Science as a Way of Knowing--Genetics

SYNOPSIS. This essay is part of the third presentation of aneducational project of the American Society of Zoologists. Thepurpose is to offer suggestions for improving the first-yearbiology courses in the universities. The method consists ofemphasizing the conceptual framework of the biological sciences,showing how scientific information is obtained and evaluated,pointing out the strengths and limitations of scientific procedures,and above all showing the relevance of science for human hopesand well being. This is done annually with a major symposium,an essay distributed at the symposium, a film program, and,finally, the published proceedings, which are widely distributedto scientistteachers throughout the world. Each year a majortopicis considered. In 1983 it was Evolutionary Biology andin 1984 it was Human Ecology. This year it is Genetics.     

Science as a way of knowing--form and function

Synopsis. These essays are part of the fifth yearly presentationof an educational project of the American Society of Zoologists.The purpose is to provide background materials for those whoteach the first-year biology courses in colleges and universities.The Science as a way of knowing project emphasizes the conceptualframework of the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is the broadest so farattempted—form and function. These introductory essaysare concerned mainly with the conceptual framework of morphologyand physiology as it developed over the ages.     

A Conceptual Framework for Biology Part I

These essays are part of the sixth yearly presentation of aneducational project of the American Society of Zoologists. Thepurpose is to provide background materials for those who teachthe first-year biology courses in colleges and universities.The Science as a Way of Knowing project emphasizes the conceptualframework of the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is Cell and MolecularBiology.     

Long-range Perspectives on Neurobiology and Behavior

This essay is part of the seventh presentation of a yearly educationalproject of the American Society of Zoologists. The purpose isto provide background materials for those who teach the first-yearbiology courses in colleges and universities. The Science asa Way of Knowing project emphasizes the conceptual frameworkof the biological sciences, shows how scientific informationis obtained and validated, and relates science to human concerns.The topic for consideration this year is Neurobiology and Behavior.The introductory essay is concerned mainly with the conceptualframework of neurobiology, as developed over the ages, and afew examples of behavioral studies which can be related to neurobiologyor which are of special interest through links to human considerationsand problems.     

Modelling the Masting Behaviour of Betula platyphylla var. japonica using the Resource Budget Model

A masting model of Betula platyphylla var. japonica, a majorwind-pollinated tree in Hokkaido, northern Japan, was constructedfrom the perspective of the resource budget model. An 11-yeardata series of pollen dispersal by birch showed marked annualfluctuations in flowering. Although flowering fluctuated widelyamong years, a reciprocal relationship was observed betweentwo consecutive years; very little flowering occurred aftera mast year. This suggests that there is a negative relationshipbetween current fruiting and flower bud induction. There wasa significant positive relationship in flowering between regions,which suggests that weather conditions regulate flowering inbirch. A model that included weather variables and resourceallocation systems among years explained 94·5% of theobserved annual fluctuations in flowering. In the model, warmspring conditions from bud burst to flower bud development andlittle flowering in the previous year (t-1) resulted in increasedflowering in the current year (t), whereas abundant floweringin year t-2 resulted in a decrease in flowering in the currentyear (t). The latter indicates that flowering in year t-2 affectsresource storage after overwintering; the balance is carriedforward to year t-1 and affects the initiation of flower primordiabefore bud burst. In the model, fluctuating weather conditionsin the previous spring strongly affected the masting behaviourof birch. Copyright 2001 Annals of Botany Company Betula platyphylla var. japonica, flowering, masting, modelling, pollen dispersal, resource allocation, resource budget model, weather conditions     

THE ECOLOGY OF THE HONG KONG LIMPETS CELLANA GRATA (GOULD, 1859) AND PATELLOIDA PYGMAEA(DUNKER, 1860): DISTRIBUTION AND POPULATION DYNAMICS

Cellana grata is a high-zoned, exposed-shore limpet with a lifespanof 3 years. Patclloida pygmaeais a low-zoned, sheltered-shorelimpet with a lifespan of I year. C. grata migrates up-shorein winter, but occurs lower on the shore in summer. This migrationis synchronized with variations in algal availability high onthe shore; such variations are, however, themselves relatedto seasonal changes in wave height. P. pygmaea is restrictedto the low shore, year round. The movements upwards in winterand downwards in summer are still evident. Algal species richnessincreased from September to reach a peak between December andMarch, and to abruptly diminish between May and June. The encrustingalgae Brachytrichia maculans, Hildenbrandia prototypus, Lithothamnionsp. and Ralfsia vcrrucosa were present year round. The timingof juvenile recruitment of C. grata and P. pygmaea was fromOctober to July and February to October, respectively. Temperaturemay be important in enhancing juvenile survival by affectingthe seasonal pattern of algal occurrence on the shore. Seasonalfluctuations in the rate of growth were recorded for both specieswith the time of fastest growth of C. grata and P. pygmaea occurringbetween October and March and September and February, respectively.Mortality of both species occurred mainly in summer. Summerheat, predation and intra-specific competition for food appearto be the major causes of death. (Received 1 December 1992; accepted 5 May 1993)     

Wheeler, E.A. and Manchester, S.R. Woods of the Eocene nut beds flora, Clarno Formation, Oregon, USA. IAWA Journal, Supplement 3

IAWA (International Asso ciation of Wood Anato mists) publishesa high quality journal in four parts, comprising about 500 pagesa year. Every so often they publish supplements that are muchlonger and more comprehensive than traditional scientific papers.The first two were Bibliography of systematic wood anatomy ofdicotyledons (265 pages) by Mary Gregory (1994) and Wood anatomyof Sapindaceae (214 pages) by René Klaasen (1999). Thisthird supplement is on a fossil flora which has many well-preservedwoods that have now been studied in detail. The only minor criticismI have is that the title of     

An Analysis of Growth Rates in the Early Life of Apple Trees

A long-term continuing experiment to study the effect of rootstockand pruning on composite apple trees is described. Cox's OrangePippin was worked on to either M·26 or MM·104rootstocks. Two pruning regimes were applied to give a totalof four treatments. The course of whole plant growth expressed by the cumulativedry weight during the first 9 years is described by means ofgrowth curves. Special reference is made to the growth and functionof the perennial structure, and its contribution to whole plantgrowth is quantified by means of the parameter Unit ProductionRate. This expresses the rate of growth per unit weight of theperennating structure. Unit Production Rate declined with increasingtree age; in the first 5 years spur pruning and invigoratingrootstock treatments gave the highest values whilst later thissituation was reversed. The efficiency of the process of perennation is quantified interms of the production rate of the deciduous fraction per unitweight of the perennating structure. In this respect dwarfingrootstock treatments were appreciably superior to invigoratingrootstock treatments only after the fifth year. Spur pruninggave lower values than minimal pruning at 7 years with spur-prunedCox/MM·ro4 alone showing a decline with increasing ageafter 5 years.     

First report of the presence of Acartia margalefi (Copepoda: Calanoida) in Southampton Water and Horsea Lake, UK

Acartia margalefi is recorded for the first time in Britishwaters, where it is found to be an important copepod in themesozooplankton community structure of Southampton Water andHorsea Lake. Within the genus Acartia. this species occurs allthrough the annual cycle. Abundance is higher in the upper estuary,where the range of temperature and salinity is relatively widerover the year. It is clear that A.margalefi is an estuarinespecies which can tolerate a significant range of temperature.     

The role of temperature in the seed germination of two species of the Solanum nigrum complex

The germination behaviour of S. nigrum L. and S. physalifoliumRusby var. nitidibacatum (Bitter) Edmonds is compared, basedon temperature requirements during imbibition. Three seed lotsof S. nigrum had base temperatures (T_b) between 7.5C and 10C,showing a lower T_b when the period of freezing days, duringwhich each population was collected, was reduced. S. physalifoliumhas a higher value for T_b at constant temperatures (21C) thatcan be interpreted as a dormancy constraint. This constraintis released by alternating temperatures at amplitudes exceeding5C and with the high temperature above 21C by apparently reducingT_b to 12.5C. This implies that for S. physaiifolium temperature has a dualeffect on germination. It is the driving force for changes indormancy, but germination also depends on the temperature. Therole of temperature for S. nigrum is simpler: each populationcollected showed differences in the thermal time required forgermination that could be related to the temperature regimenof the original environment. Key words: Dormancy, S. nigrum, S. physalifolium, thermal time     

Observations on the Biology of Fomes annosus, with Particular Reference to East Anglian Pine Plantations: II. Spore Production, Stump Infection, and Saprophytic Activity in Stumps

F. annosus produces conidia abundantly in culture but rarelyunder natural conditions. Sporophorea are formed on stumps anddying trees throughout the year provided that the humidity issufficiently high. Spore discharge in the plantations may occurat any time of year, but slowa down or ceases during very dryweather. It takes place at low temperatures, ceasing only whensporophores freeze. In the laboratory, F. annosus basidiospores germinate in relativehumidity exceeding 92 per cent. on freshly cut, unsterilizedpine wood. Viability is lost rapidly in light at temperaturesabove 15°C. Under humid conditions F. annosus spores will infect freshlycut pine stumps. There is evidence that spores of F. annosus washed down intosoil remain viable for at least a short period and that stumpscovered with soil are infected from this source. F. annosusspores can infect stumps for only a few weeks after felling,colonization after a longer interval probably beingprevdntedby competing fungi. In stumps inoculated with a mixed suspensionof F. annosus and Peniophora gigantea spores, Fomes at firstcolonized the wood but was soon replaced by P. gigantea. Otheraspects of competition are discussed. The incidence of natural infection in stumps and the factorsaffecting it are discussed Growth rates of F. annosus on malt agar and in lengths of pineroot are given. The fungus grows in stump roots at about 1 m.per year, and so closely approaches adjacent trees within ayear of thinning the plantation: In large stumps, F. annosusmay survive 15 or even 30 years after felling. Data are givenwhich suggest that the infective capacity of stumps containingF. annosus is greater in alkaline than in acid mils, while replacementby other fungi is slower. Competition of F. annosus with other fungi during colonizationof stumps is discussed. The parasite can grow along roots alreadyoccupied by certain fungi but not along roots containing others.The probable course of succession in stumps rotted by F. annousis described.     

荒漠昆虫光滑鳖甲的耐寒性季节变化及其生理机制

光滑鳖甲Anatolica polita borealis生活于温差大的新疆荒漠环境, 为探讨其耐寒性及耐寒机制, 本研究测定了其3-9月份成虫在－10℃的耐寒性、过冷却点（SCP）、含水量、甘油含量和血淋巴热滞活性(thermal hysteresis activity, THA)以及冷驯化对增强光滑鳖甲成虫耐寒性的效果, 还测定了光滑鳖甲不同发育阶段幼虫的SCP。结果表明: 光滑鳖甲成虫的耐寒性和SCP具有明显的季节性变化, 3月初SCP为－12.5℃, 7月为－6℃, 9月底为－13.6℃。4℃冷驯化能够提高光滑鳖甲成虫在－10℃的存活率, 未驯化组在40 min的存活率为50%, 而驯化2 h的为70%, 驯化24 h的为90%。虫体含水量在夏季有显著降低, 3月、7月和9月结合水与自由水的比值分别为10.8∶1,2.6∶1和5.4∶1。成虫甘油含量与SCP的回归方程为y=－0.6204x－5.681, R²=0.7714。成虫血淋巴THA与过冷却点的回归方程为y=－5.26x－1.713, R²=0.9049。血淋巴THA比甘油浓度更能影响过冷却点降低的程度。随着幼虫的发育, 其SCP逐渐降低。结果提示, 光滑鳖甲通过提高结合水与自由水的比值、增加抗冻蛋白和甘油的含量使虫体保持较低的SCP, 因而具有较高的耐寒性。     

中国特有的弯头果蝇种亚组及二新种记述(双翅目，果蝇科)

本文记述弯头果蝇种亚组的二新种,施氏果蝇 Drosophila (Drosophila) shi sp. nov.,短乳突果蝇Drosophila (Drosophila) brevipapilla sp.nov.,并对中国特有的弯头果蝇种亚组中11 个种的分布进行了分析。     

SYNCHRONIZATION OF BACTERIAL CULTURE BY PREINCUBATION OF CELLS AT HIGH CELL DENSITY

The growth of Escherichia coli strain B in a liquid medium wasfound to cease at a cell density of 5x10⁹ cells per ml. (Thiscritical concentration is designated as the maximum or M-concentration.)Even cells harvested from the logarithmic growth phase couldnot divide at this or higher cell densities. Investigationson the metabolic activities of such cultures, however, showedthat the synthesis of cellular protein and nucleic acid wastaking place under such circumstances, showing that only someprocess (or processes) particularly related to cell divisionwas suppressed at the critical cell concentration in question. This finding led us to devise a new method of synchronizationof E. coli: cells harvested from a logarithmic phase were preincubatedat the critical concentration of 5x10⁹ cells per ml for 45 minutes,and then diluted 100 times with fresh medium. This led to synchronizationof cell division, as shown by a stepwise multiplication in cellnumber. (Received June 20, 1961; )     

The capacity for change and the unpredictability of the phytoplankton of the east coast of the United States

Differences in the change of numerical abundance from time totime through the year and place to place along the U.S. eastcoast show Skeletonema costatum to have a greater capacity forchange than Thalassionema nitzschioides. These differences emergefrom the unpredictable occurrence and absence of Skeletonemafrom time to time through the year and from year to year atWoods Hole and from place to place along the U.S. east coast.Skeletonema's greater capacity for change than Thatassionema'stransmit an inherently variable capacity for change to the wholephytoplankton, and the unpredictability of these species transmitsthis characteristic to the whole population too.     

Size structure of plankton in a temporary, saline inland lake

The study of the size structure of a planktonic community ina relatively extensive (1350 ha), very shallow (0.46 m maximumdepth), temporary inland saline lake during a relatively rainyyear (1987–88) showed an average biomass-size spectrumwith four clear modes at nano-, micro-, meso- and macroplanktonsize ranges. The size-abundance distribution was dominated bymedium-sized phytoplankton cells (Gymnodinium cf. excavatum,Tetraselmis apiculata, Dunaliella spp. and several diatom species),large ciliates (Fabrea salina) and a few zooplankton speciesadapted to changing temporary environments within a wide sizerange (Cletocamptus retrogressus, Moina salina, Branchinellaspinosa). This polymodal size distribution is compared withresults obtained in other systems, including small physicallycontrolled lakes, large lakes, oceans and marine benthos. Considerationof the size structure within homogeneous groups of organismsshows slopes less negative than the average for the whole sizerange analysed, a feature which is common in small and physicallycontrolled ecosystems. A seasonal study of the size structurerevealed uneven distributions throughout the year, resultingin discontinuities in the size spectra as well as in differencesof total size range. There were noticeable differences amongthe size spectra at each particular time, showing phases ofprimary producer predominance and phases with a marked predominanceof consumers. The time-integrated size spectrum did not exhibitany distinct discontinuity. The influence of extreme shallownessand resuspension on the shape and dynamics of the size spectrumis examined and discussed compared to deeper aquatic systems.     

Interannual variability in the distribution of the phytoplankton standing stock across the seasonal sea-ice zone west of the Antarctic Peninsula

The spatial distribution of phytoplankton cell abundance, carbon(C) biomass and chlorophyll a (Chl a) concentration was analysedduring three summers (1996, 1997 and 1999) in a seasonal sea-icearea, west of the Antarctic Peninsula. The objective of thestudy was to assess interannual variability in phytoplanktonspatial distribution and the mechanisms that regulate phytoplanktonaccumulation in the water column. Phytoplankton C biomass andChl a distributions were consistent from year to year, exhibitinga negative on/offshore gradient. The variations in C concentrationhad a close and non-linear relationship with the upper mixedlayer depth, suggesting that the vertical mixing of the watercolumn is the main factor regulating phytoplankton stock. Themagnitude of C gradients was 5-fold higher during 1996 thanduring 1997 and 1999. This was ascribed to interannual variationsin the concentration of diatom blooms in the region influencedby sea-ice melting. Vertical distribution of the phytoplankton,as estimated from Chl a profiles, also varied along an on/offshoregradient: Chl a was distributed homogeneously in the upper mixedlayer in coastal and mid-shelf stations and concentrated inthe deep layer (40–100 m) occupied by the winter waters(WW, remnants of the Antarctic surface waters during summer)in more offshore stations. The region with a deep Chl a maximumlayer (DCM layer) was dominated by a phytoplankton assemblagecharacterized by a relatively high concentration of diatoms.The extent of this region varied from year to year: it was restrictedto pelagic waters during 1996, extended to the shelf slope during1997 and occupied a major portion of the area during 1999. Itis hypothesized that iron depletion in near surface waters dueto phytoplankton consumption, and a higher concentration inWW, regulated this vertical phytoplankton distribution pattern.Furthermore, we postulate that year-to-year variations in thespatial distribution of the DCM layer were related to interannualvariations in the timing of the sea-ice retreat. The similaritybetween our results and those reported in literature for otherareas of the Southern Ocean allows us to suggest that the mechanismsproposed here as regulating phytoplankton stock in our areamay be applicable elsewhere.     

EDITORIAL

The Annals of Botany, one of the oldest botanical journals incontinuous publication, publishes eclectic and innovative papers,both on-line and in print, in almost every sphere of plant biology.Its policy has been and remains to improve and develop all aspectsof the Journal’s provision for the benefit of authorsand readers alike. In doing so, it aims to meet fully theirdemands for a high level of originality in scientific content,top quality reproduction and prompt publication with wide accessibility.Annals of Botany faces these