Metabolic rate in diapause and nondiapause brown locust eggs correlated with embryonic development

Insects use dormancy to survive adverse conditions. Brown locust Locustana pardalina (Walk.) eggs offer a convenient model to study dormancy (diapause and quiescence), which contributes to their survival under arid conditions. The metabolic rates of developing nondiapause, diapause and quiescent eggs are compared in the present study using closed‐system respirometry. The embryo becomes committed to continue development and hatch or to enter diapause 6 days after the eggs are placed on moist soil. The metabolic rate of nondiapause eggs increases exponentially until hatching, whereas that of diapause eggs is low and stable. The metabolic rate of diapause laboratory eggs (1.9 ± 0.6 µL CO₂ mg^?1 h^?1) is significantly higher than that of field eggs (0.5 ± 0.3 µL CO₂ mg^?1 h^?1), although the ranges of metabolic rate overlap and the embryos are all in late anatrepsis. The metabolic rate of quiescent eggs is similar to that of diapause eggs but decreases with time. Low metabolic rates during arrested development allow eggs to persist over long periods before hatching.     

SEXUAL DIMORPHISM OF SHELL SHAPE AND GROWTH OF VILLOSA VILLOSA (WRIGHT) AND ELLIPTIO ICTERINA (CONRAD) (BIVALVIA: UNIONIDAE)

Shell shape and growth of two unionacean species, Villosa villosaand Elliptio icterina, are analyzed with univariate and multivariatetechniques. The relationship of shape variables to size variablesis examined. Under the lognormal assumption, parametric testsof these allometric relationships are valid. Variables describingthe ventro-posterior region of the shell are shown to be thebest of those tested for discriminating between the sexes ofboth species regardless of statistical method. Neither speciesexhibits size sexual dimorphism. Shape sexual dimorphism ofV. villosa is constant during adult growth, but the more subtledimorphism of E. icterina changes as adults continue to grow. (Received 20 January 1986;     

TWO TYPES OF SENSORY PANELS OR ARE THERE MORE?

The purpose of this article is to discuss the issues associated with selecting assessors for sensory panels. It develops the argument that although there are many variations in the detail of how assessors are selected, all panels can be considered as either (1) selecting respondents to measure ingredient concentrations via perceptions or (2) selecting respondents to represent the response that would be obtained from a wider consumer population. The validity of the data collected, i.e., the extent to which the data collected measures what was originally intended, depends on the detail of how assessors were selected as well as a number of other factors.     

A histochemical and electrophysiological study of the action of diazoxon on cholinesterase activity and nerve conduction in ganglia of the cockroach Periplaneta americana L

When sixth abdominal or metathoracic ganglia of the cockroach Periplaneta americana L. were irrigated continuously with diazoxon (O, O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphate) solution in situ, the log. of the time required to block conduction in certain nerve pathways in the ganglia was directly proportional to the log. of the concentration of diazoxon applied. Inhibition of cholinesterase began peripherally before function was affected, and had begun to affect the neuropile by the time that conduction was first blocked. Longer exposure to diazoxon disrupted nerve function even more, especially in the sixth abdominal ganglion, and inhibited more cholinesterase, but much longer exposure was needed to inhibit nearly all the cholinesterase. Irrigation with saline, begun when block first occurred, failed to restore completely either nerve function or cholinesterase activity. The cholinesterase activity of ganglia from cockroaches treated topically with an LD90 of diazoxon and examined at intervals after treatment decreased steadily to a level similar to that of ganglia treated directly with diazoxon until conduction was just blocked, but rarely became less, even in moribund insects. Nerve function in metathoracic ganglia became badly affected and remained so in all cockroaches that failed to recover, but sixth abdominal ganglia, though usually badly affected for a time, always recovered normal function, even in prostrate cockroaches. The condition of a poisoned insect, therefore, corresponded much more closely to the functional condition of the metathoracic ganglion than to that of the sixth abdominal ganglion. Applying the insecticide close to a ganglion advanced the time of onset of symptoms but affected the final outcome very little. It was calculated that the highest concentration of diazoxon in the haemo-lymph in contact with the nervous systems of cockroaches treated topically with LDgo's of diazoxon was about 10^-5M.     

The function of the intramaxillary joint in the Round Island boa, Casarea dussumieri

The bolyeriid snakes Casarea dussumieri and Bolyeria multocarinata are unique among vertebrates in possessing an intramaxillary joint that separates the maxilla into anterior and posterior segments. In contrast to previous studies, which suggest that this joint permits enhanced elevation of the anterior maxillary teeth, our films of live Casarea show that the snout and anterior maxillary teeth are actively depressed 15° 20° below rest position through bilateral retraction of the palatomaxillary arches. Patterns of bone movement in living Casarea support the hypothesis that a caudally directed force is transmitted to the snout via the medial bones of the palatomaxillary arch, suggesting functional affinities between Casarea and higher henophidians.
The intramaxillary joint, in conjunction with the curvature of the mandibles, allows the jaws of Casarea to encircle hard, cylindrical prey held transversely in the mouth. Because the Mauritian terrestrial vertebrate fauna lacks mammals and is dominated by skinks and geckos, which Casarea is known to consume, we suggest that the intramaxillary joint functions in a manner analogous to that achieved by quite different maxillary modifications in colubrid scincivores. Although the origin of the bolyeriid intramaxillary joint remains unclear, its structural refinement and evolutionary stability may be due to selection pressures arising from limited prey diversity.     

Attachment and Short-Term Maintenance of Motility and Viability of Entamoeba Histolytica In A Defined Medium*

Organic requirements for attachment to glass, elongation, and motility of Entamoeba histolytica, have been determined. the trophozoite, which has been grown axenically only in highly complex media with reduced oxygen tensions, remains rounded and detached when placed in a Tris-HCl buffered solution containing NaCI, KCI, MgCI₂, and CaCI₂. A maintenance medium in which the amebae could attach to glass, elongate, and remain motile and viable for 12 to 24 h was devised with the addition of cysteine, ascorbic acid, bovine serum albumin, and the vitamin solution of medium NCTC #107. Tris-HCI was the most effective buffer tested and the optimal pH was 6.9 to 7.0. Survival, but not attachment, of the amebae was decreased at osmolalities ranging between 110 and 180 milliosmoles/kg, whereas both functions were decreased above ～260 milliosmoles/kg. Bovine serum albumin, the most effective of the proteins tested, and the vitamin solution helped maintain attachment of some ameba strains, but were not required by other strains. the requirements for cysteine and ascorbic acid were absolute and highly specific. During incubation in the maintenance medium, cell volumes decreased. Sensitivity of the organisms to agglutination by concanavalin A, wheat germ agglutinin, soybean agglutinin and fucose binding protein remained unchanged.     

Niche segregation and genetic structure of Campylobacter jejuni populations from wild and agricultural host species

Bacterial populations can display high levels of genetic structuring but the forces that influence this are incompletely understood. Here, by combining modelling approaches with multilocus sequence data for the zoonotic pathogen Campylobacter, we investigated how ecological factors such as niche (host) separation relate to population structure. We analysed seven housekeeping genes from published C. jejuni and C. coli isolate collections from a range of food and wild animal sources as well as abiotic environments. By reconstructing genetic structure and the patterns of ancestry, we quantified C. jejuni host association, inferred ancestral populations, investigated genetic admixture in different hosts and determined the host origin of recombinant C. jejuni alleles found in hybrid C. coli lineages. Phylogenetically distinct C. jejuni lineages were associated with phylogenetically distinct wild birds. However, in the farm environment, phylogenetically distant host animals shared several C. jejuni lineages that could not be segregated according to host origin using these analyses. Furthermore, of the introgressed C. jejuni alleles found in C. coli lineages, 73% were attributed to genotypes associated with food animals. Our results are consistent with an evolutionary scenario where distinct Campylobacter lineages are associated with different host species but the ecological factors that maintain this are different in domestic animals such that phylogenetically distant animals can harbour closely related strains.     

Estimation of Occupied and Unoccupied Black-Tailed Prairie Dog Colony Acreage in Colorado

Abstract: Black-tailed prairie dogs (Cynomys ludovicianus) are a species of concern and accurate estimates of occupied area are required to assess their status. We conducted aerial line-intercept surveys to estimate colony areas in Colorado, USA, 2006–2007. Optimal allocation based on results from a previous (2002) survey was used to distribute flight time to sample 28 counties. Uncorrected estimates of active and inactive colony areas from the aerial surveys were 329,529 (SE=16,841) ha and 18,292 (SE=2,366) ha, respectively. We attempted to ground-truth a randomly selected sample of 186 colony intercepts but gained complete access to only 150. Ground-truthing demonstrated that aerial surveys estimated only 96% of the true lengths of colony intercepts but overestimated the proportion of active colonies. Corrected estimates of active and inactive colony areas are 319,165 (SE = 20,105) ha and 42,422 (SE = 11,485) ha, respectively. Because ground-truthing was not conducted in the original 2002 survey, uncorrected estimates from this survey are the appropriate metric to be used for comparison to the 2002 data. Our estimates demonstrated a 29% increase (SE = 6.3) in area occupied since surveys were conducted in 2002. These results are useful to state and federal agencies and other conservation partners in determining the condition of the species when conducting status reviews.     

Effects of experimental warming on survival,phenology, and morphology of an aquatic insect (Odonata)

1. Organisms can respond to changing climatic conditions in multiple ways including changes in phenology, body size or morphology, and range shifts. Understanding how developmental temperatures affect insect life‐history timing and morphology is crucial because body size and morphology affect multiple aspects of life history, including dispersal ability, whereas phenology can shape population performance and community interactions. 2. It was experimentally assessed how developmental temperatures experienced by aquatic larvae affected survival, phenology, and adult morphology of dragonflies [Pachydiplax longipennis (Burmeister)]. Larvae were reared under three environmental temperatures: ambient, +2.5, and +5 °C, corresponding to temperature projections for our study area 50 and 100 years in the future, respectively. Experimental temperature treatments tracked naturally‐occurring variation. 3. Clear effects of temperature were found in the rearing environment on survival and phenology: dragonflies reared at the highest temperatures had the lowest survival rates and emerged from the larval stage approximately 3 weeks earlier than animals reared at ambient temperatures. There was no effect of rearing temperature on overall body size. Although neither the relative wing nor thorax size was affected by warming, a non‐significant trend towards an interaction between sex and warming in relative thorax size suggests that males may be more sensitive to warming than females, a pattern that should be investigated further. 4. Warming strongly affected survival in the larval stage and the phenology of adult emergence. Understanding how warming in the developmental environment affects later life‐history stages is critical to interpreting the consequences of warming for organismal performance.     

The Welsh pantothere Kuehneotherium praecursoris

A new genus and species of pantothere ( Kuehneotherium praecursoris ) from the Welsh Rhaetic is defined, named and briefly described. Its molars are tritubercular, with a lingual cingulum in the uppers and a tiny talonid with a large hypoconulid in the lowers. The molars and premolars do not appear to intergrade. There were between nine and eleven lower posteanines; at least five of these were premolars. The number of upper postcanines is unknown; it is unlikely to have differed by more than one from the number of lowers. The dentary terminated in a, well-developed condyle, there was no angle, and there is evidence of a full complement of accessory jaw bones including a coronoid. A new family Kuehneotheriidae is established for Kuehneotherium and related forms. The pantotheres are divided among three suborders: the new suborder Amphitheria, which includes the families Kuehneotheriidae, Amphitheriidae, Peramuridae and Paurodontidae; the Dryolestoidea and the Symmetrodonta.