Diel changes in the benthos of stones and of drift in a southern Australian upland stream

Diel changes in the density of the fauna of stones and of drift were investigated in the Toorongo River, an upland river of southern Australia. The densities of the ten most common taxa and of the total fauna in the drift and on the stones were negatively correlated, with 16 out of 33 cases being significant (p < 0.05). Five of the ten most common taxa displayed a general trend of reaching day-time peaks in the benthos (11 out of 15 cases) and night-time peaks in the drift (10 out of 15 cases). The total density on the stones reached a significant peak in the day-time while the total drift density peaked at night.     

Effects of stone topography on abundance of net-building caddisfly larvae and arthropod diversity in an upland stream

We investigated whether small pits on the surfaces of stream stones affected abundances of net-spinning, hydropsychid larvae (Trichoptera) and species diversity in the Acheron River, southeastern Australia. On stream stones, nets occurred more often in small (at least 5 mm width) pits than expected by chance. However, proportionately high numbers of pits were not associated with high abundances of either of two species of hydropsychid larvae (both Asmicridea spp). A colonization experiment, using bricks with 0, 4, 12 or 30 small (diam. 5.5 mm) and large (13 mm) pits drilled into the top surfaces, showed that numbers of nets were related to numbers of pits. Small pits were preferred over large ones and the pits, as a group, were occupied almost entirely by late instars of both species. However, only Asmicridea sp. 1 was more abundant on pitted bricks; Asmicridea sp. 2 showed no response. The differences between the species, and between the stone and brick results, can be explained by different proportions of late instars in the samples. Many I instars probably did not make nets. Hence, higher numbers of larvae on pitted surfaces is expected only when late instars are relatively frequent, as was true for Asmicridea sp. 1 on bricks. There were no effects of pits per se or increased numbers of hydropsychid nets on species diversity or the abundances of other common species. These results contrast with those of other studies, which found stone topography or hydropsychid nets to increase species diversity on stones.     

Rotifer occurrence in relation to age,depth and trophic state of quarry lakes

An effect of age of quarry lakes on rotifer abundance and species composition has been evaluated. Rotifers occurred in all lakes under study. They were even found in the youngest (2 years of age) one, Rogonica 4, but both rotifer density and species richness were low there. Rotifer communities of much higher density and species diversity were noted in lakes only 4–6 years older. Lakes of over 30 years of age were strongly differentiated in rotifer numbers and species structure. In general, age of quarry lakes has an impact on rotifer communities only at the very beginning of the process of colonization. Several years later other factors become more important, e.g., depth or trophic state of the lakes.     

Immunohistochemistry of carbonic anhydrase in human placenta and fetal membranes

The localization of human carbonic anhydrase (CA) isoenzymes HCA I, HCA II, and rat CA II have been studied in human umbilical cord, chorion laeve including amnion and placenta from first and second trimester and also from term pregnancies. Detection techniques of immunofluorescence and immunoperoxidase were used in cryostat and paraffin sections. Both isoenzymes were found in the villous syncytiotrophoblast throughout pregnancy. HCA I staining patterns in the villous endothelium were highly variable whereas increasing immunoreactivity levels of endothelial HCA II were detected as pregnancy advances. The extravillous cytotrophoblast showed generally weaker levels of immunoreactivity. In amnionic epithelium of membranes, chorionic plate and umbilical cord, higher activities for HCA I, HCA II and rat CA II were found than in all other localizations. Our findings emphasize the importance of enzyme mediated bicarbonate/CO₂ removal from the feto-placental unit as opposed to simple bicarbonate diffusion or carrier mediated transport. As effective transfer routes should be considered not only umbilical cord — placental villi — intervillous space, but also fetal kidney — amnionic fluid — amnion — uterine vessels.     

Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration

In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (F_ST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the ‘migrant pool’ model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species.     

Habitat selection of an expanding beaver (Castor fiber) population in central and upper Morava River basin

Habitat selectivity by European beaver (Castor fiber L., 1758) was studied in 226 km of river channels during their colonization of the Morava River basin (the Czech Republic), which had not been occupied by beavers for hundreds of years. The colonization started after initial reintroductions in 1991 and 1992. Annual increases in colonization of the river system from 1995 to 2007 were 15.5 ± 9.4 SD km year⁻¹ and varied greatly between these years (min 0 km, max 33 km). Beavers appeared to be following a dispersal pattern, in which distant sites are often colonized before close-by sites. The selection of habitat variables during the colonization process varied. In the early phase of colonization, there were many areas with optimal habitat that were not occupied by beavers, and habitat selection appeared chaotic. After this early phase, the most significant habitat variable related to beaver occupation was shown to be the presence of willow (Salix spp.) species. In the later phases, the beaver population expanded into suboptimal habitat. Settlement distance from roads, railways, and urbanized areas became less. When comparing the generalized linear models, a model from the winter of 2003/2004 had the best overall accuracy and showed excellent agreement among observed and fitted values (Cohen’s κ = 0.75). The model suggests that beavers established their home ranges at first in optimal habitat, which had not been occupied before and then subsequently in suboptimal/marginal areas.     

COLONIZATION AND STANDING CROPS OF EPILITHIC ALGAE IN THE SUSQUEHANNA RIVER,PENNSYLVANIA1

A SCUBA diver, using a bar-clamp sampler, collected quantitative epilithic algae samples from artificial substrates (slate and acrylic plates) and river stones at two stations on the Susquehanna River bottom in 1974. At Falls, Pennsylvania, algal colonization on monthly plates (submerged for ca. 30 day periods) was most rapid between September and October. In winter, when algal density on cumulative plates (submerged 2–13 mo) and on stones present in the river peaked at 18,100 and 21,900 units/ mm², respectively, colonization of clean monthly plates nearly ceased. Similar colonization patterns were observed in a portion of the river polluted by coal mine drainages (SSES), but expansion of the algae population at SSES was inhibited by iron in the effluents, and densities never exceeded 2,400 units/mm² on stones or plates. Diatoms composed 95% of the overall standing crop at Falls and 65% at SSES.     

On the reversibility of the B1 2r−B1 2s couple in cobalamins

The cobalt(II)—cobalt(I) interconversion in a number of vitamin B_{1 2} derivatives was investigated by cyclic voltammetry. Particular attention was focused on the factors determining whether the interconversion is reversible. When the lower axial coordination position is occupied by a strong ligand, such as the benzimidazole nucleotide in “base on” cobalamins, the cobalt(II)—cobalt(I) interconversion is irreversible due to a slow reduction of the cobalt(II). However, when the lower axial coordination position is free of a strong ligand, as in most cobinamides or in “base off” cobalamins, the cobalt(II)—cobalt(I) interconversion is nearly perfectly reversible. Possible implications of the observations to B_{1 2}-dependent enzymes are briefly discussed.     

Prevalence of superficial mycoses in the Aosta Valley Region of Italy from 1984 to 1989

Two hundred and thirty soil samples from different localities were examined for the presence of geophilic keratinophilic fungi. Six species namely Microsporum gypseum — 34 isolates, Chrysosporium keratinophilum –29, C. tropicum –20, Keratinophyton terreum –4, Trichophyton terrestre –8 and Chrysosporium species – 3 — were isolated. Most of these fungi were recovered from garden, field and river bank soil. The importance of these findings is briefly discussed.     

The Ladoga seal (Phoca hispida ladogensis Nordq.)

Oligochaetes are the dominant group of macrofauna in a river reach (1–450 m) below the Dobczyce dam on the River Raba. The Oligochaeta made up from 60.2% to 78.7% of the community. The next most abundant group were the Chironomidae comprising 20.5%–38.8% of the fauna. Upstream-downstream movements of the macrofauna were studied at one station, with an oligochaete density of 50 000 ind. m^–2, and a chironomid density about 20 000 ind. m^–2. In the drift the proportions of these two groups were reversed—Chironomidae represented 59% of the drift fauna, and the oligochaetes — about 40%. On the river bottom and in the drift a similar number of species (12–13) of Naididae were identified.In order to compare the intensity of the movement of the various taxonomic groups, the percentage of animals moving upstream and downstream over 24 h was calculated. The highest percentage of the population migrating were dipterans (7.3%). The Chironomidae and Ephemeroptera had similar proportions migrating (3.2% and 2.6% respectively). The Oligochaeta had the lowest value — only 0.6% of animals were displaced in a 24 h period.The Naididae appear to be strongly attached to the substratum and, under normal environmental conditions, their reproduction sufficiently compensated for the decrease in their number associated with the drift or predation.     

Studies on metabolic properties in the Northern Krill, Meganyctiphanes norvegica (Crustacea, Euphausiacea): influence of nutrition and season on pyruvate kinase

The specific activity and the kinetic properties of partly purified pyruvate kinase (PK) (EC 2.7.1.40) from the Northern Krill, Meganyctiphanes norvegica, were investigated in relation to varying food resources. In order to evaluate the effect of starvation on the total energy metabolism, the respiration rates of fed and unfed krill were determined. The FPLC–elution profile of PK displayed two distinct peaks — PK I and II. The first isoform represented 80% of the total PK activity in the organism, and 20% was contributed by the second isoform. PK I was inhibited by ATP but was not influenced by fructose–1,6–bisphosphate (FBP). In contrast, PK II showed ATP inhibition and up to 2.5-fold increased activity by addition of 17 μmol·l⁻¹ FBP. The Michaelis–Menten constants of both isoforms were 2–10-fold higher for ADP than for phosphoenolpyruvate (PEP). Alanine showed no regulatory effect on PK I and II. In specimens starved for 7 days oxygen consumption decreased by 20%. Neither the feeding experiments nor the animals captured in the field during low and high productive seasons indicate that PK properties of M. norvegica are modified in relation to food supply. Accordingly, alternative mechanisms are involved in the depression of the metabolic rate in terms of oxygen consumption.     

Modelling time‐varying low‐temperature‐induced mortality rates for pupae of Tuta absoluta (Gelechiidae,Lepidoptera)

In a series of laboratory experiments, acclimated pupae of Tuta absoluta were exposed to various constant low temperatures in order to estimate their maximum survival times (Kaplan–Meier, Lt_99.99). A Weibull function was fitted to the data points, describing maximum survival time as a function of temperature. In another experiment at ?6°C, the progress of mortality increasing with exposure time was identified. These values were fitted by a sigmoidal function converging asymptotically to 100% mortality for very long exposure times. Analysing mortality data from the maximum survival experiment by a generalized linear model showed a significant common slope parameter (p < .001) that reveals parallelism of the survival curves at each temperature if a log time axis is used. These curves appear stretched (time scaled) if plotted with a nonlogarithmic time axis. By combining these mathematical relations, it was possible to calculate a species‐specific ‘mortality surface’ which exhibits mortalities, depending on temperature and duration of exposure. In order to accumulate hourly mortalities for courses of varying temperatures, an algorithm was developed which yields mortality values from that surface taking into account the attained mortality level. In validation experiments, recorded mortalities were compared against modelled mortalities. Prediction of mortality was partially supported by the model, but pupae experiencing intensely fluctuating temperatures showed decreased mortality, probably caused by rapid cold hardening during exposure. Despite this observation, mortality data converged to distinct levels very close to 100% depending on the intensity of temperature fluctuations that were characteristic for different types of experiments. The highest mortality limit occurred at intensely fluctuating temperatures in laboratory experiments. This constituted a benchmark that was not reached under various field conditions. Thus, it was possible to identify temperature limits for the extinction of field populations of Tuta absoluta pupae.     

An indirect test for a role of the synaptonemal complex in the establishment of sister chromatid cohesiveness

The meiotic behavior of a special maize trisome was quantitatively observed at pachytene, metaphase I, anaphase I, prophase II, metaphase II and anaphase II. The data obtained are consistent with (but do not prove) the model that sister chromatid cohesiveness at anaphase I may be established during pachytene synapsis of the chromosome regions involved. The data suggest, however, that the normal prophase II maintenance of dyad integrity by cohesiveness of sister chromatid centromere regions does not depend upon prior synapsis of these regions, although monads separated from each other on the anaphase I spindle may be delivered to the same prophase II daughter nucleus. — The strands which some of the time connect sister chromatids which are separating equationally at anaphase I show a positive Feulgen staining reaction.     

Elektronenmikroskopische Untersuchungen über die Struktur der Forellenmuskulatur und die Lokalisation der sauren ATPase im Verlaufe der Totenstarre

Zusammenfassung Rückenmuskulatur von Forellen wurde vor Eintritt und während der Totenstarre sowie nach ihrer Lösung (I., II. und III. Abnahme) elektronenmikroskopisch untersucht. Die Forellenmuskulatur zeigt den typischen Aufbau aus dicken und dünnen Myofilamenten. Nach OsO₄-Fixierung sind die I-, A- und H-Bänder in der I. und III. Abnahme schwer abzugrenzen, während sie sich in der II. Abnahme deutlich durch verschiedene Dichte und Filamentanordnung unterscheiden. Der M-Streifen besteht zu jeder Zeit aus Verdickungen der Myofilamente. Der Z-Streifen stellt in der I. und III. Abnahme eine filzartige Verflechtung aus dünnen Filamenten dar. In der II. Abnahme sind jedoch auch im Z-Streifen Filamentverdickungen zu erkennen. Der Innenraum des endoplasmatischen Retikulums und der Cristae mitochondriales wird nach dem Tode zunehmend erweitert. — Die Menge des Bleisulfid-Niederschlages als Äquivalent der sauren ATPase-Aktivität nimmt mit der Zeit nach dem Tode kontinuierlich ab. Die größte Dichte und die geringste Abnahme des Niederschlages weist der M-Streifen auf. Der Z-Streifen zeigt in der I. Abnahme Niederschläge, ist jedoch während der Totenstarre und danach nicht markiert. Der Niederschlag ist streifenförmig in den Grenzbereichen des A-Bandes gegenüber I und H lokalisiert und zeigt in der I. und III. Abnahme eine deutliche Zuordnung zur axialen Periodik. Unter der Totenstarre ist die ATPase-Aktivität nicht so genau lokalisiert. Insbesondere sind die feinen Streifen, die der axialen Periode entsprechen, nicht zu beobachten. — Die ATPase-Lokalisation wird in bezug auf die verschiedenen Kontraktionsmodelle diskutiert.

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Summary The dorsal musculature of the trout before and during rigor mortis as well as during its decrease (stages I, II and III) was examined electron microscopically. The muscles were found to have the typical structure of thin and thick myofilaments. During stages I and III, following OsO₄ fixation, the differentiation between I, A, and H bands was found to be difficult; during stage II, however, they were clearly differentiated by various degrees of density and by the arrangement of the filaments. At any stage the M band appeared to be due to a thickening of the myofilaments. During stages I and III the Z band seemed to be composed of a felt-like network of thin filaments. During stage II, however, the Z band showed also a thickening of the filaments. After death the internal volume of the endoplasmic reticulum and of the cristae mitochondriales becomes increasingly enlarged. — The amount of lead-sulphide precipitate — if taken as the equivalent of the acid ATP-ase activity — decreased constantly with the time after death. The M band showed the highest density and the smallest decrease in the amount of precipitate. During stage I it was possible to demonstrate a precipitate in the Z band; during rigor mortis and afterwards, however, the band was not prominent. The precipitate had a striated appearance and was localized at the zones of transition between A band and I and H bands; a marked relation to the axial periodicity was found during stages I and III. During rigor mortis ATP-ase activity was not as accurately localized. Especially the fine striae, which correspond to the axial periodicity, were not observed. — The localization of ATP-ase is discussed in relation to various models of contraction.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Cellobiohydrolase II is the main conidial-bound cellulase in Trichoderma reesei and other Trichoderma strains

Monoclonal antibodies have been used to determine the presence of cellobiohydrolases I and II (CBH I and II), and endoglucanase I (EG I) on the surface of conidia from Trichoderma reesei QM 9414 and RUT C-30, and 8 other Trichoderma species. For this purpose, proteins were released from the conidial surface by treatment with a non-ionic detergent (Triton X-100 and -octylglucoside), followed by SDS-PAGE/Western blotting and immunostaining. Both CBH I and II were clearly present, but — unlike in extracellular culture fluids from Trichoderma — CBH II was the predominant cellulase. In T. reesei EG I could not be detected. The higher producer strain T. reesei RUT C-30 exhibited a higher conidial level of CBH II than T. reesei QM 9414. In order to assess the importance of the conidial CBH II level for cellulase induction by cellulose, multiple copies of the chb2 gene were introduced into the T. reesei genome by cotransformation using PyrG as a marker. Stable multicopy transformants secreted the 2- to 4-fold level of CBH II into the culture medium when grown on lactose as a carbon source, but their CBH I secretion was unaltered. Upon growth on cellulose, both CBH I and CBH II secretion was enhanced. Those strain showing highest cellulase activity on cellulose also appeared to contain the highest level of conidial bound CBH II. CBH II was also the predominant conidial cellulase in various other Trichoderma sp. However, roughly the same amount of conidial bound CBH II was detected in all strains, although their cellulase production differed considerably.     

Parental care in the rocky intertidal: a case study of adaptation and exaptation in Mediterranean and Atlantic blennies

Summary The main features of the behavioural ecology of rocky intertidal species are compared both within families — though concentrated on blennies — and between habitats. It is suggested that, at the behavioural level, the reduction of vertical and swimming elements in the male sexual and agonistic displays of Blennioidei may constitute an adaptation to typical intertidal conditions, especially in those species that inhabit areas exposed to strong wave action. The other aspect which is discussed is the prevalence of parental care in rocky intertidal fishes. In these fishes parental care is much more frequent than for marine fishes as a whole. Taken alone, this could also suggest that guarding evolved as an adaptation during the process of colonization of these habitats. The hypothesis proposed in this paper is that guarding was already present in the ancestors of the resident species, at least in the majority of cases. Many differences in interhabitat studies may express the action of the environment, not as an agent of natural selection, but as a filter, which prevented some groups from invading a given habitat and, at the same time, made colonization easier for other groups. When a number of taxa that colonized a given habitat display clear similarities in their behaviour and their biology, adaptation is not necessarily demonstrated. There is evidence in the literature to support the hypothesis that those traits were already present in the ancestors of the rocky intertidal resident fishes, thus being best viewed as exaptations.     

Development in an estuarine fouling community: The influence of early colonists on later arrivals

Summary Experiments were performed to determine if earlier colonists inhibited, enhanced, or were necessary for establishment of later colonists during development of an estuarine fouling community at Lewes, Delaware. We determined the significance of earlier stages on the successional process by functionally removing early colonizing species. Since settlement of sessile invertebrates onto our experimental test plates was seasonal, we were able to accomplish functional removal of early colonists by putting out clean test panels after these species had ceased settling. Comparisons between panels initially submerged at three different times in 1974 and 1975, and between panels put out at one-month intervals throughout the study (to describe seasonal settlement patterns) allowed us to determine interactions between adult populations of earlier colonists and colonizing individuals of later arriving species.The dominant sessile species in our system and their times of settlement were: a barnacle (Balanus improvisus) — April through June, a polychaete (Hydroides dianthus) — July and August, a tunicate (Molgula manhatensis) — June through October, a hydroid (Tubularia crocea) — July through October, and a mussel (Mytilus edulis) — November through April. All successional series eventually came to be dominated by M. edulis, and it persisted as the dominant for over a year.A variety of species interactions were observed. M. edulis inhibited colonization by all other dominants and B. improvisus partially inhibited settlement of M. manhattensis. The presence of adult M. manhattensis had no influence on summer settlement of T. crocea, but the hydroids enhanced settlement of tunicates in the fall. During both years of our study, larger settlements of mussels were noted on panels harboring tunicates and hydroids than on bare surfaces. H. dianthus, on the other hand, became established only on bare substrates, and colonization was almost totally inhibited by other dominants.Development in our fouling community did not conform to any single model of community development presented to date. Instead, components of several models were observed within our relatively simple (in terms of number of species) system. For example, facilitation (enhancement of later colonists by earlier ones) and inhibition (resistance of earlier colonists to invasion by later colonists) were both observed. However, we found no evidence earlier colonists were essential for establishment of the next developmental stage. In fact, inhibitory interactions appeared to be much more prevalent than facilitative interactions. The former may also have more profound effects on community development since they more often determine eventual species compositions.     

Endozoochory of a dry‐fruited tree aids quarry passive restoration and seed soaking further increases seedling emergence

As practitioners promote passive restoration as a complementary approach to technical reclamation, it is imperative to know its drivers. Although the consequences of endozoochory can be crucial to passive restoration success, few experimental studies assess the use of heavily disturbed sites by seed dispersers such as carnivores and how the seeds they bring in emerge and survive. Using an indoor sowing experiment conducted in a quarry located within a natural park in Portugal, we examined for the first time how carnivore endozoochorous seeds collected in the quarry potentially influence its passive restoration, through effects on plant emergence and survival. Also, we tested whether sowing date and water soaking, relevant factors when sowings are to be carried out, would affect seedling emergence and mortality rates when compared with the effect of endozoochory. Our target species were included in the revegetation plan of the quarry, of which endozoochorous seeds of Carob tree (Ceratonia siliqua) were collected in sufficient number for analysis. Irrespective of the carnivore species, endozoochorous carob seeds performed similarly to untreated seeds regarding emergence rates. Endozoochorous carob seedlings showed greater mortality rates but the net result for the plant can still be the colonization of recently vacant habitats by a large proportion of viable seeds. Concerning sowing date, the later carob seeds were sown over the fruit‐ripening season the faster seedlings emerged. Water soaking increased emergence rate by 6.5 times. Broadly, sowings with previous soaking and carnivore‐mediated seed dispersal of this dry‐fruited tree can jointly enhance quarry restoration.     

Univalent behaviour at anaphase I in desynaptic rye

The Anaphase-I behaviour of univalents produced by desynapsis has been studied in four inbred lines of rye. — The analyses show that the distribution of numbers of equationally dividing univalents per cell at anaphase-I does not conform to the statistical expectation of randomness. The pattern of this distribution leads us to the assumption that two types of univalent pairs are present at metaphase I: in type I both members of the pair can divide equationally or reductionally, independent of one another. In type II both members of the pair always divide reductionally. Under this assumption a theoretical model was made which fits the observed distribution of the number of equationally dividing univalents per cell. — It is suggested that the difference of anaphase-I behaviour between these two types of univalent pairs is determined by the moment of metaphase I at which they are formed.