Aggregata dobelli N. Sp. and Aggregata millerorum N. Sp. (Apicomplexa: Aggregatidae) from Two Species of Octopus (Mollusca: Octopodidae) from the Eastern North Pacific Ocean

ABSTRACT. Gamogony and sporogony of two new species of Aggregata (Apicomplexa: Aggregatidae) commonly were observed during histopathological examination of the digestive tracts of octopuses from the National Aquarium in Baltimore. North Pacific giant octopus, Octopus dofleini martini Pickford 1964, from British Columbia and Washington state were infected with Aggregata dobelli n. sp. Sporocysts were smooth-surfaced, dark-staining, subspherical to subovoid, typically 18–31 μ m long by 15–27 μ m wide, and contained 9–22 sporozoites, 18–23 μ m long. California two-spotted octopus, Octopus bimaculoides Pickford and McConnaughey 1949, from California were infected with Aggregata millerorum n. sp. Sporocysts were smooth-surfaced, dark-staining, and subspherical to subovoid, 12–20 μ m long by 11–17 μ m wide, and contained 8–10 sporozoites, 18–31 μ m long. Both species infected the noncuticularized spiral caecum and intestine; A. millerorum n. sp. also infected the cuticularized esophagus and crop. Both parasites were present in the submucosa, muscularis, and serosa. Our observations of Aggregata infections in cuticularized regions of the gut and in the muscularis and serosa appear to be novel. Associated pathologic features included hypertrophy of invaded cells, edema, inflammation, and ulceration.     

Photosynthesis in frost-hardened and frost-stressed leaves of Hedera helix L.

Abstract The purpose of this study was to determine the respective extents to which winter reduction of photosynthetic capacity in ivy (Hedera helix L.) is caused by direct frost injury to the photosynthetic apparatus and by preceding protoplasmic changes connected with the acquisition of frost tolerance. Potted juvenile ivy plants were placed in the open under natural weather conditions whilst others were hardened under controlled conditions and subjected to the desired frost stress. Low non-freezing temperatures induced frost tolerance in ivy leaves down to about – 12°C (50% injury = TL₅₀) without impairing net photosynthetic rate as measured under standard conditions (20°C, light saturation, natural CO₂ level; = Standard-F_n. Only if the leaves froze (below ? 3°C to ?4°C) was a reversible inhibition of Standard-F_n observed. As long as the temperatures did not fall below approximately ?8°C the inhibition was small and Standard-F_n reached about 80–90% of the control. In this case the stomatal opening narrowed, giving a poorer supply of CO₂ to the mesophyll cells. Maximal frost tolerance (TL_5O?20°C to ?24°C) developed only with severe frosts below about ? 10°C. After such frosts, Standard-F_n was reduced to less than 20% of the control. The dependence of the rate of net photosynthesis on the internal CO₂ concentration showed a lower initial slope, thus indicating disturbances of chloroplast functions. However, neither in outdoor plants nor in those artificially frosted at – 20°C could there be found an appreciable inhibition of the electron transport capacity from H₂O to dichlorophenol indophenol or of ribulose bisphosphate carboxylase. If intact, severely frosted ivy plants were then held at higher temperatures (20/15°C), Standard-F_n recovered completely in approximately 10 d. Furthermore, following a frost period with temperatures down to ?12°C, mild weather caused a distinct improvement in Standard-F_n in outdoor plants, and there was no loss of maximum frost tolerance. Thus it can be concluded that the inhibition of Standard-F_n after severe frosts is not due to the development of maximal frost tolerance, but rather may be attributed to frost damage to the photosynthetic apparatus.     

Multiple Pleistocene refugia and Holocene range expansion of an abundant southwestern American desert plant species (Melampodium leucanthum,Asteraceae)

Pleistocene climatic fluctuations had major impacts on desert biota in southwestern North America. During cooler and wetter periods, drought‐adapted species were isolated into refugia, in contrast to expansion of their ranges during the massive aridification in the Holocene. Here, we use Melampodium leucanthum (Asteraceae), a species of the North American desert and semi‐desert regions, to investigate the impact of major aridification in southwestern North America on phylogeography and evolution in a widespread and abundant drought‐adapted plant species. The evidence for three separate Pleistocene refugia at different time levels suggests that this species responded to the Quaternary climatic oscillations in a cyclic manner. In the Holocene, once differentiated lineages came into secondary contact and intermixed, but these range expansions did not follow the eastwardly progressing aridification, but instead occurred independently out of separate Pleistocene refugia. As found in other desert biota, the Continental Divide has acted as a major migration barrier for M. leucanthum since the Pleistocene. Despite being geographically restricted to the eastern part of the species’ distribution, autotetraploids in M. leucanthum originated multiple times and do not form a genetically cohesive group.     

Wittmannia antarctica N. G., N. Sp. (Nosematidae), a New Hyperparasite in the Antarctic Dicyemid Mesozoan Kantharella antarctica

ABSTRACT. Collections of the dicyemid mesozoan Kantharella antarctica were made in the Weddell Sea during the Antarctic Expedition of the research vessel RV Polarstern in 1990 and 1991. A diplokaryotic microsporidian was found infecting all nematogens from all the samples taken in both years. The infected cells contained all developmental stages. Merogony initially was monokaryotic and spoorogony of diplokaryotic sporonts was by multiple fission. The stained ovoidal spores measured between 4.3-6 μm X 1.7-2.3 μm. The ultrastructural findings come from 11 specimens of Kantharella antarctica that were cut in serial sections. All developmental stages were noteworthy because of the myelinosomes situated adjacent to each diplokaryon. Similarly conspicuous were some organelles in the spore: a prominent, extraordinarily electron dense anterior portion of the polaroplast and the posterior vacuole. The isofilar polar filament with a diameter of about 115 nm showed 9-11 coils. The great number of empty spore cases together with an extruded polar filament are indicative of an autoinfection. Though these characteristics resemble in part those of the genus Nosema from the family Nosematidae, the species in Kantharella antarctica differs from the former by its unusual development, life cycle and unusual host. Thus, this new species has been placed in a new genus and the name Wittmannia antarctica proposed.     

Pepino mosaic virus, a new potexvirus from pepino (Solanum muricatum)

Pepino mosaic virus (PepMV), a previously undescribed virus, was found in fields of pepino (Solanum muricatum) in the Canete valley in coastal Peru. PepMV was transmitted by inoculation of sap to 32 species from three families out of 47 species from nine families tested. It caused a yellow mosaic in young leaves of pepino and either a mild mosaic or symptomless infection in 12 wild potato species, five potato cultivars and potato clone USDA 41956 but S. stoloniferum and potato cultivars Merpata and Revolucion reacted with severe systemic necrotic symptoms. The virus was transmitted by plant contact but not by Myzus persicae. It was best propagated and assayed in Nicotiana glutinosa. Sap from infected N. glutinosa was infective after dilution to 10^-1 but not 10^-6, after 10 min at 65°C but not 70°C and after 3 months at 20°C. PepMV had filamentous particles with a normal length of 508 nm; the ends of some seemed damaged. Ultra-thin sections of infected leaves of N. glutinosa revealed many inclusions containing arrays of virus-like particles some of which were banded or whorled; small aggregates of virus-like particles were also common. The virus was purified by extracting sap from infected leaves in a solution containing 0·065 M disodium tetraborate, 0·435 M boric acid, 0·2% ascorbic acid and 0·2% sodium sulphite at pH 7·8, adding silver nitrate solution to the extract, and precipitating the virus with polyethylene glycol followed by two cycles of differential centrifugation. Particles of PepMV normally yielded two proteins with molecular weights of 26 600 and 23 200, but virus obtained from infective sap aged overnight yielded only the smaller protein suggesting that it was a product of degradation of the larger one. The virus is serologically related to two potexviruses, narcissus mosaic and cactus X and its properties are typical of the potexvirus group.     

EARLY STAGES OF THE ENCAPSULATED DEVELOPMENT OF NUCELLA LAPILLUS (LINNAEUS) (GASTROPODA, MURICIDAE)

The intertidal muricid gastropod Nucella lapillus (Linnaeus)develops entirely within an egg capsule up to the juvenile stage.This study investigates how the embryos have adapted to theabundance of their own yolk (protolecith) and extraembryonicnutrients (nurse eggs, capsule fluid) during five stages ofearly organogenesis The pretorsional preveliger uses protolecith and albumen asnutritive resources. The main portion of the protolecith isstored in the large unequal macro-mere 4D, which is interpretedto be an adaptation to the large content of its own yolk andpersists beyond the ingestion stage. The transitory storageof protolecith makes the predominant resorption of the nutritiveeggs possible. The stomodaeum develops early as an ectodermalinvagination and opens into an anterior buccal part and a posterioroesophageal part. The radular sac is of early pretorsional origin.Some prospective endodermal structures (midgut and hindgut)first become apparent by their histological differentiation During ingestion the differentiation of midgut and cephalopodiumis arrested. The extremely thin epithelium of the midgut surroundsthe swallowed nurse eggs The last stage, an early veliger, has developed all essentialorgans as rudiments, except the coelomic derivates and the pallia]organs. The hindgut opens by a proctodaeal invagination (anus).The embryo undergoes further torsional displacement (Received 20 August 1987;     

Establishment,Maintenance, and Integration Mechanisms of Endosymbionts in Protozoa1

ABSTRACT. Important progress has been made in recent years towards better understanding of the establishment and maintenance of endosymbiosis in protozoa and of the eventual integrative mechanisms involved. Still, many problems remain to be investigated more thoroughly. In this paper, while treating and reviewing the subject broadly, particular and more detailed attention is given to three selected systems: endonuclear symbiosis by Holospora bacteria in Paramecium; algal (Chlorella) relationships with the “green”Paramecium (P. bursaria) as host; and the rod-shaped bacteria found in the cytoplasm of Amoeba proteus. Data concerning the physiology of food vacuoles, membrane transport, photobehavior, recognition specificity, enzyme activity, and the like are presented and reviewed and discussed in light of the growing literature on the overall subject of “endocytobiology.” Emphasized is the complicated network of interactions between symbiotic partners and the importance of the development of integrative mechanisms in the evolution of the many intimate associations known at the cellular level today.     

Effect of human odours and positioning of CO2 release point on trap catches of the malaria mosquito Anopheles gambiae sensu stricto in an olfactometer

Abstract.  The anthropophilic malaria mosquito Anopheles gambiae sensu stricto responds to CO₂ and human skin emanations. How these odorants affect the behaviour of this mosquito species is studied in an olfactometer. Carbon dioxide is released either as an homogeneous plume or in a turbulent fashion at two different positions from the trap entrance. Anopheles gambiae is deterred from entering a trap with CO₂ as the only kairomone, when presented as an homogeneous or turbulent plume. This effect is completely overcome by the addition of skin emanations to the CO₂ plume, with a high proportion of mosquitoes found in the trap with skin emanations. Rearrangement of the position of the turbulent CO₂ source so that it is 5 cm downwind of the trap entrance overcomes the deterrent effect of CO₂. Carbon dioxide alone, however, does not elicit higher proportions caught compared with clean air. Further studies with the CO₂ source positioned 5 cm downwind of the trap entrance show that skin emanations alone result in fewer mosquitoes entering the trap than CO₂+ skin emanations. Skin emanations induce more mosquitoes to fly into a trap than a synthetic blend of NH₃+ l-lactic acid when both are combined with CO₂. It is concluded that CO₂ is a poor kairomone when offered alone and that its presence in the plume at the trap entrance deters mosquitoes from entering. By contrast, when positioned just downwind of the trap entrance, CO₂ appears to guide mosquitoes to the vicinity of the trap, where skin emanations then become the principle attractant, causing the mosquito trap entry response. The results of the study have implications for the design of odour-baited traps for this mosquito species.     

How did an annual plant react to Pleistocene glaciations? Postglacial history of Rhinanthus angustifolius in Europe

The impact of climate fluctuations during the Pleistocene on the geographic structure of genetic variation in plant populations is well documented, but there is a lack of studies of annual species at the European scale. The present study aimed to infer the history of the widespread European annual Rhinanthus angustifolius C. C. Gmelin (Orobanchaceae). We explored variation in chloroplast DNA (cpDNA) sequences and amplified fragment length polymorphism (AFLP) in twenty-nine populations covering the entire distribution area of the species. Five AFLP groups were identified, suggesting at least two glacial refugial areas: one area in southwestern Europe and one large eastern area in the Balkan/Caucasus. Recolonization of previously glaciated areas mainly took place from the east of Europe. Despite the difference in life-history traits, the patterns found for the annual R. angustifolius show similarities with those of perennial species in terms of genetic diversity and geographic organization of genetic variation. Although organelle markers have typically been preferred in phylogeographic studies, the cpDNA variation in R. angustifolius did not show any clear geographic structure. The absence of geographic structure in the cpDNA variation may reflect persistence of ancestral polymorphisms or hybridization and introgression with closely-related species.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 1–13.