Glycosylation sites identified by solid-phase Edman degradation: O-linked glycosylation motifs on human glycophorin A

The human red blood cell sialoglycoprotein, glycophorin A (GpA),contains a ‘mucin-like’ extensively O-glycosylatedextracellular domain which carries the MN blood group antigens.We have revised the sites of O-glyccsylation in the extracellulardomain of GpA by automated solid-phase Edman degradation, whichallowed positive identification and quantitation of O-glycosylatedSer and Thr residues, as well as the single N-glycosylationsite. One N-linked and 16 O-linked sites were identified. Carbohydratewas absent on Ser 1, Ser14, Ser15, Ser23, Thr28 and Thr58 inGpA. We propose that the glycosyltransferases present in erythrocytesrecognize specific flanking sequences around potential O-glycosylationsites. All 16 O-glycosylation sites are explained on the basisof four motifs. Three motifs are associated with Thr-glycosylation:Xaa—Pro—Xaa—Xaa where at least one Xaa = Thr;Thr—Xaa—Xaa—Xaa where at least one Xaa = Thr;Xaa—Xaa—Thr—Xaa where at least one X = Argor Lys. The fourth motif is associated with Ser-glycosylation:Ser—Xaa—Xaa—Xaa where at least one Xaa = Ser.These simple rules explain the glycosylation (or lack of it)on 21 of 22 Ser/Thr in the extracellular domain of GpA. glycophorin A O-glycosylation motif solid-phase Edman degradation     

Physical Analysis of Tissue Mechanics in Amphibian Gastrulation

During morphogenesis, intercellular attachments constrain cellmobility so that embryonic tissues may (i) deform as solid sheetsof tightly bound cells, (ii) disperse to migrate as separatecells or (iii) flow as multicellular liquids (in which cellsremain aggregated yet can still slide past one another). Bymodelling deep germ layers as multicellular liquids in amphibiangastrulation, Davis and I have predicted, and then confirmedexperimentally, (i) the area-invariance of deep-germ-layer surfacetensions in vitro, (ii) spontaneous cell slippage in deformeddeep—germ—layer cell aggregates and (iii) correlationsof tissue surface tensions with tissue positioning in deep-germ-layercell-sorting and aggregate—fusion experiments. Liquid—tissueflow involves intercalations of interior cells into expandingtissue interfaces (or withdrawal of surface cells from shrinkingtissue interfaces). Tissue surface tensions are macroscopicreflections of the microscopic, tissue—specific adhesivedifferentials which direct these cell translocations. Such adhesivedifferentials may act independently of, or together with, activecell—shape changes, chemotaxis, contact guidance and/orhaptotaxis in controlling embryonic tissue rearrangements. Deepcell intercalations in vivo occur throughout amphibian gastrulation:during ectodermal epiboly; during marginal—zone extensionand convergence (and therefore blastopore closure); during mesodermalinvolution; and probably during the anterior spreading and axialextension (and therefore dorsal convergence) of involuted mesoderm.Tissue—surface—tension measurements may help determine(i) which of these cell—intercalation processes are activeand which are passive, (ii) the specific contributions of variousmicroscopic cell properties to the regulation of liquid—likegerm—layer assembly and (iii) similarities and differencesbetween in vitro and in vivo control mechanisms governing amphibiangastrulation.     

Mineral nutrition, of cultured chlorophyllous cells of tobacco VII. Effects of the NH4/NO3 ratio and of Cl in the media on the growth and ionic balance of cells

NG, a strain of cultured tobacco cells of Nicotiana glutinosahad high growth rates and carboxylate contents (C—A) of100 to 130 meq/100 g of dry cells on media containing 42 meqNO₃/liter as the sole N source. (C—A) is the amount ofinorganic cations minus inorganic anions in meq per 100 g ofdry cells. NG, cultured on media containing NH₄ 10+NO₃ 42 in meq/liter,had lower growth rates and lower (C—A) values as comparedwith NG on media containing NO₃ as the sole N source. NG, cultured on media containing NH₄ 30+NO₃ 42 in meq/liter,had high growth rates and (A—C) values of 22 to 53 meq/100gof dry cells. In this case, the (A—C) content may correspondto organic cations, basic organic N compounds such as free asprotein-bound basic amino acids. The easily absorbed Cl mayhave been required maintain good growth conditions such as ionicbalance and a favorable pH in the cells. Thus cultured cells of Nicotiana glutinosa may have physiologicaladaptability against variations in a relatively wide range of|C—A| contents [|C—A| being the absolute valuesof (C—A)]. (Received May 15, 1980; )     

Freezing avoidance mechanism of primordial shoots of conifer buds

Excised winter buds of very hardy fir supercooled to —30or — 35?C, though primordial shoots excised from thesewinter buds (freezing point: about —5.5?C) supercooledonly to —12 to — 14?C. Also, excised primordialshoots did not tolerate freezing, but were rather resistantto desiccation. Differential thermal analysis (DTA) of primordialshoots revealed that the capability of supercooling increasedwith decreasing water content and that no exotherm could bedetected in the primordial shoots with a water content belowabout 20%. When excised whole buds were cooled very slowly,the exotherm temperature shifted markedly to a lower value andthe exotherm became much smaller. Also, masses of needle icewere observed, mainly beneath the crown of the primordial shoot.From these results, it may be concluded that most of the waterin primordial shoots gradually migrates out through the crownand freezes as the temperature decreases (extraorgan freezing),which enables primordial shoots to survive at very low temperatures.Winter buds of Abies balsamea held at — 20?C for 30 daysand then slowly cooled down to —50 or —60?C remainedalive. Thus, there seems to be no low temperature limit to thisfrost avoidance mechanism, if the primordial shoots can resistintensive freeze-dehydration. Low temperature exotherms wereobserved in all genera which belong to Abietoideae and Laricoideaeof Pinaceae, all of which have a crown in the primordial shoots,but not in other conifers. ¹ Contribution No. 2037 from the Institute of Low TemperatureScience. (Received June 25, 1979; )     

A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge,Tanzania

Background

The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular “horns” over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus.

Methodology/Principal Findings

The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma), in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus.

Conclusions/Significance

The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus.     

Tertiary crocodylians from Puerto Rico: Evidence for Late Tertiary endemic crocodylians in the West Indies?

Fragmentary fossils from northwestern Puerto Rico document the existence of crocodyliforms during the Late Oligocene and Early Miocene. The remains are insufficient to establish new named species, but they are inconsistent with any other crocodylian known from the western hemisphere during the Cenozoic, including extant Alligator and Crocodylus. They are thus consistent with the hypothesis that Crocodylus is a comparatively recent immigrant into the West Indies and suggest that, as with Australasia and Africa, the Antilles hosted an endemic clade of crocodylians during the Tertiary, later replaced by Crocodylus.     

The rotifers of Warri River, Nigeria

The rotifer assemblage of the dendritic tidal Warri River wasinvestigated at four sampling points from July 1981 to July1982. Forty-one species of Rotifera were identified. Five ofthese — Anuraeopsis racenesi Berzins Keratella cochlearismacracantha Lauterbom, Monostyla lunaris Pawlowsky,M. stenroosiMeissner and Trichocerca similis grandis Hauer — are beingrecorded for the first time in West Africa. The Warri Riverrotifers are 65% cosmopolitan and 20% pantropical although therewas no species limited to African waters only. The dominantrotifers in the Warri River were Keratella tropica and K. cochleariswhich were found in the predominantly freshwater sampling stationat Udu Bridge to Warri and Orugbo Creek where low brackish watersalinities and conductivities are observed from December orJanuary to April each year. The preponderance and longitudinaldistribution of these two well-known cyclomorphic rotifers providesan opportunity to study their salinity tolerance and the effectof salinity and conductivity on their cyclomorphosis by samplingalong the length of the river from Udu Bridge to Forcados wherethe Warri River joins the Atlantic Ocean.     

Growth and Dry-weight Distribution in Callistephus chinensis as Influenced by Lighting Treatment

Plants of two cultivars of Callistephus chinensis (Queen ofthe Market and Johannistag) were grown in 8 h of daylight perday with one of the following treatments given during the 16h dark period: (a) darkness—‘uninterrupted night’,(b) I h of light in the middle of the dark period—a ‘nightbreak’, (c) I min of light in every hour of the dark period—‘cycliclighting’, (d) light throughout—‘continuouslight’. The plants receiving uninterrupted dark periods remained compactand rosetted in habit with small leaves, while leaf expansion,stem extension, and flower initiation were promoted in all threeillumination treatments (b, c, d). Although these three treatmentsproduced similar increases in leaf area, continuous light wasthe most effective for the promotion of both stem growth andflower initiation while cyclic lighting was generally more effectivethan a I-h night break. Continuous light also caused more dry matter to be divertedto stems at any given vegetative dry weight and it was shownthat the stem weight ratio of both varieties was correlatedwith stem length.     

Reproductive skew and group size: an N-person staying incentive model

Transactional models of social evolution emphasize that dominantbreeders may donate parcels of reproduction to subordinatesin return for peaceful cooperation. We develop a general transactionalmodel of reproductive partitioning and group size for N-persongroups when (1) expected group output is a concave (decelerating)functiong[N] of the number N of group members, and (2) thesubordinates may receive fractions of total group reproduction("staying incentives") just sufficient to induce them to stayand help the dominant instead of breeding solitarily. We focusespecially on "saturated" groups, that is, groups that havegrown in size just up to the point where subsequent joining by subordinates is no longer beneficial either to them (in parent-offspring groups) or to the dominant (in symmetric-relatedness groups).Decreased expected output for solitary breeding increases thesaturated group size and decreases the staying incentives.Increased relatedness decreases both the saturated group sizeand the staying incentives. However, in saturated groups withsymmetric relatedness, an individual subordinate's staying incentive converges to 1 — g[N^* — 1]/g[N^*]) regardless ofrelatedness, where N^* is the size of a saturated group, providedthat the g[N] function near the saturated group size N^* isapproximately linear. Thus, staying incentives can be insensitiveto relatedness in saturated groups, although the dominant's total fraction of reproduction (total skew) will be more sensitive.The predicted ordering for saturated group size is: Parent-fullsibling offspring = non-relatives > symmetrically relatedrelatives. Strikingly, stable groups of non-relatives can formfor concaveg[N] functions in our model but not in previousmodels of group size lacking skew manipulation by the dominant.Finally, symmetrical relatedness groups should tend to breakup by threatened ejections of subordinates by dominants, whereas parent-offspring groups should tend to breakup via unforceddepartures by subordinates.     

The response of tomato roots (Lycopersicon esculentum Mill.) to iron deficiency stress: alterations in the pattern of protein synthesis

Dicotyledon plants adapt to iron (Fe) deficiency through a seriesof reactions that increase the ability of the plant to assimilateFe and to increase the efficiency of Fe utilization. In an attemptto gain an insight into these adaptive processes, the specificchanges in protein synthesis associated with the onset of theFe deficiency response in tomato roots (Lycopersicon esculentumMill cv. Rutgers) have been investigated. Roots were grown underFe—sufficient and —deficient conditions, and thepattern of protein synthesis was analysed by in vitro translationof root mRNA and by in vivo labelling of root proteins. Polypeptideswere resolved by two—dimensional polyacrylamide gel elec—trophoresis.Seven polypeptides were identified by in vitro translation,whose synthesis was significantly increased during Fe deficiency.The increase was probably specific to Fe deficiency in thatthe polypep—tide synthesis was not increased during phosphatedeficiency stress, was less prominent following prolonged Fedeficiency and was decreased following re—supply of Feto the hydroponic medium. The pattern of in vitro translation of mRNA isolated from Fe—deficientroots was compared to the results obtainedin vivo followingradiolabelling of proteins. In these analyses, eight polypeptideswere identified, tentatively including the seven polypeptidespreviously identified by in vitro translation. All polypeptideswere characterized with regard to molecular mass and pl andtheir localization in the cell, whether being membrane boundor soluble. It is suggested that members of this group of polypeptidesare involved in the response of the root to Fe deficiency: althoughtheir functions remain to be identified. Key words: In vitro protein synthesis, iron, iron deficiency, root, 2-dimensional PAGE     

Grazing of echinoderm larvae (Paracentrotus lividus and Arbacia lixula) on naturally occurring particulate matter

Larvae (72 hr old) of P. lividus and A. lixula grazed on varioussuspensions of natural particulate matter with a size rangeof 2 to 30 microns, and on two species of algae (Phaeodactylumtricor-nutum and Nitzschia sp.) — Larvae graze most in the size range where the particleconcentration is highest. — If larvae deplete certain size categories of particlesthey then graze other size ranges in which the concentrationis still high. — The grazing rate of the two species varied between 988and 91.949 µm³ per pluteus per hour. — For A. lixula larvae the grazing rate increases withincreasing temperature to a maximum at 22°C.     

UPPER BARREMIAN (CRETACEOUS) HETEROCERATID AMMONITES FROM SOUTH AFRICA AND THE CAUCASUS AND THEIR -PALAEOBIOGEOGRAPHIC SIGNIFICANCE

Heleroceratid ammonites are abundant in the Upper Barremiansediments of Zululand, South Africa, and representatives ofthe genera Heteroceras, Colchidites and Paraimerites are describedbelow. This assemblage shows strong similarities to faunas knownfrom the Caucasus region of the USSR, a similarity that persistedinto the succeeding Aptian. This similarity presents somethingof a paradox, because the genera concerned are among the leasthydrodynamically streamlined of ammonites. Their distributionsuggests an open marine connection between the Mediterraneanparts of Tethys and the eastern coast of Africa, linked, inthe Barremian — early Aptian at least, to Patagonia. Theirwide distribution also supports the view that climatic gradientswerelow during the Barremian and that the climate was generallywarmer than at present. (Received 12 January 1983;     

Algorithm and computer program Pro--Anal for analysis of relationship between structure and activity in a family of proteins or peptides

In this paper we introduce a computer algorithm and programPro—Anal for analysis of the structure-activity relationshipin a family of evolutionarily related (and/or artificially mutated)proteins/peptides. The program uses aligned amino acid sequenceswith data of their activity (pK, K_m, ED₅₀ or any other) andsearches for correlations between data on activity and variousphysico-chemical characteristics of different regions in primarystructures. In automatic mode, the program generates and verifieshypotheses on the disposition of a sequential modulating regionin a protein, and key characteristics of the region. In manualmode, users can generate and analyze their own hypotheses. Theprogram is implemented on IBM PC or compatible computers. Itis designed to be easily handled by the occasional computeruser and yet it is powerful enough for experienced professionals.Pro—Anal operation is demonstrated on the example of findingmodulating centers in a family of disintegrins—proteinsfrom snake venoms which inhibit fibrinogen interaction withplatelet receptors. In another example it is shown that theimmunogenicity of peptides is connected with their positivecharge.     

Colony Specificity in the Colonial Tunicate Botryllus and the Origins of Vertebrate Immunity

SYNOPSIS. Colonies of the compound tunicate Botryllus show thecapacity for self—nonself discrimination by fusion betweenseparated pieces of the same colony and rejection between piecesof unrelated colonies. We have found that genes controllingthis colony specificity are similar to those which cause transplantrejection in the vertebrates. Like the loci within the vertebratemajor histocompatibility complex (MHC), Botryllus fusibility(or histocompatibility) genes are highly polymorphic. In Botryllus,the histocompatibility complex also controls self—sterility,and limits cross—fertilization between colonies sharinghistocompatibility alleles. The mouse MHC, the H-2 region, islinked to loci which also affect the frequencies of allelesat H-2 loci in mouse populations. Thus both systems containcharacters which could act to promote the heterozygous conditionat the linked histocompatibility loci. We suggest that suchlinked characters are responsible for the evolution of allogeneicpolymorphism in vertebrates (however currently maintained),and that tunicate fusibility loci may be the evolutionary precursorsof vertebrate MHC genes.     

Fine Structure of Hydrolysed Primary Walls in Tracheary Elements of Petiolar Xylem in Eucalyptus delegatensis

The hydrolysed lateral primary walls of tracheary elements ofthe petiolar xylem of Eucalyptus delegatensis were examinedby electron microscopy. Vessel-vessel and vessel—tracheidhydrolysed walls were strikingly different in appearance fromtracheid—tracheid walls. The difference seemed to be inthe degree to which the primary walls were hydrolysed. The observationssuggest the wall hydrolysis to be an ordered and controlledprocess. Eucalyptus delegatensis, hydrolysed wall, petiolar xylem, tracheary elements     

Some Complicating Factors in the Study of the Calcium Metabolism of Teleosts

A number of factors which may complicate studies dealing withthe calcium metabolism of teleosts are pointed out. Thus, lowenvironmental levels of calcium markedly affect both gill RNAand sodium metabolism in dilute sea water, and the absence ofmonovalent cations affects calcium metabolism in dilute environments.Hypophysectomy is not always followed by the disappearance ofcortisol from the plasma, and prolactin—which is requiredfor the survival of either hypophysectomized or intact animalsin a divalent ion-free environment—stimulates cortisolproduction. It is also pointed out that Fundulus kansae can be maintainedin divalent ion-free environments for long periods, and thatcalcium is mobilized from internal reservoirs such as acellularbone and scales. Failure to survive in such environments isdue to the regulatory effect of environmental calcium on sodiummetabolism rather than on calcium metabolism per se. Finally,it is pointed out that while one parameter of calcium metabolism—suchas plasma calcium levels in male fish—may remain constantthroughtout the year, other parameters such as calcium uptakemay vary considerably. Seasonal differencees in responses tomammalian calcitonin have also been noted.     

Sexuality in Diploid and Hexaploid Races of Mercurialis annua L

The variation in sex expression found between individuals ofMercurialis annua agg. is described, distinction being madebetween ‘regular’ and ‘irregular’ monoecism.There is shown to be a relationship between sexuality, morphology,and chromosome number. M. annua sensu stricta and M. annua var. ambigua are shown tobe cytologically distinct, the former being diploid, the latterhexaploid. It is recommended that M. annua var. ambigua be regardedas a species—M. ambigua—as originally proposed byLinnaeus fils. Past investigations into the inheritance of sex are reviewedand results of further investigations into the inheritance ofmonoecism in M. annua var. ambigua are presented. Evidence obtainedsupports the hypothesis that the allosome constitution of maleplants is XXXXXY and that of monoecious plants is XXXXXX.     

Structure of the Nemertine Integument with Consideration of Its Ecological and Phylogenetic Significance

The phylum Nemertina, with more than 800 described species,occupies a wide range of habitats and figures prominently intheories of bilaterian evolution. Integuments of nemertines,from a number of habitats and representing the major orders,are compared and the general cell types constituting the epidermisare reviewed and defined. The general construction and celldemography of the integument are more or less characteristicfor each order, but are not readily generalized to lower taxonomiclevels. Similarly, the general structure of the integument hascorrelations with broad environments, but there are few conspicuous,uniquely adaptive, morphological specializations; e.g., theadhesive plate and ciliary bristles of interstitial nemertines,the tube-forming cells of Carcinonemertes epialti and variouspalaeonemertines, the epidermis of the pilidium larva. It isproposed that there are three generalized types of integumentaryglandular cells, mucous, serous and bacillary, and that theseand the ciliated cells vary only modestly across taxonomic andenvironmental lines. However, it is also proposed that the majorstructural variations of the integument not only are diagnosticfor the orders but also suggest and correlate with two majorevolutionary radiations of the extant nemertines, one epibenthic,the other infaunal—in that sequence. Similarities of thenemertine integument to that of turbellarians are superficialor at best plesiomorphous; i.e., they are also found in othertaxa.     

Physiological Adaptations of Freshwater Crayfishes that Permit Successful Aquacultural Enterprises

SYNOPSIS. There are over 400 species and three families of freshwatercrayfishes. Many species are collected for food and/or fishbait but fewer than ten are commercially cultivated. We discussthe physiological adaptations that permit these species to besuccessfully cultivated. The most important cultured speciesinclude: Northern Hemisphere—Cambaridae— Orconectesimmunis, Procambarus clarkii, and Procambarus zonangulus, andSouthern Hemisphere—Parastacidae—Cherax destructor.Procambarus clarkii is, by far, the most important species andhas been successfully introduced to all continents, save Antarcticaand Australia, from its native North America. All species maybe cultivated entirely in closed, intensive systems; however,economics are such that they are commercially produced, forthe most part, by establishing perpetuating populations in earthenpond systems. All species tolerate low oxygen, adapt well toaerial exposure, and persist for extended periods in burrowsystems in the absence of surface waters. The cultured specieshave high fecundities, rapid growth rates, and mature quickly.Aquaculture of freshwater crayfish is in its infancy. Therefore,it is likely that additional species with favorable adaptationsdiscussed here will be identified for cultural purposes     

Plant Growth-promoting Rhizobacteria and Soybean [ Glycine max (L.) Merr.] Growth and Physiology at Suboptimal Root Zone Temperatures

Application of plant growth-promoting rhizobacteria (PGPR) hasbeen shown to increase legume growth and development under optimaltemperature conditions, and specifically to increase nodulationand nitrogen fixation of soybean [Glycine max (L.) Merr.] overa range of root zone temperatures (RZTs). Nine rhizobacteriaapplied into soybean rooting media were tested for their abilityto reduce the negative effects of low RZT on soybean growthand development by improving the physiological status of theplant. Three RZTs were tested: 25, 17.5, and 15 °C. At eachtemperature some PGPR strains increased plant growth and development,but the stimulatory strains varied with temperature. The strainsthat were most stimulatory at each temperatures were as follows:15 °C—Serratia proteamaculans 1–102; 17.5 °C—Aeromonashydrophila P73, and 25 °C—Serratia liquefaciens 2–68.Because enhancement of plant physiological activities were detectedbefore the onset of nitrogen fixation, these stimulatory effectscan be attributed to direct stimulation of the plant by thePGPR rather than stimulation of plant growth via improvementof the nitrogen fixation symbiosis. Legume; nitrogen fixation; nodulation; root zone temperature; PGPR