Pollen selection — past,present and future

 A series of studies, recently reviewed, has established that approximately 60% of the structural genes which are expressed in the sporophytic portion of the angiosperm life cycle are also expressed and exposed to selection in the pollen. Given the haploidy and large population sizes of pollen grains, a substantial portion of the sporophytic genome could thus be periodically exposed to a bacterial type of mass screening. This extraordinary possibility is often subject to some skepticism which may, of course, be justified. However, recent attempts to apply models appear to be inappropriate in this context, in part because these attempts overlook an important source of genetic variation, and also because they assume fixed values for selection and fitness. More recently, studies of pollen/pollen interactions have suggested that what Linskens termed the ”programic phase” may represent an arena for important, and largely unexplored phenomena, some of which are discussed here. Received: 3 June 1996 / Revision accepted: 26 July 1996     

The β-lactam antibiotics: past, present, and future

The discovery and development of the -lactam antibiotics are among the most powerful and successful achievements of modern science and technology. Since Fleming's accidental discovery of the penicillin-producing mold, seventy years of steady progress has followed, and today the -lactam group of compounds are the most successful example of natural product application and chemotherapy. Following on the heels of penicillin production by Penicillium chrysogenum came the discoveries of cephalosporin formation by Cephalosporium acremonium, cephamycin, clavam and carbapenem production by actinomycetes, and monocyclic -lactam production by actinomycetes and unicellular bacteria. Each one of these groups has yielded medically-useful products and has contributed to the reduction of pain and suffering of people throughout the world. Research on the microbiology, biochemistry, genetics and chemistry of these compounds have continued up to the present with major contributions being made by both individual and collaborative groups from industry and academia. The discovery of penicillin not only led to the era of the wonder drugs but provided the most important antibiotics available to medicine. Continued efforts have resulted in the improvement of these compounds with respect to potency, breadth of spectrum, activity against resistant pathogens, stability and pharmacokinetic properties. On the research front, major advances are being made on structural and regulatory biosynthetic genes and metabolic engineering of the pathways involved. New semisynthetic compounds especially those designed to combat resistance development are being examined in the clinic, and unusual non-antibiotic activities of these compounds are being pursued. Although seventy years of age, the -lactams are not yet ready for retirement.     

Fishery of Lake Ladoga — past, present and future

The post-war fishery of Lake Ladoga can be divided according to its catch level into four periods. In the years 1945–1954 the total annual catch increased, and reached the level of 4000 tonnes. In this period the fish stocks that had increased during the war years were intensively exploited. However, this fishery was not in balance with the stocks during the period 1955–1963. As a consequence, the catch decreased drastically, being sometimes less than 2000 tonnes.Controlling the fishery restored the abundance of whitefish Coregonus lavaretus (L.) and zander Stizostedion lucioperca (L.). This increased the total annual catch to about 5500 tonnes in 1964–1989. However, the fishery control measures have not been sufficient to achieve the conservation of salmon Salmo solar L. m. sebago, brown trout Salmo trutta L. and the migratory lake whitefish stocks.A decrease in the total fish catch has been observed since 1990. This decrease may be related to the deterioration of the environment of Lake Ladoga, caused by anthropogenic factors. The unfavourable state of the ecosystem has led to decline of the whitefish stocks and, especially during the last few years, to drastical decline of zander.Acute problems, to be faced in the near future, are connected with the hatchery maintenance of several river-spawning stocks, e.g. salmon, brown trout and migratory whitefish, because the existing fish hatcheries are insufficient in capacity and technically outdated.     

The prokaryotic tree of life: past, present... and future?

No accepted phylogenetic scheme for prokaryotes emerged until the late 1970s. Prior to that, it was assumed that there was a phylogenetic tree uniting all prokaryotes, but no suitable data were available for its construction. For 20 years, through the 1980s and 1990s, rRNA phylogenies were the gold standard. However, beginning in the last decade, findings from genomic data have challenged this new consensus. Gene trees can conflict greatly, and strains of the same species can differ enormously in genome content. Horizontal gene transfer is now known to be a significant influence on genome evolution. The next decade is likely to resolve whether or not we retain the centuries-old metaphor of the tree for all of life.     

The Paradigms They Are a-Changin’: past,present and future of PVC bacteria research

These are exciting times for PVC researchers! The PVC superphylum is composed of the bacterial phyla Planctomycetes, Verrucomicrobia, Chlamydiae (those three founders giving it its name), Lentisphaerae and Kirimatiellaeota as well as some uncultured candidate phyla, such as the Candidatus Omnitrophica (previously known as OP3). Despite early debates, most of the disagreements that surround this group of bacteria have been recently resolved. In this article, we review the history of the study of PVC bacteria, with a particular focus on the misinterpretations that emerged early in the field and their resolution. We begin with a historical perspective that describes the relevant facts of PVC research from the early times when they were not yet termed PVC. Those were controversial times and we refer to them as the “discovery age” of the field. We continue by describing new discoveries due to novel techniques and data that combined with the reinterpretations of old ones have contributed to solve most of the discordances and we refer to these times as the “illumination age” of PVC research. We follow by arguing that we are just entering the “golden age” of PVC research and that the future of this growing community is looking bright. We finish by suggesting a few of the directions that PVC researches might take in the future.     

Ecological research in the tropical alpine ecosystems of the Venezuelan páramo: past,present and future

ABSTRACT

Background: Tropical mountain ecosystems of the Northern Andes have long fascinated researchers because of the unique conditions associated with cold climates in equatorial latitudes. More than six decades have elapsed since the beginning of systematic ecological research in the Venezuelan páramos, making them one of the best-studied tropical alpine regions in the world.

Aims: We review the conceptual development and state of the art of ecological research in the Venezuelan páramos, with emphasis on environmental and plant ecology research, presenting a general framework for the studies included in this special issue.

Methods: We provide a historical sketch of the periods that have marked ecological studies in the Venezuelan páramos. Then, we synthesise research on environmental drivers, plant population and community ecology, ecosystem functioning, the response of the páramo to climate change and human disturbance; we finally consider agroecology and conservation.

Results and conclusions: This review demonstrates the significant contributions made to alpine ecology in key areas such as biodiversity/ecosystem function changes during succession, nutrient cycling, species interactions and socio-ecological research. We indicate the need to develop a more integrated view of the links between evolutionary processes, functional diversity, community dynamics and ecosystem services both in natural and human-impacted areas.     

The dosimetry system DS86 and the neutron discrepancy in Hiroshima – historical review, present status, and future options

The historical development of the dosimetry systems for Hiroshima and Nagasaki is outlined from the time immediately after the A-bomb explosions to the publication of the dosimetry system DS86 in 1987, and the present status of the so-called Hiroshima neutron discrepancy is summarized. Several long-lived radionuclides are discussed with regard to their production by neutrons from the A-bomb explosions. With the exception of ⁶³Ni, these radionuclides have not, up to now, been measured in samples from Hiroshima and Nagasaki. Two of them, ⁶³Ni in copper samples and ³⁹Ar in granite samples, were predominantly produced by fast neutrons. ⁶³Ni can be determined by accelerator mass spectrometry with a gas-filled analyzing magnet. It should be measurable, in the near future, in copper samples up to 1500 m from the hypocenter in Hiroshima. ³⁹Ar can be measured in terms of low-level beta-counting. This should be feasible up to a distance of about 1000 m from the hypocenter. Three radionuclides, ¹⁰Be, ¹⁴C , and ⁵⁹Ni, were produced predominantly by thermal neutrons with smaller fractions due to the epithermal and fast neutrons, which contribute increasingly more at larger distances from the hypocenter. State-of-the-art accelerator mass spectrometry is likely to permit the determination of ¹⁰Be close to the hypocenter and of ¹⁴C up to a distance of about 1000 m. ⁵⁹Ni should be detectable up to a distance of about 1000 m in terms of accelerator mass spectrometry with a gas-filled magnet. The measurements of ¹⁰Be, ¹⁴C, ³⁹Ar, ⁵⁹Ni – and potentially of ¹³¹Xe – can be performed in the same granitic sample that was already analyzed for ³⁶Cl, ⁴¹Ca, ⁶⁰Co, ¹⁵²Eu, and ¹⁵⁴Eu. This will provide extensive information on the neutron spectrum at the specified location, and similarly complete analyses can conceivably be performed on granite samples at other locations. Received: 7 May 1998 / Accepted in revised form: 16 September 1998     

Bacterial genomes in epidemiology—present and future

Sequence data are well established in the reconstruction of the phylogenetic and demographic scenarios that have given rise to outbreaks of viral pathogens. The application of similar methods to bacteria has been hindered in the main by the lack of high-resolution nucleotide sequence data from quality samples. Developing and already available genomic methods have greatly increased the amount of data that can be used to characterize an isolate and its relationship to others. However, differences in sequencing platforms and data analysis mean that these enhanced data come with a cost in terms of portability: results from one laboratory may not be directly comparable with those from another. Moreover, genomic data for many bacteria bear the mark of a history including extensive recombination, which has the potential to greatly confound phylogenetic and coalescent analyses. Here, we discuss the exacting requirements of genomic epidemiology, and means by which the distorting signal of recombination can be minimized to permit the leverage of growing datasets of genomic data from bacterial pathogens.     

How past and present influence the foraging of clonal plants?

Clonal plants spreading horizontally and forming a network structure of ramets exhibit complex growth patterns to maximize resource uptake from the environment. They respond to spatial heterogeneity by changing their internode length or branching frequency. Ramets definitively root in the soil but stay interconnected for a varying period of time thus allowing an exchange of spatial and temporal information. We quantified the foraging response of clonal plants depending on the local soil quality sampled by the rooting ramet (i.e. the present information) and the resource variability sampled by the older ramets (i.e. the past information). We demonstrated that two related species, Potentilla reptans and P. anserina, responded similarly to the local quality of their environment by decreasing their internode length in response to nutrient-rich soil. Only P. reptans responded to resource variability by decreasing its internode length. In both species, the experience acquired by older ramets influenced the plastic response of new rooted ramets: the internode length between ramets depended not only on the soil quality locally sampled but also on the soil quality previously sampled by older ramets. We quantified the effect of the information perceived at different time and space on the foraging behavior of clonal plants by showing a non-linear response of the ramet rooting in the soil of a given quality. These data suggest that the decision to grow a stolon or to root a ramet at a given distance from the older ramet results from the integration of the past and present information about the richness and the variability of the environment.     

Too hot to die? The effects of vegetation shading on past,present, and future activity budgets of two diurnal skinks from arid Australia

Behavioral thermoregulation is an important mechanism allowing ectotherms to respond to thermal variations. Its efficiency might become imperative for securing activity budgets under future climate change. For diurnal lizards, thermal microhabitat variability appears to be of high importance, especially in hot deserts where vegetation is highly scattered and sensitive to climatic fluctuations. We investigated the effects of a shading gradient from vegetation on body temperatures and activity timing for two diurnal, terrestrial desert lizards, Ctenotus regius, and Morethia boulengeri, and analyzed their changes under past, present, and future climatic conditions. Both species’ body temperatures and activity timing strongly depended on the shading gradient provided by vegetation heterogeneity. At high temperatures, shaded locations provided cooling temperatures and increased diurnal activity. Conversely, bushes also buffered cold temperature by saving heat. According to future climate change scenarios, cooler microhabitats might become beneficial to warm‐adapted species, such as C. regius, by increasing the duration of daily activity. Contrarily, warmer microhabitats might become unsuitable for less warm‐adapted species such as M. boulengeri for which midsummers might result in a complete restriction of activity irrespective of vegetation. However, total annual activity would still increase provided that individuals would be able to shift their seasonal timing towards spring and autumn. Overall, we highlight the critical importance of thermoregulatory behavior to buffer temperatures and its dependence on vegetation heterogeneity. Whereas studies often neglect ecological processes when anticipating species’ responses to future climate change the strongest impact of a changing climate on terrestrial ectotherms in hot deserts is likely to be the loss of shaded microhabitats rather than the rise in temperature itself. We argue that conservation strategies aiming at addressing future climate changes should focus more on the cascading effects of vegetation rather than on shifts of species distributions predicted solely by climatic envelopes.     

Monovalent protein-degraders – Insights and future perspectives

The therapeutic potential of interfering with dysregulated proteins by inducing its selective degradation has been pursued using different mechanisms. In the present article, we review representative examples of monovalent protein-degraders that, contrary to the proteolysis targeting chimeras, achieve target degradation without displaying recognition motifs for the recruitment of E3 ubiquitin ligases. We also highlight new technologies and assays that may brought to bear on the discovery of common elements that could predict and enable the selective degradation of pathogenic targets by monovalent protein-degraders. The successful application of these methods would pave the way to the advancement of new drugs with unique efficacy and tolerability properties.     

Bulgarian Bone Marrow Donors Registry—past and future directions

Recently Bulgarian Bone Marrow Donors Registry (BBMDR) has been established and since August 2005 it has been a member of Bone Marrow Donors Worldwide. Currently the number of healthy donors included in the BBMDR is relatively low. All donors included in the BBMDR are typed for HLA-A, -B, -DRB loci. Phylogenetic analysis based on HLA allele frequencies shows that Bulgarians were characterized with closest genetic similarity to Macedonians, Greeks, Romanians, Cretans and Sardinians in comparison to the other European and Mediterranean populations. On the contrary the second largest ethnic minority–the Roma were the closest to the other Roma populations and North Indians. These differences were due to the predominance of alleles and haplotypes that are specific for the Asian and the other Roma populations. These specific genetic profiles in the Bulgarian ethnic minorities justify the need of an adequate representation of minorities in BBMDR. Future directions for BBMDR development are discussed, including an increase of the total number of donors and these for ethnic minorities, as well the enhancement of the level of resolution of the HLA typing for the donors in the registry.     

Meta-analysis and research on host–parasite interactions: past and future

Host–parasite interactions are characterised by a lack of stable species-specific traits that limits generalisations one can make even about particular host or parasite species. For instance, the virulence, life history traits or transmission mode of a given parasite species can depend on which of its suitable hosts it infects. In the search for general rules or patterns, meta-analysis provides a possible solution to the challenges posed by the highly variable outcomes of host–parasite interactions. It allows an estimate of the overall association between any factor and its biological response that transcends the particulars of given host and parasite taxonomic combinations. In this review, we begin with a historical overview of the use of meta-analysis in research on the ecology and evolution of host–parasite interactions. We then identify several key conceptual advances that were made possible only through meta-analytical synthesis. For example, meta-analysis revealed the predominant association between rates of host and parasite gene flow and local adaptation, as well as an unexpected latitudinal gradient in parasite virulence, or parasite-induced host mortality. Finally, we propose some areas of research on host–parasite interactions that are based on a mature theoretical foundation and for which there now exist sufficient primary results to make them ripe for meta-analysis. The search for the processes causing variability in parasite species richness among host species, and the link between the expression of host resistance and the specificity of parasites, are two such research areas. The main objective of this review is to promote meta-analysis as a synthetic tool overriding the idiosyncrasies of specific host–parasite combinations and capable of uncovering the universal trends, if any, in the evolutionary ecology of parasitism.     

Mariculture in Israel – past achievements and future directions in raising rotifers as food for marine fish larvae

Marine fish production is now being carried out afteralmost two decades of research. The production ofseabream (Sparus aurata), which reached over 750tons in 1995, is expected to reach an annualproduction ranging between 4000 - 12 700 metric tonsby year 2010. The anticipated introduction of newspecies and its expansion to the Mediterranean shoreline will help in leading the increased maricultureproduction. Two marine fish hatcheries that operatetoday in Israel produce 7 million fingerlings a year.Traditionally, aquaculture in Israel raises fish ininland freshwater ponds and irrigation reservoirs. Inaddition, Lake Kinneret, the only freshwater lake inIsrael, is stocked yearly with juvenile fish raised inlocal hatcheries (tilapia) or imported fromMediterranean countries (mugil). While culture offreshwater teleost species (carp) was introduced morethan fifty years ago, mariculture started on acommercial scale less than 5 years ago. The limitedsupply of freshwater will accelerate the futureculture of marine species.The bottleneck of almost all marine finfish productionlies in obtaining adequate numbers of fingerlings, dueto their high mortality at early life stages. Theproduction is hindered by inadequate supply of food toearly larval stages which require live food.Development of technologies in Israel for masscultivation of food chain organisms including algae,rotifers and brine shrimp followed their developmentin other parts of the world, most notably thoseachieved in Japan. The local commercial scaleproduction of rotifers relies on several batch orsemi-continuous cultures in conical or flatbottomrectangular containers that supply daily 0.6-4billion rotifers in each hatchery. Originally arelatively large local Brachionus plicatilisstrain was used, but later smaller B.rotundiformis strains were introduced, resulting ina mixture of undefined strains. The incorporation ofalgae (Nannochloropsis sp.) generated in highyield raceways contributes to the reliability ofrotifer cultures. Algae are supplied directly from theraceways or centrifuged and stored as a frozen pasteuntil required in the hatchery. The current dependablesupply of live cultures reduces the need for preservedstocks of rotifers, either as resting eggs or keptalive at low temperatures. To the fish grower,rotifers are live food capsules that deliver essentialnutrients (e.g. long chain unsaturated fatty acids)for growth and survival of fish larvae. Research aimedat replacing live food with chemically definedmicrodiets could reveal physiological principles inprey recognition and digestion of food by marine fishlarvae.