Phylogenetic positions of the aberrant branchiobdellidans and aphanoneurans within the Annelida as derived from 18S ribosomal RNA gene sequences

Different hypotheses have been proposed on the phylogenetic relationships of branchiobdellidans and aphanoneurans among the Annelida based on the anatomical and embryological characters. The 18S ribosomal RNA gene sequences have been analyzed from representatives of the three major taxa of the Annelida plus the branchiobdellidans and aphanoneurans to assess their phylogenetic relationships to each other. In this preliminary study, all of the phylogenetic analyses show the branchiobdellidans as a sister group to the leeches, rather than the oligochaetes. The position of the aphanoneurans is stable as an independent taxon that evolved after the polychaetes branched from the evolutionary stem, but before the ancestral oligochaetes emerged.     

Novel aspects of the nervous system of Bonellia viridis (Echiura) revealed by the combination of immunohistochemistry, confocal laser-scanning microscopy and three-dimensional reconstruction

The Echiura have been placed in close phylogenetic affinity to the Annelida on the basis of numerous homologous characters including the mode of development, the nearly identical formation of a trochophore larva, as well as the development and ultrastructure of chaetae and spermatozoa. Furthermore, phylogenetic analysis of elongation factor-1 gene sequences supports placement of the Echiura within the Annelida. Nevertheless, the Echiura are generally excluded from the Annelida due to their lack of segmentation. However, it must be considered that this lack could represent a secondary condition and that Echiura are derived from formerly segmented ancestors. In the present study, the combination of methods applied reveals several novel aspects of the central nervous system in developmental stages of Bonellia viridis. The most important of these is the metameric organization of the ventral nerve cord. Antibodies against different neurotransmitters label discrete repetitive units of perikarya in the ventral nerve cord. This organisation is additionally supported by the distribution of peripheral nerves as shown by labelling of neurotubules. These nerves are clearly paired and are evenly distributed, corresponding to the serial units of serotoninergic neurons. Different methods of computer-aided three-dimensional reconstruction display the precise spatial distribution of perikarya and peripheral nerves allowing the repetitive units to be discerned on the basis of relative size, position and number of labelled cells. The repetitive units in the nervous system of B. viridis correspond to segmental ganglia of various Annelida and are interpreted as an indication that Echiura are derived from formerly segmented ancestors, thus supporting the systematic inclusion of the Echiura within the Annelida.     

Close phylogenetic relationship between vestimentifera (tube worms) and annelida revealed by the amino acid sequence of elongation factor-lα

To clarify the phylogenetic position of Vestimentifera (tube worms), 346-bp fragments of the elongation factor-l (EF-l) gene (939–1286 according to the numbering of the human gene) of a vestimentiferan, Lamellibrachia sp., a sternaspid polychaete, Sternaspis scutata, an earthworm, Pheretima sp., and a gastropod, Alviniconcha hessleri, were sequenced. From the amino acid sequences of these EF-l, and those of two other vertebrates and two arthropods, phylogenetic relationships were deduced by the maximum likelihood (ML) method, by which the phylogenetic tree can be inferred without assuming constancy of the molecular evolutionary rate. For the ML tree and all of seven alternative trees, whose log-likelihoods could not be discriminated from that of the ML tree by the criterion of the standard error, the vestimentiferan, the polychaete, and the oligochaete formed a clade, excluding the arthropods and the gastropod as outgroups. This result is convincing evidence that Vestimentifera are protostomes that are closely related to Annelida. The ML tree suggests that Vestimentifera are more closely related to Polychaeta than to Oligochaeta, though the data were not sufficient to discriminate these three groups at a significant level. From recent evidence such as morphological characteristics and molecular information, it may safely be said that vestimentiferans should be included in the Annelida provided this phylum contains polychaetes and oligochaetes.Correspondence to: S. Kojima     

The Genetics of Dopa Decarboxylase and a-Methyl Dopa Sensitivity in Drosophila melanogaster

Dopa decarboxylase (DDC) in the Diptera is an enzyme involvedin sclerotinization of the cuticle in the epidermis and theproduction of neurogenic amines in the central nervous system.Its appearance in the epidermis at pupariation is induced bythe molting hormone ecdysone. The dietary administration ofthe analog inhibitor -methyl dopa (a MD) was used to isolateresistant and hypersensitive mutants. Two of three dominantresistant strains isolated increase DDC activity 35-70%. Forboth the increase is due to mutations between rdo (53) and pr(54.5) on the left arm of the 2nd chromosome (2L). The veryhighly resistant strain which does not affect DDC in any wayis located at 54.0 on 2L. Twelve dominant, l(2)amd^H —MD hypersensitive alleles located immediately to the right ofhk (53.9) on 2L have been recovered. All are recessive lethalsand exhibit some intracistronic complementation, and none ofthem, not even heteroallelic heterozygotes, affect DDC in anyway. The.recovery and analysis of 16 overlapping deficienciespermitted the localization of a DDC dosage effect to bands 37B10-C7on 2L; a region which includes the l(2)amd locus. Subsequentlyeight DDC deficient lethal alleles were recovered in this elevenband region which as heterozygotes reduce activities to 28–53% of controls. Some heteroallelic heterozygotes exhibit intracistroniccomplementation; most with viabilities 5% and with a mutantphenotype probably derived from inadequately sclerotinized cuticle.These Ddc alleles are within 0.004 Map Units to the right ofl(2)amd. None as Ddc/CyO heterozygotes are sensitive to -MD,and complementation occurs between the Ddc alleles and the l(2)amdalleles both on the basis of viability and DDC activity. Althoughthe protein product mutated by the l(2)amd alleles has not yetbeen identified, it seems likely that the two groups of mutantsare functionally related. Finally, the Ddc structural mutantsreduce DDC activity in the central nervous system as well asthe epidermis.     

On the ground pattern of Annelida

Annelida, traditionally divided into Polychaeta and Clitellata, are characterized by serial division of their body into numerous similar structures, the segments. In addition, there is a non-segmental part at the front end, the prostomium, and one at the back, the pygidium. New segments develop in a prepygidial proliferation zone. Each segment contains four groups of chaetae made up of β-chitin, a pair of coelomic cavities separated by mesenteries, and septa. The nervous system is a rope-ladder-like ventral nerve cord with a dorsal brain in the prostomium. For the last stem species a trochophore larva and a benthic adult are commonly postulated. There are two conflicting hypotheses describing the systematization of Annelida: the first postulates a sister-group relationship of Polychaeta and Clitellata, the second sees Clitellata as a highly derived taxon forming a subordinate taxon within the polychaetes which, consequently, are regarded as paraphyletic. Depending on the hypothesis, different characters have to be postulated for the stem species of Annelida. Besides segmentation other characters such as nuchal organs, palps and antennae, body wall musculature, cuticle, parapodia as well as structure of the central nervous system and the foregut play an important role in this discussion. Here, the different characters and character states are critically reviewed and analyzed with respect to morphology and function. The consequences for systematization of their phylogenetic interpretation as autapomorphies, synapomorphies or plesiomorphies are outlined. The resulting hypotheses are compared with those relying on molecular data sets.     

Distribution and abundance of soft-sediment meiofauna and a predatory goby in a coral reef lagoon

Spatial patterns in the abundance of the softsediment meiofauna and a predatory goby, Valenciennia longipinnis, were examined in the lagoon of One Tree Reef (Great Barrier Reef). The study provided a quantitative framework to assess the importance of physical factors on and predator prey interactions between the meiofauna and V.longipinnis. Patterns of abundance were examined at two spatial scales: among four habitats (100's of m apart) and among sites (10's of m apart) within habitats. Of the four major constituents of the meiofauna (harpacticoid copepods, nematodes, polychaetes and oligochaetes), gut analyses showed that harpacticoid copepods were the primary prey of V.longipinnis. Spatial patterns of meiofaunal abundance in the lagoon were taxon specific. Polychaetes and harpacticoid copepods exhibited significant differences among habitats. Within habitats, however, polychaetes exhibited significant differences between sites whereas copepods were uniformly distributed. Abundances of nematodes and oligochaetes did not differ between habitats. Densities of nematodes differed significantly between sites while the number of oligochaetes were similar at both spatial scales. V.longipinnis was more abundant in shallow habitats than in deep ones. This study suggests that sediment type may be an important factor influencing the distribution of both the goby and the meiofauna. V.longipinnis and two of the four meiofaunal taxa (harpacticoid copepods and polychaetes) were more abundant in the shallow habitat with fine-grained sediments. There was no significant difference between abundances of meiofaunal taxa in sites where V.longipinnis was present or absent. Overall, more fish occurred in the habitat which had the highest densities of harpacticoid copepods.     

Ethylene accumulation in waterlogged Rumex plants promotes formation of adventitious roots

Accumulation of the gaseous plant hormone ethylene is very importantfor the induction of several responses of plants to flooding.However, little is known about the role of this gas in the formationof flooding-induced adventitious roots. Formation of adventitiousroots in Rumex species is an adaptation of these plants to floodedsoil conditions. The large air-spaces in these roots enablesdiffusion of gases between shoot and roots. Application of ethylene to non-flooded Rumex plants resultedin the formation of adventitious roots. In R. palustris Sm.shoot elongation and epinasty were also observed. The numberof roots in R. thyrsiflorus Fingerh. was much lower than inR. palustris, which corresponds with the inherent differencein root forming capacity between these two species. Ethyleneconcentrations of 1.5–2µI I_{– 1} induced a maximumnumber of roots in both species. Quantification of ethylene escaping from root systems of Rumexplants that were de-submerged after a 24 h submergence periodshowed that average ethylene concentrations in submerged rootsreached 1.8 and 9.1 µl I_–1 in R. palustris and R.thyrsiflorus, respectively. Inhibition of ethylene productionin R. palustris by L--(2-aminoethoxyvinyl)-glycine (AVG) or-aminobutyric acid (AIB) decreased the number of adventitiousroots induced by flooding, indicating that high ethylene concentrationsmay be a prerequisite for the flooding-induced formation ofadventitious roots in Rumex species. Key words: Adventitious roots, epinasty, ethylene, flooding, Rumex, shoot elongation     

Immunohistochemical and ultrastructural analysis of the muscular and nervous systems in the interstitial polychaete Polygordius appendiculatus (Annelida)

The systematic position of Polygordiidae is still under debate. They have been assigned to various positions among the polychaetes. Recent molecular analyses indicate that they might well be part of a basal radiation in Annelida, suggesting that certain morphological characters could represent primitive character traits adopted from the annelid stem species. To test this hypothesis, an investigation of the muscular and nervous systems by means of immunological staining and confocal laser scanning microscopy and transmission electron microscopy was conducted. With the exception of the brain, the nervous system is entirely basiepidermal and consists of the brain, the esophageal connectives, the subesophageal region, the ventral nerve cord and several smaller longitudinal nerves. These are connected by a considerable number of ring nerves in each segment. The ventral nerve cord is made up of closely apposed longitudinal neurite bundles, a median and two larger lateral ones. Since distinct ganglia are lacking, it represents a medullary cord. The muscular system mainly consists of longitudinal fibers, regularly distributed oblique muscles and strong septa. The longitudinal fibers form a right and a left unit separated along the dorsal midline, each divided into a dorsal and ventral part by the oblique muscles. Anteriorly, the longitudinal musculature passes the brain and terminates in the prostomium. There is no musculature in the palps. In contrast to earlier observations, regularly arranged minute circular muscle fibers are present. Very likely, a basiepithelial and non-ganglionic organization of the ventral nerve cord as well as an orthogonal nervous system represent plesiomorphic characters. The same applies for the predominance of longitudinal muscle fibers.     

Nerve development, growth and differentiation during regeneration in Enchytraeus fragmentosus and Stylaria lacustris (Oligochaeta)

Enchytraeus fragmentosus (Enchytraeidae) and Stylaria lacustris (Naididae) are small terrestrial and limnetic oligochaetes that exclusively or seasonally reproduce by fragmentation and regeneration, respectively. We traced the neuronal development and differentiation during regeneration in order to gain information on the basic organization and evolution of the oligochaete nervous system. Subsequent to artificial amputation, the nervous systems have been stained with antibodies directed against acetylated alpha-tubulin. The staining was analyzed by indirect fluorescence in combination with confocal laser scanning microscopy. Both species show unique oligochaete neuronal regeneration patterns: (i) numerous fibers branch off from segmental nerves near the wound site and innervate the blastema; and (ii) the ventral cord is partly reestablished before the circumesophageal connectives develop. In the investigated 'Oligochaeta' the outgrowing fibers of the ventral nerve cord are soon bundled into at least two distinct connective pairs, which prolong into dorsal and ventral roots next to the mouth. Subsequent complete fusion of the doubled roots forms simple connectives. Thus, dorsal roots are not a unique feature for 'Polychaeta'. They occur as a transient structure in 'Oligochaeta' and might be part of the neuronal ground pattern of Annelida. The initially tetra or even pentaneuronal ventral nerve cord also differentiates into an unineuronal one by fusion.     

Cellular organization of the common nerve plexus of the body wall of the <Emphasis Type="Italic">Nephthys ciliata</Emphasis> (polychaeta) in connection with problem of relative morphofunctional autonomization of the peripheral part of the central nervous system of annelids

The study deals with neurohistological analysis of the common nerve plexus of the body wall of the polychaete Nephthys ciliata. Cellular composition and interneuronal relationships in subepidermal and intramuscular areas of the nerve plexus are demonstrated. Morphological data are presented on a possible origin of typical associative and, presumably, motor neurons located outside the abdominal ganglion on the basis of differentiating primary sensory bipolars. Axo-axonal, axo-dendritic, and axo-somatic interneuronal contacts are shown in the nerve plexus. A characteristic feature of the studied peripheral nerve plexus of the body wall of the Nephthys ciliata is emphasized: the sufficiently intensive development of associative neuronal population. This provides a structural basis for peripheral integration of nervous processes in the central nervous system of the whole animal. Small groups of sensory and associative neurons described in the present study also seem to contribute to a relative autonomization of the peripheral part of the central nervous system of Nephthys ciliata. This can also be promoted by single suggested motor neurons of the plexus. The studied nerve plexus is actually deprived of typical associative-motor neurons that are so characteristic of the abdominal ganglion of polychaetes, oligochaetes, and leeches.     

{alpha} Glucosidase activity of excised roots of Lycopersicon esculentum

Homogenates of excised roots of Lycopersicon esculentum possessboth invertase and glucosidase activity. These were separatedby Sephadex G-100 filtration and their ability to hydrolysea number of different sugars was determined. (Received May 29, 1974; )     

Sense organs and central nervous system in an enigmatic terrestrial polychaete, Hrabeiella perighndulata (Annelida)–implications for annelid evolution

Abstract. The terrestrial polychaete Hrabeiella periglandulata has many features in common with the Clitellata and the polychaete taxon Parergodrilidae. An ultrastructural investigation of the central nervous system and the sense organs of H. periglandulata individuals was undertaken to look for structural similarities with these taxa as well as to elucidate whether these structures might exhibit adaptive characters typical of terrestrial annelids in general. The central nervous system of H. periglandulata is subepidermal and consists of a brain situated in the first achaetigerous segment. The circumoesophageal connectives are without dorsal and ventral roots, and the ventral nerve cord has closely associated connectives and ill-defined ganglia. In contrast to clitellates and the terrestrial parergodrilid Parergodrilus heideri , nuchal organs are present. They are internal and highly modified compared with those of marine polychaetes but are similar to those of the intertidal parergodrilid Stygocapitella subterranea . A pair of ciliary sense organs is present inside the brain, resembling similar structures in many microdrile oligochaetes. These observations indicate that there are, in fact, structural similarities between the nervous system and the sense organs of clitellates, parergodrilids, and Hrabeiella individuals. These similarities may very likely be the result of convergent evolution in adaptation to the terrestrial environment.     

Ooplasmic segregation and axis formation in the polychaeteNereis virens embryo

Ooplasmic segregation is of great importance in the development of Annelida. The mechanisms of this process are very diverse in different groups of polychaetes, oligochaetes, and leeches (Fernandezet al., 1998). Ooplasmic segregation inNereis virens is connected with the first meiotic spindle formation and animal-vegetative axis appearance. Spherical polyaxial symmetry of the oocyte transforms into radial stratified symmetry in the course of ooplasmic segregation. There are two main steps of ooplasmic segregation inNereis virens. The first step begins after the cortical reaction when the central clear cytoplasm reaches the surface of the oocyte. The movement of the cytoplasm is sensitive to nocodazole, colchicine, and cytochalasin B and appears to be mediated by microtubules and, partly, by microfilaments. The second step is not sensitive to the microtubule inhibitors and is mediated mainly by actin filaments. Ooplasmic segregation inNereis virens may be considered as a primitive form of ooplasmic segregation in Annelida.     

Taste of methyl-{alpha}-D-mannopyranoside: Effects of cross adaptation and Gymnema sylvestre

Methyl--D-mannopyranoside is a glycoside with a bitter-sweettaste. Adaptation to sucrose reduces the sweetness and adaptationto quinine sulphate reduces the bitterness of methyl--Dmannopyranoside.Application of Gymnema sylvestre reduces the sweetness of methyl--D-mannopyranosidewithout reducing its bitterness. These results, predicted byprevious studies, contradict a recent hypothesis and reportby Birch and Mylvaganam. ¹Supported by NIH Grant 2-RO1-NS07873-9     

Early Forms of Evolution of the Basiepidermal Nerve Plexus of Bilateria as a Possible Evidence for Primary Diversity of Its Initial State

To find out whether there is a real parallelism, as it was understood by Academician A.A. Zavarzin, in the structure of the basiepidermal nerve plexus in primitive representatives of such distant groups of animals, as polychaetes and phoronids, the experimental material obtained earlier on neuronal relations in Myriochele oculata (Polychaeta, Oweniidae) and Phoronopsis harmeri (Tentaculata, Phoronoidea) was analyzed. The similarity of the basiepidermal plexus in the representatives of polychaetes and phoronids has been shown to be merely apparent and has a convergent character, i.e., it does not belong to the type of systemic parallelisms. The structural differences revealed between these two considered evolutionary initial types of nerve plexuses are supposed to be a cause of different directions of differentiation of the Bilateria nervous system. The nerve plexus structure close, by its general organization, to that of oweniids can have many common features with the basiepidermal plexus of especially primitive turbellarias and xenoturbellids, whose neuronal relations are so far non-studied. At the same time, a similar nerve plexus could originate formation of the nervous system of some archiannelids (of the nerillids type), typical polychaetes, and primitive oligochaetes. The neuronal relations similar to those of phoronids probably had more chances to progress in evolution to the direction that is principally close to the neuronal relations in pogonophoras and typical Deuterostomata (including the lower chordates).     

Ooplasmic segregation and morphological axis formation in the polychaete Nereis virens embryo

Ooplasmic segregation is of great importance in the development of Annelida. The mechanisms of this process are very diverse in different groups of polychaetes, oligochaetes, and leeches (Fernandez et al., 1998). Ooplasmic segregation in Nereis virens is connected with the first meiotic spindle formation and animal-vegetative axis appearance. Spherical polyaxial symmetry of the oocyte transforms into radial stratified symmetry in the course of ooplasmic segregation. There are two main steps of ooplasmic segregation in Nereis virens. The first step begins after the cortical reaction when the central clear cytoplasm reaches the surface of the oocyte. The movement of the cytoplasm is sensitive to nocodazole, colchicine, and cytochalasin B and appears to be mediated by microtubules and, partly, by microfilaments. The second step is not sensitive to the microtubule inhibitors and is mediated mainly by actin filaments. Ooplasmic segregation in Nereis virens may be considered as a primitive form of ooplasmic segregation in Annelida.     

Phylogeny of Annelida (Lophotrochozoa): total-evidence analysis of morphology and six genes

Background  

Annelida is one of the major protostome phyla, whose deep phylogeny is very poorly understood. Recent molecular phylogenies show that Annelida may include groups once considered separate phyla (Pogonophora, Echiurida, and Sipunculida) and that Clitellata are derived polychaetes. SThe "total-evidence" analyses combining morphological and molecular characters have been published for a few annelid taxa. No attempt has yet been made to analyse simultaneously morphological and molecular information concerning the Annelida as a whole.     

Altered fractal dynamics of gait: reduced stride-interval correlations with aging and Huntington's disease

Hausdorff, Jeffrey M., Susan L. Mitchell, RenéeFirtion, C. K. Peng, Merit E. Cudkowicz, Jeanne Y. Wei, and Ary L. Goldberger. Altered fractal dynamics of gait: reducedstride-interval correlations with aging and Huntington's disease.J. Appl. Physiol. 82(1): 262-269, 1997.Fluctuationsin the duration of the gait cycle (the stride interval) display fractaldynamics and long-range correlations in healthy young adults. Wehypothesized that these stride-interval correlations would be alteredby changes in neurological function associated with aging and certaindisease states. To test this hypothesis, we compared thestride-interval time series of 1) healthy elderly subjects andyoung controls and of 2) subjects with Huntington's diseaseand healthy controls. Using detrended fluctuation analysis, we computed, a measure of the degree to which one stride interval is correlatedwith previous and subsequent intervals over different timescales. The scaling exponent  was significantly lower in elderlysubjects compared with young subjects (elderly: 0.68 ± 0.14; young:0.87 ± 0.15; P < 0.003). The scaling exponent  wasalso smaller in the subjects with Huntington's disease compared withdisease-free controls (Huntington's disease: 0.60 ± 0.24;controls: 0.88 ± 0.17; P < 0.005). Moreover,  was linearly related to degree of functional impairment in subjects withHuntington's disease (r = 0.78, P < 0.0005).These findings demonstrate that stride-interval fluctuations are morerandom (i.e., less correlated) in elderly subjects and in subjects with Huntington's disease. Abnormal alterations in the fractal properties of gait dynamics are apparently associated with changes in central nervous system control.

     

The Interactions of Auxins and Anti-auxins in the Stimulation of Root Growth

Experiments on the interactions of auxins and anti-auxins inroots have been extended to studies with concentrations givinggrowth stimulations using 2-mm. sections excised from the extensionzone of roots of Pisum sativum. The curves relating growth responsesto log₁₀ concentration for ß-indolylacetic acid (IAA)and three anti-auxins, -(I-naphthylmethylsulphide) propionicacid (NMSP), I-naphthylmethylsulphide acetic acid (NMSA), and4-chloro-3-nitrobenzoic acid (CNB), are of very similar shape.A fourth anti-auxin, p-chlorophenoxy-iso butyric acid (PCIB),shows negligible stimulation of growth in any concentration.In multifactorial experiments involving stimulatory concentrationsof IAA (10^–4 and 10^–5 p.p.m.) with several stimulatoryconcentrations of the first three anti-auxins (NMSP, NMSA, andCNB), consistent mutual antagonisms were clearly demonstrated.PCIB in non-inhibitory concentrations markedly antagonized stimulationby IAA Similar mutual antagonisms were shown in various mixturesof two anti-auxins. Both the similarities of the concentration-response curves andthe consistent mutual antagonisms suggest that both auxins andanti-auxins in stimulating root growth are exerting identicalphysiological actions in the same growth system. On the assumptionthat these substances are active when adsorbed at some enzymeor other protoplasmic surface, it has been demonstrated thatthese experimental results are more easily explained by a directaction at those growth centres than by a competitive antagonismof a natural endogenous growth inhibitor, as suggested in aprevious paper. The bearing of these results on current theories relating auxinand anti-auxin activities to molecular structure is discussed.     

Chlorophyll fluorescence characteristics of system I chlorophyll {alpha}-protein complex and system II particles at room and liquid nitrogen temperatures

Emission spectra of a system I chlorophyll (Chl) -protein complex(SI Chl-P)³ and system II particles, prepared by the methodof Dietrich and Thornber (25), and by the method of Huzisigeet al. (24), respectively, were measured at room and liquidnitrogen temperatures to characterize the emission bands originatingfrom system I and system II. Room temperature and 77°K spectra clearly show that theF695 (690–697 nm) fluorescence band originates from bothphotosystems. In SI Chl-P the F695 band was observed both atroom and at liquid nitrogen temperatures. At 77°K, the Chl fluorescence at 685 nm is nearly as intenseas that at 720 nm (long-wavelength band) in dilute samples ofSI Chl-P. Reabsorption of 685 nm fluorescence has distortedconsiderably the shape of emission spectra of system I publishedthus far. In dilute samples of system II, the F695 is as (ormore) intense as F685, and the F735 is drastically decreased. Additionally, it is reported here that in Cyanidium caldarium,studied to compare the in vivo system with isolated SI Chl-Pand system II preparations, the 695 nm band is present uponexcitation in both system I and system II; the ratio of thelong-wave length fluorescence (F735) to the short-wavelengthfluorescence (F685) is much higher than those in the purifiedpreparations. Conceivably, the high values, obtained in thedilute samples of algae, are due to the reabsorption of thefluorescence from the short-wavelength form of Chl in the chloroplastin vivo. Furthermore, in this alga the phycocyanin fluorescenceband is split with maxima at 655 (phycocyanin) and 665 nm (allophycocyanin)at 77°K. At room temperature, however, the allophycocyaninfluorescence predominates having a peak at about 670 nm. Therelative increase in phycocyanin fluorescence at 77°K maybe due to a decrease in the energy transfer from it to allophycocyaninin agreement with slow Förster type transfer. ² Department of Botanical Sciences, University of California,Los Angeles, California 90024, U. S. A. (Received September 7, 1971; )