Effects of density-dependence and weather on population changes of English passerines using a non-experimental paradigm

The Common Birds Census documents changes in the populations of the more abundant British land birds. Here we analyse the CBC data for various English passerines to discover the separate effects of weather and of density-dependent feedback on their annual population changes. Density dependence is generally apparent in the data from woodland plots, less so in those from farmland. There are clear effects of weather, particularly in farmland. Prolonged snowfall in winter reduces populations of most species; frost and low temperatures appear much less important. Rainfall in March and April increases numbers censused in the spring but this may be an artefact. We discuss ways in which analyses such as these should be taken forward.
We consider whether this work is respectable science, arguing that monitoring through the CBC goes much further than mere surveillance of numbers, that such monitoring is important in wildlife management, and that density dependence is not a bankrupt paradigm. Long-term data gathering is an essential part of ecological science, even in programmes not designed at the outset to test specific hypotheses.     

Enhancing pest control in annual crops by conservation of predatory Heteroptera

Conservation biological control (CBC) combines a diverse set of actions aiming to enhance pest regulation by the provision of pest natural enemies’ preservation in the crop environment. This is accomplished through appropriate implementation practices and the creation of infrastructures of non-crop vegetation. On most annual crops, omnivorous heteropteran predators comprise the main assemblage of native natural enemies. Their populations, when protected from pesticides, have shown a high potential in biological control. Aiming to promote their functioning in CBC, efforts targeted to modify the crop environment are focusing on the determination of their non-crop host plants that can support the predators’ persistence as well as the emigration of these predators to the nearby crops. Nonetheless, relatively few studies seek to collect essential and adequately verified data for the practical implementation of CBC approaches. In this review, the advances already developed are illustrated, the shortcomings are discussed and the future research needs are highlighted in an effort to intensify efforts for CBC developments on annual crops.     

Temporal changes in the migration phenology of turtle doves Streptopelia turtur in Britain, based on sightings from coastal bird observatories

Using daily counts of birds seen at six coastal bird observatories in southern and eastern England, we explored the migration phenology of turtle doves during the period 1963 to 2000. Annual totals increased threefold up to the late 1970s then decreased again, in accordance with the BTO Common Birds Census (CBC) index of abundance. Median annual spring arrival and autumn departure dates of turtle doves were not related to abundance (CBC index) or mean temperature in spring or summer respectively. Although median annual spring arrival date has not altered over the 38-year period, median annual autumn departure date has become earlier by 8 days. This has resulted in a shortening of the breeding season by 12 days, which ties in with a reduction in average number of nesting attempts per pair observed by a recent autecological study. It is possible that breeding turtle doves are now out of phase with peaks in food availability. This may have resulted in reduced breeding performance and earlier termination of the breeding season, and may have partly contributed to the decline of the species.     

Structured and unstructured citizen science: Seven decades of expanding bird populations in central Ontario,Canada

Citizens’ observations of wildlife offer a wealth of information. Such data, however, may be prone to biases or inaccuracies — in particular, the over-reporting of novel species and under-reporting of common or mundane species. Few studies have assessed the relationship between unstructured and structured observations using long-term data. We compared 69 years of voluntary bird sightings, recorded in the regular publication of Peterborough Field Naturalists (PFN), 1948–2016, to systematic Christmas Bird Counts (CBC; during winter) and Breeding Bird Surveys (BBS; during spring) in central Ontario, Canada. We focused on seven species that had expanded their ranges into the area: Northern Cardinal (Cardinalis cardinalis), House Finch (Haemorhous mexicanus), Purple Finch (Haemorhous purpureus), Red-bellied Woodpecker (Melanerpes carolinus), Wild Turkey (Meleagris gallopavo), Canada Goose (Branta canadensis), and American Robin (Turdus migratorius). For each species, we compared the first record, the annual number of sightings, and the annual relative abundance from the PFN to the first record and annual relative abundance in the CBC and BBS. We anticipated that naturalists’ accounts would be more sensitive to the arrival of novel species but would underestimate abundance as the species became common.In general, our results agreed with these predictions. In 11 of 12 cases, the naturalists detected a species well in advance of the CBC and BBS — on average by 1½ decades (range: 5–33 years). The correlations in bird abundance between unstructured (PFN) and structured (CBC and BBS) data were variable; most were weak and negative. We found significant negative correlations for the two most common species, Northern Cardinal (winter) and House Finch (spring), as well as for Wild Turkey (winter), and a positive correlation for the rarest species, the Red-bellied Woodpecker (spring). We surmise that novelty underlies these results — that rarity increases the likelihood of reporting by non-professionals. We conclude that unstructured observations are valuable in detecting novel species, but they may be inconsistent, even inverse, indicators of the abundance of expanding species, once established.     

The effect of cannabichromene on adult neural stem/progenitor cells

Apart from the psychotropic compound Δ⁹-tetrahydrocannabinol (THC), evidence suggests that other non-psychotropic phytocannabinoids are also of potential clinical use. This study aimed at elucidating the effect of major non-THC phytocannabinoids on the fate of adult neural stem progenitor cells (NSPCs), which are an essential component of brain function in health as well as in pathology. We tested three compounds: cannabidiol, cannabigerol, and cannabichromene (CBC), and found that CBC has a positive effect on the viability of mouse NSPCs during differentiation in vitro. The expression of NSPC and astrocyte markers nestin and Glial fibrillary acidic protein (GFAP), respectively, was up- and down-regulated, respectively. CBC stimulated ERK1/2 phosphorylation; however, this effect had a slower onset in comparison to typical MAPK stimulation. A MEK inhibitor, U0126, antagonized the up-regulation of nestin but not the down-regulation of GFAP. Based on a previous report, we studied the potential involvement of the adenosine A1 receptor in the effect of CBC on these cells and found that the selective adenosine A1 receptor antagonist, DPCPX, counteracted both ERK1/2 phosphorylation and up-regulation of nestin by CBC, indicating that also adenosine is involved in these effects of CBC, but possibly not in CBC inhibitory effect on GFAP expression. Next, we measured ATP levels as an equilibrium marker of adenosine and found higher ATP levels during differentiation of NSPCs in the presence of CBC. Taken together, our results suggest that CBC raises the viability of NSPCs while inhibiting their differentiation into astroglia, possibly through up-regulation of ATP and adenosine signalling.     

Survival of the recombinant Bacteroides thetaiotaomicron strain BTX in in vitro rumen incubations

The survival of Bacteroides thetaiotaomicron strain BTX under rumen-simulating conditions was studied. Strain BTX is a recombinant variant of strain 5482 engineered for the production of high levels of xylanase, an enzyme important in the degradation of hemicellulose. Strain BTX was not inhibited by compounds present in rumen fluid and it grew well in media containing rumen fluid (up to 75%) or high concentrations of volatile fatty acids (total concentration, 100 mmol l⁻¹). The ability of strain BTX to compete with other micro-organisms under rumen-like conditions was studied in in vitro incubations of rumen contents. These experiments employed a consecutive batch culture (CBC) system consisting of alfalfa suspended in a rumen fluid buffer inoculated with blended rumen contents and maintained by transfers (10%, v/v) at 48 h intervals. CBC cultures contained a diversity of microbial morphotypes and accumulated fermentation products in rumen-like proportions. When added alone, the numbers of BTX cells were maintained for only a few hours, and then declined precipitously until undetectable after 48 h. If CBC cultures were also supplemented with chondroitin sulphate (a mucopolysaccharide used by Bact. thetaiotaomicron ), strain BTX grew and the pattern of its population generally followed that of the total population of ruminal bacteria in these cultures. When transferred into fresh CBC cultures containing chondroitin sulphate, BTX was again able to grow and increase in numbers, but to a diminished degree. Although BTX was able to survive and maintain itself in chondroitin sulphate supplemented cultures, this was at a very low level (10¹⁰ ml⁻¹). The potential for manipulation of rumen function by inoculation with recombinant bacteria is discussed.     

Prior Adjuvant Tamoxifen Treatment in Breast Cancer Is Linked to Increased AIB1 and HER2 Expression in Metachronous Contralateral Breast Cancer

Aim

The estrogen receptor coactivator Amplified in Breast Cancer 1 (AIB1) has been associated with an improved response to adjuvant tamoxifen in breast cancer, but also with endocrine treatment resistance. We hereby use metachronous contralateral breast cancer (CBC) developed despite prior adjuvant tamoxifen for the first tumor as an “in vivo”-model for tamoxifen resistance. AIB1-expression in the presumable resistant (CBC after prior tamoxifen) and naïve setting (CBC without prior tamoxifen) is compared and correlated to prognosis after CBC.

Methods

From a well-defined population-based cohort of CBC-patients we have constructed a unique tissue-microarray including >700 patients.

Results

CBC developed after adjuvant tamoxifen more often had a HER2-positive/triple negative-subtype and a high AIB1-expression (37% vs. 23%, p = 0.009), than if no prior endocrine treatment had been administered. In patients with an estrogen receptor (ER) positive CBC, a high AIB1-expression correlated to an inferior prognosis. However, these patients seemed to respond to tamoxifen, but only if endocrine therapy had not been administered for BC1.

Conclusions

Metachronous CBC developed after prior endocrine treatment has a decreased ER-expression and an increased HER2-expression. This is consistent with endocrine treatment escape mechanisms previously suggested, and indicates metachronous CBC to be a putative model for studies of treatment resistance “in vivo”. The increased AIB1-expression in CBC developed after prior tamoxifen suggests a role of AIB1 in endocrine treatment resistance. In addition, we found indications that the response to tamoxifen in CBC with a high AIB1-expression seem to differ depending on previous exposure to this drug. A different function for AIB1 in the tamoxifen treatment naïve vs. resistant setting is suggested, and may explain previously conflicting results where a high AIB1-expression has been correlated to both a good response to adjuvant tamoxifen and tamoxifen resistance.     

Avian nest predation, competition and the decline of British Marsh Tits Parus palustris

Data from long-term schemes monitoring abundance and breeding performance were used to investigate the patterns and causes of decline of the Marsh Tit Parus palustris in Britain. Data from the British Trust for Ornithology's Common Birds Census (CBC) showed that declines have occurred to a similar extent in both woodland and farmland. Novel analyses of CBC data with respect to the corresponding data on the abundance of potential avian nest predators and competitors provided no evidence that increases in the numbers of either group have had a deleterious effect on the species. There were no significant relationships with predator numbers and all significant relationships with potential competitors were positive, suggesting common responses to environmental conditions rather than any negative effects of increases in competitor populations. Further evidence for a lack of any effect of nest predation comes from the absence of any decline in breeding success and, specifically, in nest failure rates, over time: failure rates actually fell during the period of decline. The most likely cause of the decline is the degradation of woodland habitats, and the specific ways in which this may have affected Marsh Tits (as opposed to congeneric species whose populations are healthier) are discussed.     

Distinguishing species

Given two organisms, how can one distinguish whether they belong to the same species or not? This might be straightforward for two divergent organisms, but can be extremely difficult and laborious for closely related ones. A molecular marker giving a clear distinction would therefore be of immense benefit. The internal transcribed spacer 2 (ITS2) has been widely used for low-level phylogenetic analyses. Case studies revealed that a compensatory base change (CBC) in the helix II or helix III ITS2 secondary structure between two organisms correlated with sexual incompatibility. We analyzed more than 1300 closely related species to test whether this correlation is generally applicable. In 93%, where a CBC was found between organisms classified within the same genus, they belong to different species. Thus, a CBC in an ITS2 sequence-structure alignment is a sufficient condition to distinguish even closely related species.     

Cdc42 stimulates RNA splicing via the S6 kinase and a novel S6 kinase target, the nuclear cap-binding complex

Cdc42 is a low molecular weight GTP-binding protein that plays a key regulatory role in a variety of cellular activities. The importance of the coordination of different cell functions by Cdc42 is underscored by the fact that a constitutively active Cdc42 mutant induces cellular transformation. In this study, we describe a novel function for Cdc42: its ability to stimulate pre-messenger RNA splicing. This activity is dependent on cysteine 37 in the effector loop of Cdc42 but is not dependent on cell growth. A likely candidate protein for mediating the Cdc42 effects on pre-mRNA splicing is the nuclear RNA cap-binding complex (CBC), which plays a key role in an early step of cap-dependent RNA splicing. Activation of the CBC by Cdc42 can be inhibited by rapamycin. Additionally, phosphatidylinositol 3-kinase and the Cdc42 effector, pp70 S6 kinase, stimulate the RNA cap-binding activity of the CBC. S6 kinase may directly target the CBC in vivo as it can phosphorylate the 80-kDa subunit of the CBC, CBP80, at residues that are subject to a growth factor-dependent and rapamycin-sensitive phosphorylation in vivo. Together these data suggest the involvement of a Cdc42-S6 kinase pathway in the regulation of RNA splicing, mediated by an increase in capped RNA binding by the CBC, as well as raise the possibility that the effects of Cdc42 on cell growth may be due in part to its regulation of RNA processing.     

Resistance of Pseudomonas to Quaternary Ammonium Compounds. I. Growth in Benzalkonium Chloride Solution

Resistant cells of Pseudomonas aeruginosa and a waterborne Pseudomonas sp. (strain Z-R) were able to multiply in nitrogen-free minimal salts solution containing various concentrations of commercially prepared, ammonium acetate-buffered benzalkonium chloride (CBC), a potent antimicrobial agent. As the CBC concentration increased, growth increased until a point was reached at which the extent of growth leveled off or was completely depressed. Minimal salts solutions of pure benzalkonium chloride (PBC) containing no ammonium acetate did not support bacterial growth. When ammonium acetate was added to PBC solutions in the same concentrations found in CBC solutions, growth patterns developed that were comparable to those found with CBC. Likewise, (NH(4))(2)SO(4) added to PBC solutions supported growth of both organisms. P. aeruginosa was initially resistant to CBC levels of 0.02% and it was adapted to tolerate levels as high as 0.36%. Strain Z-R was naturally resistant to 0.4% CBC. Since ammonium acetate, carried over by the CBC used in drug formulations and disinfectant solutions, has the potential to support the growth of resistant bacteria and thus make possible the risk of serious infection, it is suggested that regulations allowing the presence of ammonium acetate in CBC solution be reconsidered.     

Pappus part number in annual species ofMicroseris (Compositae,Cichoriaceae)

All North American annual species of the genusMicroseris have a five-part pappus, the one South American annual,M. pygmaea, has ten pappus parts. The pappus develops over a constant number of ten provascular bundles with or without inhibition between alternate sites of pappus development. Each natural population contains a predictable proportion of achenes with aberrant pappus part numbers. Hybridization betweenM. bigelovii (5 parts) andM. pygmaea results in F 1 and F 2 plants with many aberrant achenes. In each plant either five or ten can be shown to be the basic number with aberrant numbers following a Poisson distribution for numbers added to 5 or deleted from 10. Occasional plants show no basic number but have a random distribution of numbers about an intermediate mean. The evolutionary genetics of this character is discussed.     

Prospects for the Management of Invasive Alien Weeds Using Co-Evolved Fungal Pathogens: A Latin American Perspective

Invasive alien weeds pose a serious threat to the biodiversity of natural ecosystems and a significant constraint to agricultural production worldwide. The use of co-evolved natural enemies, a strategy referred to as classical biological control (CBC), has proven to be a potentially efficacious, cost-effective, and safe option for the management of alien weeds. An analysis of CBC of invasive weeds in Latin America is presented, which shows that only 5% of the worldwide releases of agents, overwhelmingly arthropod, have been in this region. Fungal pathogens are increasingly being considered in CBC programmes, and there are now 11 examples of Latin American fungi having been released as biocontrol agents in other regions of the world. In contrast, only three weed pathogens have been deliberately released in the region. Possible reasons for the paucity of CBC programmes in Latin America are presented, despite the presence of a significant number of alien weed species (60 are listed). An analysis of these weeds reveals that many of them could be amenable to control using natural enemies, including nine weed species for which CBC programmes have been successfully implemented elsewhere in the world. In addition, for many of these 60 species, a co-evolved and damaging mycobiota has already been recorded. The prospects for management of invasive alien weeds in Latin America, using co-evolved fungal pathogens, are assessed with particular reference to selected species from the genera Ambrosia, Broussonetia, Calotropis, Commelina, Cyperus, Dichrostachys, Echinochloa, Pittosporum, Rottboellia, Rubus, Sonchus and Ulex. This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of a fluorescent cobalamin analogue for analysis of the binding kinetics. A study employing recombinant human transcobalamin and intrinsic factor

Fluorescent probe rhodamine was appended to 5' OH-ribose of cobalamin (Cbl). The prepared conjugate, CBC, bound to the transporting proteins, intrinsic factor (IF) and transcobalamin (TC), responsible for the uptake of Cbl in an organism. Pronounced increase in fluorescence upon CBC attachment facilitated detailed kinetic analysis of Cbl binding. We found that TC had the same affinity for CBC and Cbl (K(d) = 5 x 10(-15) m), whereas interaction of CBC with the highly specific protein IF was more complex. For instance, CBC behaved normally in the partial reactions CBC + IF(30) and CBC + IF(20) when binding to the isolated IF fragments (domains). The ligand could also assemble them into a stable complex IF(30)-CBC-IF(20) with higher fluorescent signal. However, dissociation of IF(30)-CBC-IF(20) and IF-CBC was accelerated by factors of 3 and 20, respectively, when compared to the corresponding Cbl complexes. We suggest that the correct domain-domain interactions are the most important factor during recognition and fixation of the ligands by IF. Dissociation of IF-CBC was biphasic, and existence of multiple protein-analogue complexes with normal and partially corrupted structure may explain this behaviour. The most stable component had K(d) = 1.5 x 10(-13) m, which guarantees the binding of CBC to IF under physiological conditions. The specific intestinal receptor cubilin bound both IF-CBC and IF-Cbl with equal affinity. In conclusion, the fluorescent analogue CBC can be used as a reporting agent in the kinetic studies, moreover, it seems to be applicable for imaging purposes in vivo.     

Novel and essential subunits in the 300-kilodalton nuclear cap binding complex of Trypanosoma brucei

One of the unique aspects of RNA processing in trypanosomatid protozoa is the presence of a cap 4 structure (m7Gpppm2(6)AmpAmpCmpm3Um) at the 5' end of all mRNAs. The cap 4 becomes part of the mRNA through trans-splicing of a 39-nucleotide-long sequence donated by the spliced leader RNA. Although the cap 4 modifications are required for trans-splicing to occur, the underlying mechanism remains to be determined. We now describe an unconventional nuclear cap binding complex (CBC) in Trypanosoma brucei with an apparent molecular mass of 300 kDa and consisting of five protein components: the known CBC subunits CBP20 and importin-alpha and three novel proteins that are only present in organisms featuring a cap 4 structure and trans-splicing. Competitive binding studies are consistent with a specific interaction between the CBC and the cap 4 structure. Downregulation of several individual components of the T. brucei CBC by RNA interference demonstrated an essential function at an early step in trans-splicing. Thus, our studies are consistent with the CBC providing a mechanistic link between cap 4 modifications and trans-splicing.