Isospora petrochelidon sp. n. (Protozoa: Eimeriidae) from the Cliff Swallow, Petrochelidon pyrrhonota

SYNOPSIS. Isospora petrochelidon sp. n. (Protozoa: Eimeriidae) is described from the cliff swallow, Petrochelidon pyrrhonota , from Douglas County, Colorado. Oocysts were passed primarily between 4 and 9 p.m. Sporogony was completed by 24 hr in 3% aqueous potassium dichromate at 21–28 C. The ellipsoid to ovoid oocysts averaged 25.2 × 22.2 μm. The oocyst wall was smooth, colorless, and single-layered. The 2 polar granules were disc-shaped, each adjoining a sporocyst. The lemon-shaped sporocysts averaged 18.4 × 10.8 μm. There was no membrane enclosing the sporocyst residuum and sporozoites. Two fledgling Isospora -free swallows fed sporulated oocysts began passing them on day 4 and died with massive infections on day 5. Data from these birds indicate that schizogony occurred during nighttime hours, gametogony during the day. Endogeny was found throughout the intestine distal to the gizzard, with schizogony confined to the convoluted glands of the subvillar mucosa and gametogony to the villar epithelium. Sporocysts released from mechanically ruptured oocysts excysted in 2% pancreatin within 5 min. Sporulated oocysts fed to a pigeon squab, duckling and cockerel produced no infections.     

Heterophylly in Ranunculus flabellaris: The Effect of Abscisic Acid on Leaf Ultrastructure

Ranunculus flabellaris Rafin., an aquatic buttercup, exhibitsheterophylly at the level of cellular ultrastructure. Comparedto terrestrial leaves, underwater leaves have thinner epidermalcell walls and more numerous paramural bodies per epidermaland mesophyll cell cross-section. The number of chloroplastsand mitochondria in cell cross-sections also contrasts betweenthe two leaf types. Despite within-and between-leaf variations,different patterns of organelle distribution for the two leafforms were found using principal coordinates analysis. In addition,underwater leaf chloroplasts are smaller, have fewer grana,a greater number of thylakoids/granum, and less starch comparedto chloroplasts from terrestrial leaves. At the ultrastructurallevel, submergence in ABA solution does not produce a leaf withas many characteristics of the terrestrial environment, as shownin previous studies of leaf morphology and anatomy. While numberand distribution of organelles in ABA-treated leaves are similarto terrestrial leaves, some features of chloroplast internalstructure and paramural body number and distribution resembleunderwater leaves. It is postulated that ABA acts as a morphogeninvolved in guiding the irreversible processes of leaf development,but certain subcellular characteristics may be determined directlyby the physical environment. Difficulties encountered in quantitativeanalyses of cellular ultrastructure are discussed. Ranunculus flabellaris, ABA, heterophylly, leaf ultrastructure, principal coordinates analysis     

Phenology of nutritional differences between new and mature leaves and its effect on caterpillar growth

Abstract. 1. We determined the phenology of the shrub Spiraea latifolia Ait. Bork. (Rosaceae), which has indeterminate shoot growth, and the effects of phenological changes in leaf quality on growth rate of the early-spring feeding buckmoth caterpillars, Hemileuca lucina Hy. Edw. (Saturniidae).
2. Leaves, regardless of whether they were newly expanded or several weeks old, were tougher later in the growth season (mid-June) than similarly aged leaves collected earlier; correspondingly, water and nitrogen content for leaves of all ages declined through the larval period. By July, newly expanded leaves had no more nitrogen than mature leaves.
3. Relative growth rate of third instar larvae fed new leaves or a mixture of new and mature leaves in early June was higher than that of those fed mature leaves, and efficiency of conversion of digested food to biomass was higher for larvae fed new leaves than for those fed mature leaves or a mixture.
4. In another experiment, larvae were reared on new leaves through the fourth instar and then fed a diet of new, mature or a combination of new and mature leaves, a regimen that was similar to the phenologies of both plants and caterpillars in the field. There was no difference in time to pupation or pupal weights among these treatments.     

Dehydration of Onion Cells: A Comparison of Freezing vs. Desiccation and Living vs. Dead Cells

Measurements were made of the amount of liquid water present in the epidermal cells of onion at various degrees of dehydration caused by slow extracellular freezing and by desiccation. This was achieved by using a pulsed NMR spectrometer during freezing stress and by weighing the epidermal pieces during desiccation. Measurements were made on the extent of cell survival by direct microscopic observation (plasmolysis and protoplasmic streaming). Onion epidermal cells (Allium cepa L. cv. Downing Yellow Globe) were found to survive freezing temperatures as low as –20°C and an equivalent desiccation stress. This equivalence opposes the reports by others on Hordeum vulgare and on Solanum sp. of greater injury by freezing than by an equivalent dehydration due to desiccation. The discrepancy -has been explained in terms of the limitations of the conductivity method used by those authors to evaluate the injury. The freezing and desiccation curves correspond to the equation: L _t=L₀Δt_m/t+L_u where L_t and L₀ are the amounts of liquid water at temperature t and O°C respectively. Δt_m is the freezing point depression of the cell sap and L_u is the amount of liquid water which does not freeze. These results demonstrate that the dehydration of onion cells during both freezing and desiccation duplicates the dehydration of ordinary aqueous solutions. This was equally true for living and dead cells, and suggests that the negative turgor invoked by others is not significantly involved in the dehydration of living Allium cepa epidermis cells. An explanation is proposed for these contradictory results.     

THE DETERMINATION OF THE COLI-AEROGENES CONTENT OF MILK AND DAIRY EQUIPMENT BY PLATING ON VIOLET RED BILE AGAR INCUBATED AT 30°

SUMMARY: Violet red bile agar (VRB) incubated at 30° for 20–24 hr was as good an indicator of coli-aerogenes bacteria in milk as MacConkey's broth. A high proportion (82%) of the large, deep red colonies considered to be formed by coli-aerogenes bacteria were confirmed as such. A British brand of dehydrated VRB agar was as suitable as an American brand of this medium for determining the coli-aerogenes content of milk. All the strains of typical coli-aerogenes bacteria tested formed red colonies. In a small proportion of cases the diameter was less than 0·5 mm. The only other milk bacteria which formed colonies resembling those of coli-aerogenes organisms were some acid forming strains of Gram-negative rods. Coli-aerogenes bacteria, determined on VRB agar at 30°, generally constituted only a small proportion of the microflora of fresh raw milk and of farm dairy equipment.     

Long-Distance Movement of a White-Tailed Deer Away From a Chronic Wasting Disease Area

Abstract: Chronic wasting disease is a fatal, transmissible spongiform encephalopathy found among cervids. Spread of the disease across the landscape is believed to result from movements (dispersal, exploratory, transient, or migratory) of infected deer, serving as the vectors for the disease. We document an unusual long-distance movement of a young female, out of the chronic wasting disease eradication zone in south-central Wisconsin. This type of movement could function as a rapid, long-distance dispersing mechanism for the disease only if the following conditions are met: the deer is infected and shedding prions, the deer directly contacts other deer and transmits secretions carrying an infectious dose of prions, or an infectious dose of prions is transmitted to the environment and taken up by other deer. Despite lower prevalence rates of chronic wasting disease among young deer, we believe managers should not dismiss deer making long-distance movements such as we report, as they could serve as potential long-distance vectors of the disease.     

Chromosome‐specific microsatellites from the tammar wallaby X chromosome and chromosome 2

Microsatellites were identified from fully sequenced bacterial artificial chromosome clones from the X chromosome and chromosome 2 of the tammar wallaby, Macropus eugenii. A total of 20 microsatellites were genotyped. Seven X chromosome loci and eight loci from chromosome 2 were polymorphic, with between two and 11 alleles per locus. These markers will facilitate genetic mapping in the tammar wallaby and will have wider applications in macropod population genetics. In particular, X chromosome microsatellites will provide a novel evolutionary perspective from which to view macropod mating systems and gene flow.