonia concentrations were lowest (P<0.05) when cats were fed the horse‐based diet. Fecal total short‐chain fatty acid (SCFA), branched‐chain fatty acid (BCFA), and butyrate concentrations were higher (P<0.05) when cats consumed the beef‐based diet. Our results suggest that the domestic cat serves as an appropriate model for large exotic felid species, but differences among the species exist. Decreased nutrient digestibility by tigers and jaguars should be considered when developing feeding recommendations for these species based on domestic cat data. Zoo Biol 29:432–448, 2010. © 2009 Wiley‐Liss, Inc.     

Oldest known pantherine skull and evolution of the tiger

The tiger is one of the most iconic extant animals, and its origin and evolution have been intensely debated. Fossils attributable to extant pantherine species-lineages are less than 2 MYA and the earliest tiger fossils are from the Calabrian, Lower Pleistocene. Molecular studies predict a much younger age for the divergence of modern tiger subspecies at <100 KYA, although their cranial morphology is readily distinguishable, indicating that early Pleistocene tigers would likely have differed markedly anatomically from extant tigers. Such inferences are hampered by the fact that well-known fossil tiger material is middle to late Pleistocene in age. Here we describe a new species of pantherine cat from Longdan, Gansu Province, China, Panthera zdanskyi sp. nov. With an estimated age of 2.55-2.16 MYA it represents the oldest complete skull of a pantherine cat hitherto found. Although smaller, it appears morphologically to be surprisingly similar to modern tigers considering its age. Morphological, morphometric, and cladistic analyses are congruent in confirming its very close affinity to the tiger, and it may be regarded as the most primitive species of the tiger lineage, demonstrating the first unequivocal presence of a modern pantherine species-lineage in the basal stage of the Pleistocene (Gelasian; traditionally considered to be Late Pliocene). This find supports a north-central Chinese origin of the tiger lineage, and demonstrates that various parts of the cranium, mandible, and dentition evolved at different rates. An increase in size and a reduction in the relative size of parts of the dentition appear to have been prominent features of tiger evolution, whereas the distinctive cranial morphology of modern tigers was established very early in their evolutionary history. The evolutionary trend of increasing size in the tiger lineage is likely coupled to the evolution of its primary prey species.     

What determines attitude of local people towards tiger and leopard in Nepal?

Understanding attitude of local people towards big cats is vital for conservation interventions to succeed. Taking tigers and leopards as focal species, we investigated local peoples' attitude towards four subjects—tiger, tiger conservation, leopard, and leopard conservation—considering demographic and socio-economic factors as well as past experience with such predators in Nepal's first national park and a world heritage site, Chitwan National Park. The data were collected from 414 local people using structured questionnaires and their attitude towards the four subjects determined. We performed ordinal logistic regression analysis to identify the best fitted model and significant variables affecting attitudes. While majority of the people (51%) strongly liked tigers, fewer people (38%) had similar view while it came to leopard. However, a greater proportion of people strongly agreed that the conservation of tigers (61%) and leopards (53%) is important. About 12% people had negative attitude towards both big cats. We found women and low income respondents to likely have negative attitudes and higher caste Hindus to have positive attitudes towards both big cats and their conservation. Better educated persons and the owners to larger herds of livestock only agreed on conservation of tiger but not leopard. Past experience with the predator negatively affected attitude towards tiger but not leopard. We suggest the identified cohort of people with negative attitudes be more targeted in conservation initiatives. The reasons behind the similarities and differences in peoples’ attitudes are discussed and designation of species-specific programmes for both cats is recommended.     

Embryo technology in conservation efforts for endangered felids

Most of the 36 species of wild cats are classified as threatened, vulnerable or endangered due to poaching and habitat loss. The important role of assisted reproduction techniques (ART) as part of a multifaceted captive breeding program for selected wild cat species is gradually gaining acceptance. This recognition is a result of the progress made during the last decade in which the feasibility of oocyte recovery from gonadotropin-treated females, in vitro fertilization, embryo cryopreservation and embryo transfer (ET) was demonstrated in the domestic cat (Felis catus). Additionally, embryos have been produced in vitro from oocytes matured in vitro after recovery from ex situ ovaries of both domestic and non-domestic cat species and domestic kittens have been born following transfer of these embryos. In vitro fertilization has been successful in at least one-third of wild cat species and kittens were born after transfer of Indian desert cat (Felis sylvestris ornata) embryos into a domestic cat and con-specific transfer of tiger (Panthera tigris) embryos. The domestic cat is not only a valuable model for development of in vitro techniques but may serve as a recipient of embryos from several species of small wild cats.     

Ability of thawed tiger (Panthera tigris) spermatozoa to fertilize conspecific eggs and bind and penetrate domestic cat eggs in vitro.

Electroejaculates from tigers were collected and half was used fresh to inseminate tiger eggs in vitro and domestic cat eggs stored in a hypertonic salt solution. The remainder was pelleted, frozen in a solution of 20% egg yolk, 11% lactose and 4% glycerol, thawed and cultured with tiger and domestic cat eggs. The motility index ((sperm % motility)+(status rating x 20))/2 for thawed spermatozoa was about 86% of that in fresh aliquots. Of the 49 tiger oocytes inseminated in vitro with fresh spermatozoa, 34 (69.4%) cleaved, compared with 33 of 47 oocytes (70.2%) cultured with thawed spermatozoa (P > 0.05). Embryos generated by either sperm treatment could develop in vitro to the 16-cell or morula stage. Fresh and thawed tiger spermatozoa were equally capable (P > 0.05) of binding and penetrating the outer and inner zona pellucida of domestic cat eggs. These results demonstrate the ability of frozen-thawed tiger spermatozoa to (i) penetrate homologous and heterologous eggs and (ii) result in conspecific, advanced development of preimplantation embryos in vitro.     

Fourteen new di- and tetranucleotide microsatellite loci for the critically endangered Indian tiger (Panthera tigris tigris)

We describe 11 dinucleotide and three tetranucleotide microsatellite loci for the critically endangered Indian tiger, Panthera tigris tigris. All of them were polymorphic with four to nine alleles per locus and an observed heterozygosity between 0.13 and 1.0. All primers also amplify microsatellite loci in leopard, Panthera pardus, and 12 primer pairs yielded reproducible results in domestic cat, Felis catus. These new microsatellites specifically developed for Indian tiger - in combination with those already available - comprise a reasonable number of loci to genetically analyse wild and captive populations of this illustrative species and might allow for recognition of individual tigers.     

Relating middle-ear acoustic performance to body size in the cat family: measurements and models

Is the acoustic performance of the mammalian middle ear dependent on body size? We focus on the cat family, because of its qualitatively uniform (and distinctive) middle-ear structure, large size range, and the extensive data available from domestic cats which provide a framework for relating middle-ear acoustics to structure. We report measurements of acoustic admittance in 17 live adult ears of 11 exotic species, ranging in size from sand cat (3?kg) to tiger (180?kg). For low frequencies, the middle-ear response is compliant for all species and generally increases with size. The compliance of the middle-ear air space increases with size, but the compliance of the tympanic membrane and ossicular chain is not correlated with size. Structure-based rules are developed to represent some features of middle-ear performance: (1) low-frequency sensitivity increases with size; and (2) the frequency of a prominent notch in admittance decreases with size. Although some species deviate from the rules, the data generally support the idea that in larger felids the middle-ear response is shifted to lower frequencies. Thus, in the cat family, body size partly describes variations in auditory features. More speculatively, ethological pressures which might influence hearing performance are discussed.     

虎源猫泛白细胞减少症病毒灭活疫苗的制备及初步应用

摘要：【目的】研制出虎源猫泛白细胞减少症病毒灭活疫苗并对其应用效果进行评价。【方法】以FPV-HLJ为种毒,按1×10-2接毒量,采用同步接毒的方法接于猫肾传代细胞系F81株,于37 ℃静置培养,待细胞病变（CPE）达到75 %以上时,进行收毒。病毒悬液经甲醛灭活24 h,加入佐剂氢氧化铝胶,制备成FPV-HLJ细胞培养灭活疫苗。【结果】皮下接种2月龄非免疫家猫,结果显示,实验组免疫猫FPV HI抗体水平随免疫次数的增加而呈上升趋势,三免后FPV HI抗体效价为1:1024～1：2048,且免疫猫能抵抗FPV强毒攻击,具有100 %的存活率。随后将该苗接种2月龄左右幼虎,三免后抗体效价多数能达到1：1024。【结论】表明此灭活苗可产生较为理想的免疫效果。     

Do tigers displace leopards? If so, why?

We investigated predictions concerning the competitive relationships between tigers Panthera tigris and leopards Panthera pardus in Bardia National Park, Nepal, based on spatial distributions of scats and territorial markings (sign), analyses of scat content and census of wild ungulate prey. Medium-sized ungulates, in particular chital Axis axis, was the main food of both predators, but leopards consumed significantly larger proportions of domestic animals, small mammals, and birds than tigers. Tiger sign were never found outside the park, while leopard sign occurred both inside and outside, and were significantly closer to the park border than tiger sign. Significantly higher prey densities at locations of tiger sign than that of leopards were mainly due to a preference of the latter species for the park border areas. Our results imply that interference competition––and not competition for food––was a limiting factor for the leopard population, whose distribution was restricted to the margins of the tiger territories. We suggest that the composition of the prey base is a key factor in understanding the different results and interpretations reported in studies on tiger/leopard coexistence. There are two potential mechanisms that link interference competition and prey: (1) low abundance of large ungulate prey decreases foraging efficiency of tigers, leading to increased energetic stress and aggression towards leopards; and (2) increased diet overlap due to scarcity of large prey leads to increased encounter rates and increased levels of interference competition.     

Oscillating neurons in the cochlear nucleus: I. Experimental basis of a simulation paradigm

Anatomical and physiological auditory data and pitch measurements are presented including some additional analysis. The data provide the basis for a new computer model of sustained chopper neurons in the ventral cochlear nucleus. New and old evidence indicating a preference for multiples of 0.4 ms in oscillations of chopper neurons in the cochlear nucleus of different species such as man, cats, and Guinea fowls, is summarized. Our hypothesis is that the time constant of 0.4 ms is due to the minimum synaptic delay of chopper neuron connections. Anatomical findings show that chopper neurons are indeed connected and can excite each other; a model of a circular network of neurons that are connected via synapses with a delay of 0.4 ms is thus plausible. Results concerning frequency tuning and dynamical properties of periodicity encoding of chopper neurons are reviewed. It is concluded that chopper neurons receive input both from auditory nerve fibres and onset neurons.     

Recent Evolutionary History of Tigers Highlights Contrasting Roles of Genetic Drift and Selection

Species conservation can be improved by knowledge of evolutionary and genetic history. Tigers are among the most charismatic of endangered species and garner significant conservation attention. However, their evolutionary history and genomic variation remain poorly known, especially for Indian tigers. With 70% of the world’s wild tigers living in India, such knowledge is critical. We re-sequenced 65 individual tiger genomes representing most extant subspecies with a specific focus on tigers from India. As suggested by earlier studies, we found strong genetic differentiation between the putative tiger subspecies. Despite high total genomic diversity in India, individual tigers host longer runs of homozygosity, potentially suggesting recent inbreeding or founding events, possibly due to small and fragmented protected areas. We suggest the impacts of ongoing connectivity loss on inbreeding and persistence of Indian tigers be closely monitored. Surprisingly, demographic models suggest recent divergence (within the last 20,000 years) between subspecies and strong population bottlenecks. Amur tiger genomes revealed the strongest signals of selection related to metabolic adaptation to cold, whereas Sumatran tigers show evidence of weak selection for genes involved in body size regulation. We recommend detailed investigation of local adaptation in Amur and Sumatran tigers prior to initiating genetic rescue.     

Renal papillary necrosis in the tiger

Two examples of renal papillary necrosis in the tiger are described. The necrosis was characterised by large zones of liquefaction with minimal inflammation and was associated with pronouced scarring in the cortex. Both animals had been vomiting terminally and were severely dehydrated. It is suggested that papillary necrosis was precipitated by the reduced renal perfusion associated with dehydration in kidneys in which the medullary blood supply was already compromised by chronic cortical scarring. Comparisons are made between the lesions described in these tigers and those reported in the domestic cat, man and other domestic animals.     

Mechanical adaptations for echolocation in the cochlea of the bat Hipposideros lankadiva

The cochlear mechanics of bats with long constant-frequency components in their echolocation calls are sharply tuned to the dominant second harmonic constant frequency. Hipposiderid bats employ a shorter constant-frequency call component whose frequency is less stable than in long-constant-frequency bats. To investigate to what degree cochlear mechanics in hipposiderid bats are already specialized for the processing of constant frequencies, we recorded distortion-product otoacoustic emissions in Hipposideros lankadiva. Iso-distortion threshold curves for the 2f1-f2 distortion-product otoacoustic emission reveal a threshold maximum close to the second harmonic constant frequency, between 65.0 and 70.0 kHz, and a second insensitivity close to the first harmonic constant frequency. The group delay of the 2f1-f2 distortion is prolonged for both frequency ranges, indicating that a specialized cochlear resonance may act to absorb the constant-frequency call components. Compared to long-constant-frequency bats, the threshold maximum at the second harmonic constant frequency is less pronounced and the optimum cochlear frequency separation is larger. Distortion-product otoacoustic emission suppression tuning curves and neuronal tuning curves recorded from neurons in the cochlear nucleus display an increase of tuning sharpness close to the second harmonic constant-frequency range which is smaller than that reported for long-constant-frequency bats. Our data suggest that the cochlea of hipposiderid bats represents an intermediate state between that of non-specialized bats and long-constant-frequency bats.