Effects of temperature on the development,growth, and survival of larvae and pupae of a north-temperate chrysomelid beetle

Summary Developoment, growth, and survival of larvae and pupae of the red turnip beetle, Entomoscelis americana Brown, were studied in 10 constant and four alternating temperature regimes (10 to 32.5° C), in field-cages, and in natural populations in Manitoba. This beetle has a northtemperate distribution in North America. Larval and pupal development occurs in spring and normally is completed before the end of June. Growth and development occurred at all constant temperatures tested, but survival was low at the extreme temperatures. Therefore, the threshold and upper limit were near 10 and 32.5° C. The developmental times of the sexes did not differ and decreased with temperature, except possibly at 32.5° C. The average weight of adult females increased with temperature up to 32.5° C and those of males up to 25° C. Considering developmental rate, survival, adult weight, and incidence of malformed adults, the optimum temperature was estimated to be near 27.5° C.Development was accelerated significantly (6 to 9%) in alternating regimes with temperatures differing by 10° C, but not in regimes differing by 5 and 15° C. All alternating regimes increased adult weight, 5 to 17% for females and 2 to 10% for males. Field cage studies confirmed the increase in adult weight, but not the acceleration in development.A three-parameter normal function described accurately the relationship between developmental rate and constant temperature. A computer simulation model based on this equation estimated developmental times in field cages to within one to five days. For natural populations the model overestimated the developmental times by five to 16 days. The discrepancies between model estimates and observed developmental times in natural populations apparently were due to the elevation of larval and pupal body temperatures above air temperatures by behavioral thermoregulation. The elevation of body temperature was estimated to be equivalent to the addition of 5 to 6° C to the maximum daily air temperature. The adaptations and responses of this beetle to the cool spring temperatures of the north-temperate region are discussed.Contribution No. 1164, Agriculture Canada, Research Station, Winnipeg, Manitoba, Canada     

Characteristics of the relative maximum in the decay of delayed light emission from Pothos leaf following far-red excitation

Following illumination with wavelengths longer than 700 nm, the intensity of light emission from Pothos aurea leaf falls for 1 min and then increases to a maximum after 2 min in the dark. The spectrum of this minute-range liminescence matches that of prompt fluorescence excited at the same wavelength, but differs from that of prompt or minute-range delayed emission excited by wavelengths shorter than 700 nm. This emission is less sensitive to heat damage than millisecond delayed emission, and may originate from photosystem I.     

Enzyme kinetics of a highly purified mitochondrial creatine kinase in comparison with cytosolic forms

Summary Mitochondrial creatine kinase (CK) purified from canine myocardium showed a single protein band on SDS-PAGE and was free of MMCK. Its amino acid composition was different than MMCK or BBCK and did not react to antiserum to MMCK or BBCK. Using purified mitochondrial, MM and BBCK, the velocity of reaction (V) was estimated for creatine phosphate (CP), creatine (C), adenosine triphosphate (ATP) and adenosine diphosphate (ADP) over a wide range of concentrations including those at V_max. The values for K_m (mM/L) derived from Lineweaver-Burke plots are shown: The affinity of mitochondrial CK for C is much greater than MMCK which is compatible with the energy shuttle hypothesis, namely ATP is converted by mitochondrial CK to CP, and then diffuses to the myofibril for conversion to ATP for utilization.     

Management of localized non-Hodgkin's lymphoma

Non-Hodgkin''s lymphomas (NHLs) are a heterogeneous group of disorders that vary widely in response to therapy. In Canada the modified Rappaport classification is used to categorize NHL. To facilitate the reporting and comparison of treatment results all cases should also be categorized in the terminology of the National Cancer Institute''s working formulation. The choice of therapy should be guided by specific prognostic factors: stage and bulk of the disease, patient''s age, presence of systemic symptoms and histologic subtype. Of these, the last appears to be the most important. Radiotherapy (RT) is the treatment of choice in localized low-grade lymphomas with favourable prognoses, while bimodal therapy (RT and chemotherapy [CT]) is warranted in presentations with unfavourable prognoses. Regional irradiation alone is indicated in intermediate-grade lymphomas with good prognoses (i.e., pathological stage I or II or clinical stage IA or IIA localized disease of small bulk in young patients). All other patients require CT followed by RT. The results of CT alone are encouraging but remain experimental. Aggressive therapy with multidrug regimens that include central nervous system prophylaxis is the foundation for successful treatment of high-grade NHL such as lymphoblastic lymphoma and diffuse small-noncleaved-cell lymphomas. Low-dose RT should be given to sites of bulky disease.     

A new spring for plant cell biology: microtubules as dynamic helices

Cortical microtubules wind around plant cells describing flat, medium or steeply pitched helices. Experiments now suggest that these arrays are dynamically interconvertible — providing a spring-like device that is sensitive to environmental cues and shifts the axis of cell expansion through 90°.     

Characteristics of bacterium GB-2, a presumptiveCytophaga species with novel immunoregulatory properties

A Gram-negative, psychrophilic bacterium, designated GB-2, was isolated from fetal calf serum and analyzed for its morphological, physiological, and biochemical characteristics. Gliding motility, sensitivity to actinomycin D, the presence of the pigment flexirubin and cytochrome c, growth on a variety of carbohydrates, the production of acid fermentation products, and a 34.9 mol% guanine+cytosine (G+C) content of bacterial DNA indicate GB-2 to be a member either of the generaCytophaga orFlexibacter. Growth of GB-2 was optimized in a simple defined medium to facilitate isolation and characterization of bacterial products. Liquid growth of GB-2 resulted in the release of significant quantities of a macromolecule free of both endotoxin and protein into the growth supernatant, which activated the proliferation of murine lymphocytes. The relationship between this bacterium and its end-products to other species of theCytophaga/Flexibacter group is discussed.     

Effects of fructose on human fibroblast metabolism: the application of DNA measurements as a basis for interpretation

Summary A fluorometric procedure for measuring DNA was used to study growth and metabolic responses of eight cell strains of human foreskin fibroblasts. In preliminary studies this procedure gave more precise specific activity changes inN-acetyl-β-d-glucosaminidase (NAG) than did a protein activity basis, when changes in this enzyme's specific activity were investigated as a function of experimental cell manipulation. When fibroblast growth in eight cell strains was compared in 134 mM d-fructose vs. 13.4 mM glucose-supplemented minimum essential media, a significant increase in cellular DNA (50%) and protein (45%) occurred over an 11-d period. No significant differences in media pH change, lactate production, or carbohydrate uptake occurred on a DNA basis when cell metabolism was compared over the last 24 h of culture in the two media. Cells grown in fructose-containing media tended to show a reduction in NAG specific activity when compared with those grown in glucose-containing media.     

The diets of Hispaniolan colubrid snakes

Summary Approximately 1590 Hispaniolan colubrid snakes representing six genera and eight species were examined for prey remains (Alsophis cantherigerus, Antillophis parvifrons, Darlingtonia haetiana, Hypsirhynchus ferox, Ialtris dorsalis, Uromacer catesbyi, U. frenatus, and U. oxyrhynchus). The snakes were collected at many localities over a span of 80 years.Of 426 prey items, 77.9% were lizards (of which 69.6% were anoles), 19% frogs, 2.6% birds and mammals, and 0.5% other snakes. Darlingtonia was the only snake that did not exploit lizards; it fed exclusively on Eleutherodactylus frogs, including egg clutches. Disregarding Darlingtonia, there is no size class of Hispaniolan colubrids between 20–90 cm SVL that does not prey primarily on Anolis. Certain prey genera are added to, or deleted from, diets depending on snake size, but the data suggest that snake SVL alone does little to dictate what prey genera (or groups) are eaten. Shannon-Wiener values (H') indicate that Darlingtonia has the narrowest trophic niche, while Alsophis and Ialtris have the widest. Values of H' are not correlated with snake SVL, but highly significant (P<0.001) correlations exist between H' and mid-body circumference, head width, and snout width, and these characters may be indicators of trophic generalists and specialists. Anolis lizards are the most ubiquitous and conspicuous vertebrates on Hispaniola, and it is not surprising that they are widely exploited as a food source. Although as some snake species grow larger, anoles play a decreasingly important role in their diets, there is no evidence to suggest that they are ever abandoned as a food source by any Hispaniolan colubrid of any size.Secretive lizards of low vagility are eaten almost exclusively by wide ranging foragers (Alsophis, Antillophis); very active prey (Ameiva) is taken by sit-and-wait strategists (Hysirhynchus, U. frenatus). Those snakes which exploit the most prey groups are active foragers. Uromacer catesbyi exhibits both foraging modes, and predictably, eats diurnally active (anoles) and diurnally quiescent (hylid frogs) prey with almost equal frequency.Within Maglio's cantherigerus species assemblage, in which an Alsophis cantherigerus-like snake was ancestral to the other species, and in which longsnouted Uromacer are the most morphologically derived, there is an obvious trend toward trophic specialization on Hispaniola. The West Indies have provided an ideal natural laboratory for the investigation of many aspects of vertebrate ecology, and an arena in which to test theories of island biogeography. The most extensively studied West Indian vertebrates have been the lizards of the iguanid genus Anolis. Conversely, the ecology of West Indian snakes has been largely ignored. This is surprising in light of the fact that much has been written about Anolis predation, but little has been written about predators of Anolis; snakes may be important, frequent consumers of anoles.Hispaniola is physiographically and ecologically the most diverse of the Greater Antilles and, concomitantly, it has the most diverse snake fauna, including six colubrid genera containing 11 described species. It has rich frog and lizard faunas, but only two endemic mammals. Study of the diets of Hispaniola's colubrid snakes was undertaken to gain initial insights into the ecology of the snakes and to determine 1) what the snakes eat; 2) what relationships exist between snake diet and snake size as well as head and body proportions; 3) what relationships exist between snake foraging mode and prey type and size; 4) if anoles, as the most ubiquitous and conspicuous vertebrates on Hispaniola, comprise an important source of food; 5) if significant geographical differences in diet exist, expecially on satellite islands; 6) if north island and south island (sensu Williams 1961) Anolis ecomorphs are preyed upon by the same snake species in similar proportions; 7) if snakes are selective or opportunistic predators.This paper, the first in a series that will address all of the above topics, will briefly describe methods, snake species and prey genera. Prey genera are analyzed in terms of what snake taxa prey upon them, what size classes of snakes prey upon them, and prey genera diversity versus snake size and proportions.