The use of different eye regions in the mantis shrimp Hemisquilla californiensis Stephenson, 1967 (Crustacea: Stomatopoda) for detecting objects

A behavioral assay was used to assess the ability of the stomatopod Hemisquilla californiensis to perceive and respond to a moving target under different wavelengths and intensities of light illumination. Subjects responded to targets rotating horizontally across their visual field by a brief startle response of their eyes or antennules but did not track the targets. Under white light responses were elicited down to a light intensity of 0.9 μW cm^− 2. Responses were seen in blue light at intensities as low as 0.5 μW cm^− 2, and in green light down to 1.0 μW cm^− 2. The animals were less sensitive to red light, with no responses seen at intensities below 3.0 μW cm^− 2. Subjects did not respond to the targets at all under infrared light. This response pattern mirrors the computed sensitivity spectrum of ommatidia in the species' peripheral hemispheres but not that in most of the central bands. We conclude that this species uses the monochromatic vision in the peripheral hemispheres of its eyes to recognize objects and that the sharply tuned color receptors of the central band serve to add supplemental information if light conditions allow.     

A unique sound production mechanism in the pipid anuran Xenopus borealis

The totally aquatic pipid frog Xenopus borealis produces long trains of click-like sound at high sound pressure levels (> 105 dB SPL) underwater at night. While X. borealis retains an essentially terrestrial respiratory tract, the larynx is highly modified in two ways. First, the cricoid cartilage is greatly expanded posteriorly to form a large 'box'. Portions of this cricoid box are composed of an unusual elastic cartilage. Second, portions of the arytenoid cartilages are elaborated into calcified rods with disc-like enlargements at their posterior ends. These discs are the only freely moveable components within the larynx–there are no vocal cords. Artificial stimulation of a pair of muscles controlling the discs and discrete lesions that impair their movement demonstrate that motion of the discs is both necessary and sufficient for click production. Unlike all other anurans, X borealis does not use a moving air column in sound production. A possible mechanism of click production involves two steps: (1) at first, the discs are held tighdy apposed in the midline by fluid adhesive forces, and contraction of bipennate muscles is isometric; (2) when the muscle tension exceeds the adhesive force, the discs separate with very high acceleration leaving a vacuum between them. Air rushing into the space at high speed (an implosion) produces the click. The cricoid box shapes the frequency spectrum of the clicks, and opening the box broadens the power spectrum. The power spectrum of clicks produced by males after breathing helium is unchanged.     

Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters

Male katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (f_c) and pulse duration (p_d), were studied in 58 tropical species that use pure‐tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes in f_c and p_d. Anatomical changes of the sound generator that might have been selected via f_c and p_d are mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file‐teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae.     

Sound production in two species of damselfishes (Pomacentridae): Plectroglyphidodon lacrymatus and Dascyllus aruanus

Agonistic sounds of two pomacentrid species, Plectroglyphidodon lacrymatus and Dascyllus aruanus , were recorded in captivity. Plectroglyphidodon lacrymatus produced trains of 2–5 pops, each composed of 18–25 cycles, with an average duration of 56 ms; most energy ranged from c. 100 to 1000 Hz. Dascyllus aruanus produced pops and chirps. Pops were generally composed of a single pulse, with 2–14 peaks and an average duration of 6·7 ms. Pops contained energy >4 kHz, and peak frequency ranged from 680 to 1300 Hz. Chirps consisted of trains of 12–42 short pulses of three to six cycles, with durations varying from 0·6 to 1·27 ms; peak frequency varied from 3400 to 4100 Hz. Sound production in P. lacrymatus suggested that pomacentrids are derived from an ancestral taxon capable of sound production and that this capacity is a synapomorphy for the family. Although in the Pomacentridae, pops are typically composed of a single pulse, which is longer and higher pitched than chirps composed of a series of shorter pulses, D. aruanus chirps were higher pitched than its pops. Thus, acoustic variation in the genus Dascyllus is probably not more restricted than in the Pomacentridae.     

“Intentional” control of sound production found in leaf-clipping display of Mahale chimpanzees

This study reports three observed episodes involving leaf-clipping behavior of wild chimpanzees. In the first episode, an estrous female moved toward the source of a leaf-clipping sound. In the second, an estrous female escaped from a possessive male by intentionally controlling her production of sound. The third episode involved a male producing a leaf-clipping sound and then concealing the act when a dominant male approached. These episodes might suggest that chimpanzees can control the production of the sound intentionally, and understand that other chimpanzees also comprehend the causal relationship between the production of sounds and the occurrence of subsequent events.     

Acoustic signalling in female fish: factors influencing sound characteristics in croaking gouramis

The characteristics of sounds produced by fishes are influenced by several factors such as size. The current study analyses factors affecting structural properties of acoustic signals produced by female croaking gouramis Trichopsis vittata during agonistic interactions. Female sounds (although seldom analysed separately from male sounds) can equally be used to investigate factors affecting the sound characteristics in fish. Sound structure, dominant frequency and sound pressure levels (SPL) were determined and correlated to body size and the order in which sounds were emitted. Croaking sounds consisted of series of single-pulsed or double-pulsed bursts, each burst produced by one pectoral fin. Main energies were concentrated between 1.3 and 1.5 kHz. The dominant frequency decreased with size, as did the percentage of single-pulsed bursts within croaking sounds. The SPL and the number of bursts within a sound were independent of size but decreased significantly with the order of their production. Thus, acoustic signals produced at the beginning of agonistic interactions were louder and consisted of more bursts than subsequent ones. Our data indicate that body size affects the dominant frequency and structure of sounds. The increase in the percentage of double-pulsed bursts with size may be due to stronger pectoral muscles in larger fish. In contrast, ongoing fights apparently result in muscle fatigue and subsequently in a decline in the number of bursts and SPL. The factor ‘order of sound production’ points to an intra-individual variability of sounds and should be considered in future studies.     

Ultrasound production by genital stridulation in Syntonarcha iriastis (Lepidoptera: Pyralidae): long-distance signalling by male moths?

Males of the pyralid moth, Syntonarcha iriastis Meyrick, perch on vegetation at the tops of trees and bushes and produce ultrasound while their wings are spread and while sclerites at the end of the abdomen are spread to expose the genitalia. Exposing the genitalia appears to engage the sound-producing mechanism; the male genitalia and eighth abdominal sternite of this species are greatly modified and include a file and scraper and possible resonating areas. Sounds produced are consistent between individuals and comprise pulses which are narrow in frequency range, the first pulse being at about 42 kHz and two following pulses at about 57 kHz. The signal is detectable with an ultrasound 'bat' detector from 20 m. Two tettigoniid species (Orthoptera) at the same site produced ultrasonic calls of similar frequencies at the same times as the moth; differences in time-amplitude patterns could be used by orienting moths to recognize conspecifics. Signalling by male S. iriastis is compared with that of other pyralid species in which females are attracted to signalling males. The behaviour of S. iriastis males differs from that of other pyralids in that they do not signal in groups or from a resource attractive to females, and do not possess glands known to produce a 'calling' pheromone. It is suggested, because of these differences, that sound production in this species does not function at close range, as argued for the wax moth Achroia grisella (Fabricius), but instead as a long-distance calling signal.     

Morphological determinants of signal carrier frequency in katydids (Orthoptera): a comparative analysis using biophysical evidence of wing vibration

Male katydids produce mating calls by stridulation using specialized structures on the forewings. The right wing (RW) bears a scraper connected to a drum‐like cell known as the mirror and a left wing (LW) that overlaps the RW and bears a serrated vein on the ventral side, the stridulatory file. Sound is generated with the scraper sweeping across the file, producing vibrations that are amplified by the mirror. Using this sound generator, katydids exploit a range of song carrier frequencies (CF) unsurpassed by any other insect group, with species singing as low as 600 Hz and others as high as 150 kHz. Sound generator size has been shown to scale negatively with CF, but such observations derive from studies based on few species, without phylogenetic control, and/or using only the RW mirror length. We carried out a phylogenetic comparative analysis involving 94 species of katydids to study the relationship between LW and RW components of the sound generator and the CF of the male's mating call, while taking into account body size and phylogenetic relationships. The results showed that CF negatively scaled with all morphological measures, but was most strongly related to components of the sound generation system (file, LW and RW mirrors). Interestingly, the LW mirror (reduced and nonfunctional) predicted CF more accurately than the RW mirror, and body size is not a reliable CF predictor. Mathematical models were verified on known species for predicting CF in species for which sound is unknown (e.g. fossils or museum specimens).     

Sound production evoked by electrical stimulation of the forebrain in the oyster toadfish

In mammals, birds and amphibians the neural pathways controlling sound production descend from higher centers in the forebrain, whereas in fishes only brainstem and spinal centers have been explicitly implicated in sound production. We now report that electrical stimulation of the forebrain of the oyster toadfish (Opsanus tau) readily evokes both the agonistic grunt and the courtship boatwhistle. Boatwhistles are more realistic than ones previously evoked from lower centers. Positive stimulation sites are localized in the preoptic area (nucleus preopticus parvocellularis anterior) and the supracommissural nucleus of the ventral telencephalon, a likely homologue of the amygdala. Both sites contain gonadal steroid-concentrating neurons and play a central role in fish courtship behavior. Evoked sounds form a continuum from knock grunts, burst grunts, transition boatwhistles to complete boatwhistles; sound pressure level (SPL), fundamental frequency and duration increase consistently within the continuum. For all sound types, SPLs exhibit the smallest variation (coefficients of variation of 2.7 to 5.7%), fundamental frequency is intermediate (5 to 13%) and durations vary most widely (18 to 60%). Boatwhistles, with the smallest variation and greatest amplitude, are likely generated by a maximal output of the CNS and sonic muscles. Grunt SPLs however, vary over a range of 26 dB for all fish and by as much as 18 dB in an individual, suggesting recruitment of variable numbers of motor units despite electrical coupling within the sonic motor nucleus.Abbreviations AC anterior commissure - CNS central nervous system - DHT dihydrotestosterone - Dm medial nucleus of dorsal telenecphalon - DTAM dorsal tegmental area of medulla - E estrogen - HRP horseradish peroxidase - PM nucleus praeopticus magnocellularis - POA preoptic area - PPa nucleus praeopticus parvocellularis anterior - SMA sonic motor area - SMN sonic motor nucleus - SPL sound pressure level - T testosterone - VS supracommissural nucleus of ventral telencephalon - Vv ventral nucleus of ventral telencephalon     

Effect of calcitonin gene-related peptide on nitric oxide production in osteoblasts: an experimental study

The aim of this study was to investigate the in vitro effects and regulatory mechanism of CGRP (calcitonin gene-related peptide) on NO (nitric oxide) production in osteoblasts. MOB (primary human mandibular osteoblasts) and osteoblast-like cells (MG-63) were either cultured with CGRP or co-incubated with inhibitors targeting eNOS (endothelial nitric oxide synthase), iNOS (inducible nitric oxide synthase), nNOS (neuronal nitric oxide synthase) and [Ca2+]i (intracellular Ca2+). The NO concentration in cell culture supernatants was measured during the first 24 h using the Griess test; cellular NO was marked with the fluorescent marker DAF-FM, DA (3-amino, 4-aminomethyl-2',7'-difluorescein; diacetate) and measured by fluorescence microscopy from 1 to 4 h after treatment. eNOS and iNOS mRNA expression levels were measured by quantitative RT-PCR during the first 24 h after treatment. CGRP-induced NO production in the supernatants was high between 1 to 12 h, while cellular NO was highest between 1 to 2 h after treatment and returned to basal levels by 3 h. Both in MG-63 cells and MOBs, the most effective CGRP concentration was 10 nM with a peak time of 1 h. CGRP-induced NO production decreased when eNOS activity was inhibited or when voltage-dependent L-type Ca2+ channels were blocked at 4 h. CGRP was not able to induce changes in iNOS or eNOS mRNA levels and had no effect on the cytokine-induced increase of iNOS expression. Our results suggest that CGRP transiently induces NO production in osteoblasts by elevating intracellular Ca2+ to stimulate the activity of eNOS in vitro.     

Learned or innate production of acoustic signals in fishes: a test using a cyprinid

No information on the inheritance of the ability to produce sounds exists for fishes. In birds, which usually provide extensive post-hatching parental care, acoustic signals are learned in some species but are innate in others. Almost no fishes provide extensive post-hatching parental care and, consequently, the offspring have little opportunity to hear and learn sounds produced by the parents (usually the male in fishes); they may, however, be exposed to acoustic signals of conspecifics in the same habitat. We used a cyprinid, Codoma ornata, to test whether sound production is learned from the parents or whether it is innate. Fertilized eggs of this species were raised in isolation from adults. Upon maturity, these fish were tested for sound production in aggressive and reproductive contexts. Fish which had no contact with adults, and therefore no opportunity to hear the acoustic signals of their species, produced sounds that were similar to those produced by their parents, and they produced these in the same contexts. Significant differences were observed in dominant frequency for one context, with the smaller F₁ fish having signals of higher frequency than parental fish. Since no opportunity for learning existed, this provided evidence that the ability to produce sounds is innate in this minnow species.     

Parturition in the tsetse fly Glossina morsitans: Pattern of activity,sound production and evidence for control by the mother's brain

The mature tsetse larva descends slightly in the uterus causing a protrusion of the female's abdomen and a thrusting open of the female vulva 5–6 h before parturition. Coinciding with larval descent, the female becomes conspicuously restless. The activity pattern monitored by measuring oxygen consumption shows a progression of four discrete stages of activity before and after parturition. Immediately following parturition, the female emits a low frequency sound of 5.8 min duration that differs markedly from sounds produced during feeding or mating. Parturition can be blocked by neck-ligation of the female, thus suggesting a crucial role for the brain. Both neural and hormonal pathways appear to be involved. Transection of the nerve that innervates the uterine muscles reduces the incidence of successful parturition, and parturition in neck-ligated females can be stimulated by transfusion of haemolymph from females that have recently given birth. When parturition is blocked, larvae are retained in utero but eventually pupariate after a delay of 2.3 days.     

A bitter epidemic: The impact of the 1918 influenza on sugar production in Java

Research about the economic consequences of past epidemics has mostly focused on the experience of industrialized countries, thus providing little knowledge about the effects of health shocks on developing economies. We fill this gap by studying the impact of the 1918 influenza in Java, with a new dataset on aggregate food production and district-level figures on (i) sugar production, the major export commodity and the predominant source of labour demand; (ii) agricultural and plantation wages, and (iii) annual crude death rates. The mortality impact of the influenza on Java was high, as crude mortality rates doubled in 1918 relative to the preceding years, but its economic impact was mixed. Aggregate food production did not decline, but sugar output did fall in 1919. Indeed, our regional panel data analysis does not establish a direct relationship between regional epidemic mortality variation and sugar output decline. Instead, we hypothesize that economic activity was rediverted towards food production in order to avoid famine that could have resulted from the combined effects of disrupted shipping at the end of the First World War, climatic conditions and the public health crisis. This is supported by both qualitative observations and quantitative evidence suggesting that those regions that were highly suitable for rice production saw a larger reduction in sugar production, and that in regions that had more flexibility in land tenure arrangements experienced substantially greater reductions in sugar output.     

The medium cycle bioreactor (MCB): Monoclonal antibody production in a new economic production system

The perfusion mode of a continuous cell culture bioreactor was modified to establish a closed loop system. Eighty percent of the spent medium was re-used twice. The medium cycle bioreactor unit was operated sterile and uncomplicated without a technical retention system for the high molecular weight substances. Therefore, only 20% of the actual medium was necessary to run the recycling process. During seven days culture time in a two liter scale 5 grams of IgG₁ type monoclonal antibody was produced. During that period the cell specific productivity was constant. Renewal of proteins was omitted because the protein content in the system persisted at a high level. Therefore, self-conditioning substances of the cells were retained in the system as well as the expensive medium components (proteins with catalytic or stimulating function). Seventy to 80% of medium costs and medium quantity were saved for each medium recycling step. Only cheap metabolites that are consumed by the cells had to be supplemented. Uptake rates of glucose and amino acids were calculated to establish a suitable supplementation mixture for the recirculated medium.     

Whistle variation in Mediterranean common bottlenose dolphin: The role of geographical,anthropogenic, social,and behavioral factors

The studies on the variation of acoustic communication in different species have provided insight that genetics, geographic isolation, and adaptation to ecological and social conditions play important roles in the variability of acoustic signals. The dolphin whistles are communication signals that can vary significantly among and within populations. Although it is known that they are influenced by different environmental and social variables, the factors influencing the variation between populations have received scant attention. In the present study, we investigated the factors associated with the acoustic variability in the whistles of common bottlenose dolphin (Tursiops truncatus), inhabiting two Mediterranean areas (Sardinia and Croatia). We explored which factors, among (a) geographical isolation of populations, (b) different environments in terms of noise and boat presence, and (c) social factors (including group size, behavior, and presence of calves), were associated with whistle characteristics. We first applied a principal component analysis to reduce the number of collinear whistle frequency and temporal characteristics and then generalized linear mixed models on the first two principal components. The study revealed that both geographic distance/isolation and local environment are associated with whistle variations between localities. The prominent differences in the acoustic environments between the two areas, which contributed to the acoustic variability in the first principal component (PC1), were found. The calf's presence and foraging and social behavior were also found to be associated with dolphin whistle variation. The second principal component (PC2) was associated only with locality and group size, showing that longer and more complex tonal sound may facilitate individual recognition and cohesion in social groups. Thus, both social and behavioral context influenced significantly the structure of whistles, and they should be considered when investigating acoustic variability among distant dolphin populations to avoid confounding factors.     

The demographic costs of nectar production in the desert perennial Prosopis glandulosa (Mimosoideae): a modular approach

Nectar production in angiosperms is considered to represent a reproductive cost, and has been associated with a decrease in fruit set or an overall decrease in the energetic budget of the plant. Populations of Prosopis glandulosa var. torreyana (honey mesquite) are a suitable system to evaluate the demographic costs of nectar production, as populations are composed of a 1:1 proportion of nectarful to nectarless individuals. The study was carried out in a population of 404 individuals of Prosopis g1andulosa var. torreyana found in an area with differing water availability in the Southern Chihuahuan Desert. The possible costs of nectar production were assessed on 1212 shoots of the honey mesquite that were tagged in 1994 and followed until 1998. We used two methods of analysis to describe the effect of nectar production on modular population dynamics: matrix analysis and log-xlinear models. Water availability and the varying environmental conditions affected plant growth, but nectar production did not have an effect on the demographic parameters we measured. The values of λ did not differ between nectar morphs and the only important effects we detected were the year to year variation in precipitation and microclimate differences at each site. Furthermore, the elasticity of each demographic process (growth, fecundity, retrogression and stasis) between nectar morphs did not differ. The log-linear models suggested a similar pattern but could discriminate the importance of each factor (nectar morph, year and site) on module fate. We were not able to detect a demographic cost of nectar production in the honey mesquite. The absence of a demographic response could be due to the negligible cost of producing nectar for this species or that the resources allocated for growth are different from those allocated for reproduction. Our results suggest that the modular fates of mesquites are mainly determined by environmental factors. This revised version was published online in August 2006 with corrections to the Cover Date.     

Restricting dairy cow access time to pasture in autumn: The effects on milk production,grazing behaviour and DM intake of late lactation dairy cows

Extending the grazing season in pasture based systems of dairy production can increase farm profitability; poor weather and soil conditions can reduce the number of grazing days. The study objectives were to (i) examine the effect of restricted access to pasture in the autumn on the milk production, grazing behaviour and DM intake (DMI) of late lactation spring-calving dairy cows and (ii) establish the effect of alternating restricted and continuous access to pasture on dairy cow production, DMI and grazing behaviour. Cows were randomly assigned to one of four grazing treatments: (i) 22 h (full-time) access to pasture (22H; control); (ii) Two 5-h periods of access to pasture (2×5H); (iii) Two 3-h periods of access to pasture (2×3H); and (iv) alternating between full-time and 3-h access to pasture with no more than three continuous days on any one regime, e.g. Monday – full-time access, Tuesday − 2x3H access, Wednesday − 2x3H access; Thursday – full-time access, etc. (2×3HV). Restricted access to pasture was offered after a.m. and p.m. milking. Swards of similar quality and pregrazing herbage mass were offered. Treatment had no effect on milk yield (13.2 kg/day), milk fat (48.2 g/kg), protein (39.0 g/kg) or lactose content (42.6 g/kg) and milk solid yield (1.15 kg/day). Similarly, there was no effect of treatment on final BW (483 kg) or final BCS (2.66). There was no significant difference in DMI (15.1 kg DM/cow/day) between treatments. There was an effect on daily grazing time, 22H cows (565 min/cow/day) grazed for longest time, however, when the 2x3HV treatment had full-time access to pasture, they had a similar grazing time (543 min/cow/day) to the 22H cows and were similar to the 2x3H treatment on days with restricted access to pasture (357 min/cow/day). The 22H and 2x5H animals had similar grass DMI/min (29.2 g/min), the 2x3HV were higher (33.9 g/min) but were similar to the comparable treatment when offered 2x3H access time (41.6 g/min) and when offered 22H access time (27.7 g/min). The results from this study show how when offered a grass only diet of autumn pasture grazing behaviour can be modified by restricting pasture access time without reducing dairy cow production in late lactation at low production levels. There was also no effect of alternating access time between 22H and 2x3H on milk production and DMI in the 2x3HV treatment. Restricted access time to pasture in autumn may be a strategy which farmers can use to extend the grazing season.