Monoterpenes emitted by the large pine weevil, Hylobius abietis (L.) feeding on Scots pine, Pinus sylvestris L.

Abstract. Attraction of the large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae) to pine logs was enhanced by the presence of weevils already on the logs. We investigated the volatiles emitted by insects feeding on host trees to determine the mechanism of the attraction. Chemical analyses of the collected volatiles showed large amounts of monoterpenes. There were no qualitative differences in the collections, between Scots pine alone and pine plus feeding weevils, nor between males and females, mated or virgin. Strong quantitative differences in monoterpenes existed that were correlated to the surface of cut bark. Electroantennograms (EAGs) were recorded on male and female antennae stimulated by increasing doses of collected volatiles. EAGs for pine alone and pine plus weevils at the same stimulus loading in (a + P)-pinene gave superimposable curves. EAGs of male and female volatiles were also identical. These results suggest an attraction mediated by host plant allelochemicals rather than by an aggregation pheromone.     

Garden Warbler Sylvia borin migration in sub-Saharan West Africa: phenology and body mass changes

The Garden Warbler is a classic subject for the study of Palaearctic–African bird migration strategies. Most studies have considered the situation close to the breeding areas, while the African and especially the sub‐Saharan part of the species’ migration have received comparatively little attention. Here we use autumn and spring ringing data from Nigeria and The Gambia to study the movements and energetics of the species in West Africa during the non‐breeding season. The first Garden Warblers arrive south of the desert around the beginning of September, roughly at the same time as the median date for their passage through the Baltic Sea region and c. 3 weeks before their median passage date through southern Italy. In the Nigerian Sahel savannahs, where, owing to the rainy season and its associated increase in food availability, many more Garden Warblers stop over in autumn than in the dry spring, the median date of passage is 1 October. The body mass on arrival south of the desert is normally only a few grams more than the lean body mass (LBM; 15 g) – with a mean of 16.6 g (sd = ±1.8 g) in The Gambia and 17.4 g (sd = ±1.8 g) in the Nigerian Sahel. After resting and refuelling in the Sahel, Sudan and Guinea‐type savannahs the Garden Warblers depart during November–December for wintering areas further south. Before leaving, they again increase their body mass, with an average fuel load of c. 20%, and often more than 50% relative to LBM. Some of the birds passing through Nigeria probably spend midwinter around the Congo Basin. During spring they return northwards to the Guinea savannah zone in April and fuel‐up there for the trans‐Sahara passage. At this time they normally increase their body reserves to around 50% of the LBM, but c. 10% of the birds gain 100%, thus doubling their mass. The passage there peaks around 20 April and continues well into May. That the main take‐off northwards is directly from the Guinea savannahs is indicated by the very low numbers trapped in the Sahel during spring.     

NEOSELACHIAN SHARK AND RAY TEETH FROM THE VALANGINIAN, LOWER CRETACEOUS, OF WĄWAŁ, CENTRAL POLAND

Abstract:  Valanginian strata at Wąwał in central Poland have yielded the oldest marine neoselachian assemblages from the Cretaceous of Europe. The faunas comprise seven taxa including Heterodontus polonicus sp. nov., an indeterminate orectolobiform, Protolamna sp., Palaeoscyllium sp., Synechodus nitidus , Squatina cranei and Belemnobatis sp. Heterodontus polonicus is recognized primarily by the high amount of reticulate ornamentation on the lower labial side of the anterior teeth. The faunas from Wąwał are numerically dominated by neoselachian genera such as Synechodus , Heterodontus and Belemnobatis that were already well established in the Jurassic. More modern taxa include the oldest recorded occurrence of the true Squatina -lineage, and the presence of Protolamna is one of the earliest undoubted lamniform occurrences so far reported.     

Combined effects of water column nitrate enrichment, sediment type and irradiance on growth and foliar nutrient concentrations of Potamogeton alpinus

1. High water column NO₃^? concentrations, low light availability and anoxic, muddy sediments are hypothesised to be key factors hampering growth of rooted submerged plants in shallow, eutrophic fresh water systems. In this study, the relative roles and interacting effects of these potential stressors on survival, growth, allocation of biomass and foliar nutrient concentrations of Potamogeton alpinus were determined in a mesocosm experiment using contrasting values of each factor (500 versus 0 μmol L^?1 NO₃^?; low irradiance, corresponding to the eutrophic environment, versus ambient irradiance; and muddy versus sandy sediment). 2. Low irradiance, high NO₃^? and sandy sediment led to reduced growth. In a muddy sediment, plants had lower root : shoot ratios than in a sandy sediment. 3. Growth at high NO₃^? and on the sandy sediment resulted in lower foliar N and C concentrations than in the contrasting treatments. The C : N ratio was higher at high NO₃^? and on the sandy sediment. Foliar P was higher on the muddy than on the sandy sediment but was not affected by irradiance or NO₃^?. The N : P ratio was lowest at high NO₃^? on the sandy sediment. 4. Total foliar free amino acid concentration was lowest on sand, low irradiance and high NO₃^?. Total free amino acid concentration and growth were not correlated. 5. Turbidity and ortho‐PO₄^3? concentration of the water layer were lower at high water column NO₃^? indicating that the growth reduction was not associated with increased algal growth but that physiological mechanisms were involved. 6. We conclude that high water column NO₃^? concentrations can significantly reduce the growth of ammonium preferring rooted submerged species such as P. alpinus, particularly on sediments with a relatively low nutrient availability. Further experiments are needed to assess potential negative effects on other species and to further elucidate the underlying physiological mechanisms.     

Ultrastructural Observations on the Infection of Rat Liver by Plasmodium berghei Sporozoites In Vivo1

The invasion of liver parenchymal cells by sporozoites of Plasmodium berghei Vincke & Lips, 1948, was studied in vivo using transmission electron microscopy. Livers of Brown Norway rats were examined 30 and 60 min after intraportal injection of 15 million sporozoites each. Sporozoites found after incorporation into vacuoles in hepatocytes were often located near a bile canaliculus at the lateral cell surface, surrounded by hepatocyte lysosomal structures; however, degradation of sporozoites caused by lysosomal digestion inside hepatocytes was never observed. Due to the crescent shape of sporozoites, serial sections were necessary to demonstrate the actual process of invasion of the hepatocyte. The hepatocyte's plasmalemma appeared to invaginate due to the sporozoite's action, thereby creating a parasitophorous vacuole. It was suggested that the sporozoite actively penetrated the hepatocyte; however, no visible depletion of rhoptries and micronemes was observed.     

Tryptophan Decarboxylase Activity in Developing Cucumber Seedlings

The rate of decarboxylation of DL-tryptophan-carboxyl-¹⁴C in homogenates of cotyledons, hypocotyls and roots of sterile and non-sterile cucumber seedlings of 4, 8 and 11 days was measured. Tryptophan decarboxylating activity is highest in hypocotyls, lowest in cotyledons. In all organs the activity decreases with age. This enzyme activity does not parallel the IAA level in the organs during ageing.     

Three-Dimensional Reconstruction of Rabbit-Derived Pneumocystis carinii from Serial-Thin Sections II: Intermediate Precyst

Three-dimensional reconstruction of a binucleate intermediate precyst of Pneumocystis carinii was performed from serial-thin sections using the CATIA (Conception Assistée Tridimensionnelle Inter Active) Dassault system program. The presence of a mitochondrion, complex well-developed endoplasmic structures, and numerous Golgi vesicles was established. A better understanding of the ultrastructure of rabbit-derived P. carinii stages made it possible to formulate hypotheses on the evolution and physiology of the endomembrane system. Thus, the presence of the well-developed endoplasmic saccular structure and more than 230 Golgi vesicles in its vicinity might be implicated in the differentiation of the parasite surface structures and might also be related to nuclear division and individualization of intracystic bodies.     

Planktonic bloom-forming Cyanobacteria and the eutrophication of lakes and rivers

SUMMARY. 1. Eutrophication of water bodies involves the enrichment of plant nutrients, often followed by significant shifts in the phytoplankton towards Cyanobacteria. When comparing different aquatic systems, even with similar nutrient contents and in the same climatic region, inverse deductions are not valid; i.e. (a) the presence of Cyanobacteria does not necessarily indicate eutrophic conditions, or (b) eutrophic or even poly-trophic conditions do not necessarily support cyanobacterial development.
2. Above a threshold of 10 μg 1⁻¹ total phosphorus, the development of Cyanobacteria can be described by physical factors, such as water column stability. By characterizing different forms of turbulence, the presence or absence of Cyanobacteria in lakes and rivers can be predicted.
3.When the turbulence of the water column is rather low, as it is in sheltered or meromictic lakes, Cyanobacteria can build up dense populations. In nutrient poor systems, species of Oscillatoria and (seldom) Aphanizomenon are dominating.
4.If the turbulence of the water column is high (mixing depth much greater than euphotic depth) or the mixing pattern is irregular, as in slowly flowing or regulated rivers, Cyanobacteria are outcompeted.
5. In the presence of frequent or permanent turbulence, but with mixing depths lower or not much greater than the euphotic zone (as it is the case in shallow, unstratified lakes, mostly eutrophic or even hypertrophic), Cyanobacteria can outgrow normally dominant r -strategists under conditions of low N:P ratios, high water temperatures, pH >9.0 or low light availabilities.
6. If turbulence is comparatively great (10 to $15 m) and stable for a longer period of time, some cyanobacteria are able to adapt.
7. Our statements are discussed on the basis of physiological characteristics.     

World phylogeography and male‐mediated gene flow in the sandbar shark,Carcharhinus plumbeus

The sandbar shark, Carcharhinus plumbeus, is a large, cosmopolitan, coastal species. Females are thought to show philopatry to nursery grounds while males potentially migrate long distances, creating an opportunity for male‐mediated gene flow that may lead to discordance in patterns revealed by mitochondrial DNA (mtDNA) and nuclear markers. While this dynamic has been investigated in elasmobranchs over small spatial scales, it has not been examined at a global level. We examined patterns of historical phylogeography and contemporary gene flow by genotyping 329 individuals from nine locations throughout the species’ range at eight nuclear microsatellite markers and sequencing the complete mtDNA control region. Pairwise comparisons often resulted in fixation indices and divergence estimates of greater magnitude using mtDNA sequence data than microsatellite data. In addition, multiple methods of estimation suggested fewer populations based on microsatellite loci than on mtDNA sequence data. Coalescent analyses suggest divergence and restricted migration among Hawaii, Taiwan, eastern and western Australia using mtDNA sequence data and no divergence and high migration rates, between Taiwan and both Australian sites using microsatellite data. Evidence of secondary contact was detected between several localities and appears to be discreet in time rather than continuous. Collectively, these data suggest complex spatial/temporal relationships between shark populations that may feature pulses of female dispersal and more continuous male‐mediated gene flow.