Lateral Hairs Research Articles

The role of sensory feedback from carpal sinus hairs in locomotor kinematics of rats (Rattus norvegicus, Rodentia) during walking on narrow substrates

Carpal sinus hairs on the forearms are assumed to have evolved within the stem lineage of Theria. The presence and similar position of these specialized tactile hairs in scansorial and terrestrial species as well as earlier studies on rats indicate a biological role in sensing substrate irregularities in high structured environments to ensure the dynamic stability of the body during locomotion. While these sensors were considered as one functional unit until so far, the present study deals with the biological role of the single tactile hairs of the trident, assuming a role in sensing substrate diameters and adapting limb coordination and body posture to different arboreal inclinations. To investigate the influence of each hair, we studied the locomotion of rats on poles of two different diameters whereby we selectively removed individual carpal sinus hairs. The rats walked at speeds ranging from 0.12 m/s to 0.58 m/s. Normal-light high-speed cameras and x-ray fluoroscopy visualized the hairs and body dynamics during locomotion. The time lag between first contact of the hairs to the branch until contact of the forepaw was 56–108 ms. Within this time window the pronation/supination of the paw and anterior body posture are adjusted to the substrate diameter. We presume that the most proximal sinus hair (located between the medial and lateral one) senses the paw-substrate distance through the increasing bend from its first branch-contact until the contact of the paw. The medial and the lateral hairs touch the pole sides and thereby, may collect information about the properties of the small-diameter substrate. The removal of single hairs from the group results in minor changes of kinematic parameters, but locomotor stability is seriously impaired when more than one hair is cut. The kinematic responses span from a more crouched body posture and higher forearm pronation to paw slipping, muscle tremor or complete refusal to walk on the narrow substrate.

Colonization of Brachypodium distachyon by Gluconacetobacter diazotrophicus and its effect on plant growth promotion

Gluconacetobacter diazotrophicus is a nitrogen (N) fixing bacterium originally isolated from sugarcane in Brazil. Understanding the interactions between this bacterium and plants is important to exploit the nitrogen-fixing feature of G. diazotrophicus in different crops. Research was conducted to establish, monitor and optimize methods for introducing G. diazotrophicus into Brachypodium distachyon, a model for molecular research involving monocot plants. Colonization was studied in three plant growth media including liquid, semi-solid, and solid media. The effect of mineral nitrogen on colonization was also studied in each of these three media. The colonization of B. distachyon by G. diazotrophicus was analyzed by a histochemical β-glucuronidase (GUS) assay, PCR using G. diazotrophicus specific primers and bacterial re-isolation. Colonization was established in all tested plant growth conditions. The highest level of colonization was achieved in the liquid media without mineral nitrogen. Microscopic observations showed that G. diazotrophicus colonizes B. distachyon through the lateral root emergence sites, root hairs, and root tips. The colonization was found to be limited to root tissues and not found in other organs. These results indicate that B. distachyon roots are the primary organ of interaction and colonization by the bacterium. Plant fresh weight and lateral root numbers were significantly increased in inoculated plants indicating that G. diazotrophicus can stimulate growth of B. distachyon. This study indicates that B. distachyon is a useful model to study the mechanisms of G. diazotrophicus colonization and growth enhancement in monocot plants.

First report of Arcopilus aureus causing leaf black spot disease of Pseudostellaria heterophylla in China.

Pseudostellaria heterophylla (family Caryophyllaceae) is a perennial herbaceous plant. Its tuberous roots are highly valued in traditional Chinese medicine. It is mainly cultivated in a geo-authentic production zone located in the Guizhou, Anhui, Shandong, and Fujian provinces of China (Zhao et al. 2016). The herb is widely used for treating lung diseases and as a spleen tonic (Pang et al. 2011). A severe leaf black spot disease was observed on P. heterophylla in China, from 2018 to 2020. Plants displayed water-soaking symptoms in the early stage of infection, then the watery areas turned brown-red and a black mold appeared on the lesions. At a later stage, the leaf spots showed concentric rings surrounded by a yellow halo, and the initial infection site became dry and necrotic (Supplementary Figure S1). Nine infected plants were collected from three cultivation fields in Shibing County (N 27°4'21", E 108°8'0"), Guizhou province, on April 13th, 2019. The fungus was consistently isolated from symptomatic leaves on potato dextrose agar (PDA) medium according to the method described by Larran et al (2002). A total of 22 isolates were obtained, including 7 isolates of Arcopilus and 15 isolates of Trichoderma. The growth rates of isolate MJ2-2b on PDA and oatmeal agar (OA) medium were 3 to 5 mm/day at 25 °C (Supplementary Figure S2A and S2B). Mycelium of isolate MJ2-2b was dense, yellowish-brown on PDA, while it was sparse, bright-red on OA. Also, the mycelium secreted brownish-red pigment on both PDA and OA. Ascomata when mature were water drop and limoniform. Lateral hairs were brown, erect or flexuous, tapering towards the tips. Ascospores when mature were greyish-white to grey, limoniform, or fusiform to pyriform (Supplementary Figure S2C and S2D). Further, the beta-tubulin gene (Tub2) of the fungus was amplified by using primer pairs T1 and TUB4Rd as described by Wang et al (2016) and subjected to sequencing. NCBI nucleotide BLAST results showed that sequences from seven isolates had a 99.86% identity with A. aureus (strain ChL-C, GenBank accession No. MG889987.1) (Supplementary Figure S2F). Molecular phylogenetic analysis by maximum likelihood method using MEGA 7 confirmed that the fungal isolate clustered with A. aureus. Hence, the causal agent was identified as A. aureus based on morphological and molecular characteristics. The sequence was deposited in GenBank (accession No. MW531453). Pathogenicity tests were conducted on 15-day old tissue-cultured seedlings according to Ghanbary et al (2018) (Supplementary Figure S3). Leaves of 16 seedlings were inoculated with 1×1 mm 5-day-old PDA-grown mycelial plugsof the fungal isolate. The experiment was repeated 3 times. After 10 days, the inoculated leaves showed the same symptoms observed on plants in the field. The associated fungal pathogen was consistently re-isolated from the inoculated seedlings and identified by Tub2 gene sequencing. At present, there are no reports of A. aureus causing disease of plants. To the best of our knowledge, this is the first report of leaf black spot disease on P. heterophylla caused by A. aureus in China.

A Gnotobiotic Model to Examine Plant and Microbiome Contributions to Survival under Arsenic Stress.

So far, the relative importance of the plant and its microbiome in the development of early stages of plant seedling growth under arsenic stress has not been studied. To test the role of endophytic bacteria in increasing plant success under arsenic stress, gnotobiotic seeds of J. montana were inoculated with two endophytic bacteria: Pantoea conspicua MC-K1 (PGPB and As resistant bacteria) and Arthrobacter sp. MC-D3A (non-helper and non-As resistant bacteria) and an endobacteria mixture. In holobiotic seedlings (with seed-vectored microbes intact), neither the capacity of germination nor development of roots and lateral hairs was affected at 125 μM As(V). However, in gnotobiotic seedlings, the plants are negatively impacted by absence of a microbiome and presence of arsenic, resulting in reduced growth of roots and root hairs. The inoculation of a single PGPB (P. conspicua-MCK1) shows a tendency to the recovery of the plant, both in arsenic enriched and arsenic-free media, while the inoculation with Arthrobacter sp. does not help in the recovery of the plants. Inoculation with a bacterial mixture allows recovery of plants in arsenic free media; however, plants did not recover under arsenic stress, probably because of a bacterial interaction in the mixture.

Dactylodinium arachnoides sp. nov. (Borghiellaceae, Dinophyceae): a new marine dinoflagellate with a loop-shaped apical structure complex and tubular membranous extrusomes

ABSTRACTThe morphology and phylogeny of an enigmatic marine dinoflagellate were examined using LM, SEM, TEM, and molecular phylogeny inferred from rDNA. Cells were elliptical with a conical epicone and a hemispherical hypocone. They measured c. 24.7 µm long, with a cingulum descending approximately twice its own width. Amphiesmal vesicles were thick and transparent, and were supported by translucent ridges at the suture, which were distinctive and visible by light microscopy. A large peduncle extending to the anterior was accommodated in the anterior sulcal extension. A nucleus was usually located in the hypocone, and chloroplasts were distributed peripherally. The apical structure complex was loop-shaped, originating from the right side of the anterior sulcal extension and extending upward to encircle the dorsal side of the cell apex in an anticlockwise direction. TEM showed trichocysts with lateral hairs, a pyrenoid penetrated by cytoplasmic insertions containing tubules, and an eyespot comprising globules within the chloroplast. Cells also had tubular extrusomes, unique in dinoflagellates, composed of a membrane stacked in a vesicle, and formed a long membranous tube with 2–4 finger-like terminal branches after being released from the vesicle. Molecular phylogenies showed the affinity of the species to Dactylodinium pterobelotum in the family Borghiellaceae. We propose Dactylodinium arachnoides sp. nov. for the dinoflagellate described here. It shares the characteristic traits of amphiesmal vesicles, a peduncle, a pyrenoid, and trichocysts with D. pterobelotum, whereas the number of amphiesmal vesicles, the loop-shaped apical structure complex, eyespot type A, and tubular membranous extrusomes are distinct.

First Report of Black Root Disease Caused by Chaetomium globosum on Rubber Tree Seedlings in Yunnan, China

In September 2016, a new disease of the root tips of rubber tree seedlings (Hevea brasiliensis Mull Arg.) was found in Jinghong City, Yunnan, China. Diseased seedlings had stunted, blackened, but not rotten root tips. The disease incidence at the seedbeds could reach as high as 98%. Some stems of the seedlings developed lesions or cankers, but their leaves were free of any disease symptoms. Samples of infected root tips were washed with tap water, dried, and cut into 0.2- to 0.3-cm pieces and then surface sterilized with 0.1% mercuric chloride solution for 30 s followed by three 1-min rinses with sterilized water. The pieces near the edge of the symptomatic tissues were placed on potato dextrose agar (PDA) medium and incubated at 25°C for 5 days. Such infected tissues consistently yielded a filamentous fungus with similar cultural and morphological characteristics on PDA. A representative pure culture designated as strain XJ160930 was finally obtained after several isolation transfers to PDA using a single ascospore. Strain XJ160930 had the following culture characteristics: A colony plug on 7-day PDA culture at 25°C exhibited an entire edge, with sparse white to olivaceous buff aerial hyphae when young, then without aerial hyphae and becoming citrine greenish olivaceous to gray olivaceous with fulvous, apricot to sienna exudates, or olivaceous to olivaceous gray exudates diffusing into the medium. Ascomata superficial, ostiolate, greenish olivaceous or slightly dark olivaceous buff to gray or dull green in reflected light owing to ascomatal hairs, subglobose, ovate or obovate, 110 to 240 μm diameter, and 160 to 410 µm high. Ascomatal wall brown, textura intricata in surface view. Terminal hairs finely warty, brown, erect or undulate to loosely coiled with erect or flexuous lower part, tapering and fading toward the tips, 2 to 5 μm diameter near the base. Lateral hairs brown, flexuous, fading and tapering toward the tips. Ascospores brown when mature, limoniform, usually biapiculate, bilaterally flattened, 7 to 8.5 × 5.5 to 7 μm, with an apical germ pore. Based on these morphological characteristics, the fungus was identified as Chaetomium globosum (Wang et al. 2016). To determine the pathogenicity, isolate XJ160930 was inoculated onto GT1 rubber tree seeds. Thirty seeds each were sowed in three 30-cm pots of clean sand, and 500 ml of spore suspension (1.0 × 10⁶ conidia/ml) prepared from 10-day-old culture on PDA was sprayed onto these pots. Water was used as a control treatment. All the pots were placed in a greenhouse at approximately 25 to 28°C and sprayed with sterilized water once every 3 days. After 20 days of incubation, the seeds began to germinate and grow. When these seedlings were pulled out then, all those from the fungus-inoculated pots showed root-tip stunts and darkening, like the symptoms observed in the field-infected seedlings. The pathogen was successfully isolated from the infected root tip tissues and confirmed as C. globosum by microscopic observation. No symptom was observed on the control seedlings. The experiment was repeated three times, and the same results were obtained. For molecular characterization, DNA was extracted from a pure culture of strain XJ160930 with a UNlQ-10 Column Fungal Genomic DNA Isolation Kit (Shanghai Sangon Biotech, China). A 555-bp segment of 5.8S nuclear ribosomal gene with two flanking internal transcribed spacers (ITS), a 676-bp segment of DNA dependent RNA polymerase subunit II gene region (RPB2), and a 733-bp segment of β-tubulin (TUB2) were amplified and then sequenced, using the primers ITS5/ITS4, RPB2AM-1bf/RPB2AM-7R (Miller and Huhndorf 2005), and T1 (O’Donnell and Cigelnik 1997) and TUB4Rd (Groenewald et al. 2013). The sequences, deposited in GenBank as accession numbers KY355130 (ITS), KY355133 (RPB2), and KY355135 (TUB2), showed 100, 99, and 100% sequence identity to C. globosum (GenBank HQ529775.1, KM655411.1, and KX976958.1, respectively). Therefore, both molecular and morphological analyses indicated that the pathogenic fungus was C. globosum. C. globosum has been reported to cause leaf blight disease of Chrysanthemum morifolium in Zhejiang, China (Ma et al. 2015), and decay the stem tissues of the H. brasiliensis (Wong 1988). Here, C. globosum caused failed development of the main roots in rubber seedlings, resulting in susceptibility to wind and proneness to toppling later in their lives. As far as we know, this is the first report of this pathogen involved in disease in H. brasiliensis in China occurring in the early phases of the host life.

First Report of Leaf Spot Disease Caused by Chaetomium sp. on Hevea brasiliensis in Yunnan, China

In May 2016, some irregular pink spots with gray necrosis in the center and a yellow halo around the edge were found to develop on rubber (Hevea brasiliensis) leaves in a nursery in Jinghong, Yunnan. Some infected leaves were washed with tap water, dried and sterilized with 75% alcohol for 30 s, and subsequently dried and cut into pieces of 0.2 to 0.3 cm. Finally, the heathy pieces neighbor to symptomatic leaf tissues were placed on potato dextrose agar (PDA) medium at 25°C for 5 days. Then some pure cultures identical to the colony and spores could be obtained after transferring several times. After 15 days, healthy leaves of three plants were selected for pathogenic tests in the nursery. Spore suspension (1 × 10⁶ spores/ml) was made from a pure culture 10 days after inoculation on PDA. Spore suspension (10 ml per leaf) was sprayed on the surface of the selected 10 leaves per plant; in the meantime, an equal amount of sterilized water was sprayed on another 15 healthy leaves as the controls, and then all leaves were covered respectively with a fresh bag to remain moisturize for 3 days. All the bags were removed on the 4th day after inoculation. Some light yellow spots developed, turned into red on the 7th day, and then turned into pink on 10th day. The symptoms of inoculation were consistent with those of collection in the field but not on the controls. The fungus identical to the previous colony and conidia could be reisolated from the symptomatic leaves but not from the controls. The mycelium cultured at 25°C for 5 days is light and yellow on the back, and ascospores began to appear in the colonies after 2 days. Ascus, dark brown to black, superficial, elliptic or subglobose, approximately 151 to 316 × 142 to 312 μm, the ascomal hair, setaceous, apex acuminate, separated, unbranched, brown, with smooth surface; lateral hairs are shorter, setaceous, brown, unbranched, apically acuminate, with gradually shallow color; ascus wall dispels in early stage, ascospore is brown, oval shaped to elliptic, with the size of 4.8 to 5.7 × 3.2 to 5.5 μm, one end slightly pointed with a top bud hole, flat on both sides. The internal transcribed spacer (ITS) sequence was extracted and was amplified by the primers ITS1 and ITS4, and the 563-bp product of the ITS (GenBank accession no. KX869740) showed 100% sequence identity to Chaetomium funicola (GenBank accession no. KR909159.1). Therefore, both molecular and morphological observations indicated that the pathogenic fungus was mostly similar to C. funicola (Zhang 2013). C. funicola was reported to cause chromoblastomycosis on a man’s skin in western Panama (Piepenbring et al. 2007). Chaetomium globosum could cause leaf spot on pomegranate in Yunnan, China (Guo et al. 2016). As far as the authors know, this is the first report of rubber leaf spot caused by Chaetomium sp. in Yunnan, China, as well as in the world.

Dactylodinium pterobelotum gen. et sp. nov., a new marine woloszynskioid dinoflagellate positioned between the two families Borghiellaceae and Suessiaceae.

A new marine woloszynskioid dinoflagellate Dactylodinium pterobelotum gen. et sp. nov., collected from a southern Vietnamese estuary, was described on the basis of LM, SEM, and TEM, and molecular phylogeny inferred from rDNA sequences. This species had the smallest number of amphiesmal vesicles (5 latitudinal series) in woloszynskioid dinoflagellates assigned to the Suessiaceae and Borghiellaceae. The eyespot was of type B, composed of osmiophilic globules and brick-like material, located in- and outside of the chloroplast respectively. An apical structure comprised a pair of elongate anterior vesicles (PEV). A large peduncle was conspicuous, located in the sulcal extension in the epicone, and supported by a microtubular strand of ~140 microtubules. Ultrastructural features of trichocysts represent a novel type in the Dinophyceae, bearing lateral hairs besides anterior fibers. The molecular phylogeny based on partial LSU rDNA showed the species in a basal position in the family Suessiaceae; this indicates the eyespot type B and PEV of the Borghiellaceae are ancestral states of the eyespot comprising brick-like material (type E) and an elongate apical vesicle of the Suessiaceae.

Whorled Eyebrows: A Common Facial Feature of Children with Trisomy 18

F our children with full trisomy 18 at our hospital had whorled eyebrows (Figure 1). Normally, the eyebrow hairs grow upward at an angle in the medial part, and gradually the angle becomes horizontal in the middle portion and downward at the lateral part, forming a continuous eyebrow arch. In all of our patients, however, the eyebrow at the second-third from the medial side became wide and dense, and the direction of the hair growth was the opposite, upward oblique from the lateral side. The lateral side of the eyebrow was sparse. Where the laterally growing medial hairs and the medially growing lateral hairs met at the two-thirds position of the eyebrow, a whorl was formed. When the lateral part was less sparse and grew in a more upward direction, the whorl was distinct, but

Characterization of cultivable methanotrophs from paddy soils and rice roots

Characterization of methanotrophs isolated from paddy soils and rice (Oryza sativa) roots was investigated in the present study. The number of methanotrophs in root homogenates of the rice cultivar Mutsuhomare was 4.9 × 107 most-probable-number (MPN) g−1 dry roots, in Yumeakari it was 2.0 × 108 MPN g−1 dry roots and in Kirara it was 4.6 × 107 MPN g−1 dry roots. Although bacterial cells were observed infrequently on the surface and in the interiors of roots before incubation, a large number of colonies, measuring 0.5–5 mm in diameter, were observed on the sterilized roots after incubation on nitrate mineral agar plates under methane in air. In particular, a large number of colonies were observed at the emergence sites of lateral roots and root hairs. Strains MD5-1 and M1 were isolated from the roots of Mutsuhomare and strain R62 was isolated from the root homogenate of Yumeakari. All isolates were catalase-positive and oxidase-positive, Gram-negative, straight-rod-shaped and curved-rod-shaped bacteria, and formed exospores. The isolates were able to fix nitrogen and grew in the absence of copper. In addition, all were found to be positive for naphthalene-oxidizing activities (corresponding to soluble methane mono-oxygenase activities). Strains MD5-1, M1 and R62 were closely related to Methylosinus sporium. Methanotrophic strains W3-6, SD3-5 and 2-19, isolated previously from paddy field soils, were classified into Methylosinus (W3-6) and Methylocystis (SD3-5 and 2-19) type II methanotrophs. Isolates from the rice roots (MD5-1, R62 and M1) grew logarithmically when casamino acid was used as the nitrogen source; however, the growth of these strains was reduced on the nitrate medium. These strains preferred amino acids over inorganic nitrogen as a nitrogen source for growth.

A new Tropocyclops (Copepoda, Cyclopidae) from Lake Matano, Indonesia

A new species of Tropocyclops, from the subfamily Eucyclopinae (Cyclopoida, Cyclopidae) is described on the basis of specimens recently collected from the deep waters of the ancient Lake Matano, Indonesia. Tropocyclops matanoensis n. sp., is distinguished from other species in the genus by the armature of P5 (with one seta and one spine) and the absence of lateral hairs on the somite bearing it, the antenna with only one seta on the antero-distal corner, the special shape of the seminal receptacle in female, and several other characters detailed in this study. A discussion of the genus Tropocyclops and the morphological characteristics of its representatives is given.

Life history and molecular phylogenetic relationships of Asterocladon interjectum sp. nov. (Phaeophyceae)

A small prostrate filamentous brown alga, isolated from the warm temperate Pacific coast of Japan, was cultured to investigate its life history, morphology, ultrastructure and molecular phylogenetic position. The isolate had an isomorphic, diphasic life history with anisogamous sexual reproduction. Gametogenesis was regulated by temperature and occurred only at temperatures ≤14°C. At higher temperatures, gametophytes reproduced by means of asexual zoids. All swarmers from plurilocular and unilocular zoidangia lacked an eyespot. Both sporophytes and gametophytes had oligostichous filamentous axes, lateral hairs with a basal sheath and no erect thalli. Three to eight oblong chloroplasts, each with a protruding pyrenoid, aggregated to form a stellate chloroplast configuration. All these morphological features suggested that this alga belongs to the genus Asterocladon. Plurilocular gametangia produced in an intercalary or terminal position and zoids lacking eyespots, are, however, unlike those of Asterocladon lobatum, formerly the only member of the genus. Therefore, we described the alga as a new taxon, Asterocladon interjectum sp. nov. Molecular phylogenetic analyses based on the large RUBISCO subunit (rbcL) and partial SSU nuclear ribosomal RNA gene sequences showed that A. interjectum, A. lobatum and Asteronema rhodochortonoides together formed a monophyletic clade, sister to the Ectocarpales sensu lato. Because the molecular phylogenetic analyses showed Asteronema to be paraphyletic, but monophyly of Asterocladon spp. and Asteronema rhodochortonoides was supported by the absence of cytoplasmic invaginations in pyrenoids, Asteronema rhodochortonoides was transferred to Asterocladon and an emended generic circumscription of Asterocladon was included.

P‐1 Evaluation of the influence of sex, diet and time on hair coat characteristics of cats

Skin physiology in cats has received little attention. The aim of this study was to evaluate the long‐term influence of sex, time and the level of dietary fat and energy on the dynamics and qualities of the hair coat. Twenty‐four European short‐haired laboratory cats were followed over a 1‐year period. They were divided into eight groups of three, according to: sex (12 males and 12 females), sexual status (intact or neutered) and diets [(high energy 4300 kcal/kg as fed, 21% fat) vs. (moderate energy 3500 kcal/kg as fed, 10% fat)]. Both diets were fed for 6 months to all cats following a cross‐over design. The following parameters were evaluated throughout the study: thickness of hair coat and hair lengths (neck, rump, lateral, flank), hair regrowth (after periodic clippings of 25 cm2 areas), and telogen/anagen ratio. The thickness of the hair coat initially varied from 1.2–1.7 cm on the neck, 1–1.4 cm on the rump, 1.8–2.5 cm on the flank, and hair shaft lengths were 1.7–2.5, 3.7–3.9 and 2.5–3.2 cm, respectively. Comparison of values revealed few statistical differences: increase of the thickness of hair coat in neutered cats (male and female) during the study, and increase of the length of lateral hairs in all groups during the study. Over all periods and in all groups, the curve of growth was similar (rapid then slower). Some transient variations were attributed to temporary changes in ambient conditions. In conclusion, neither sex, nutrition or season (in housed cats) influenced the general quality of hair coat, in particular hair regrowth. Funding: Royal Canin.

Guanomyces, a New Genus of Ascomycetes from Mexico

A new genus is described to accommodate a species isolated from bat dung. This fungus forms a membranous ascoma with a long neck that is or- namented with lateral glandular hairs and terminal aglandular hairs; filamentous, septate paraphyses and deliquescent asci with hyaline, unicellular ascospores are formed in the base of the centrum. In order to analyze the systematic position of this ascomycete, its morphological characters and 18S rDNA sequences were studied and compared with superficially similar species. Based on morphological and phylogenetic analysis of 18S rDNA sequences, this fungus belongs in the Sordariales and is close to but separate from Chaetomium. The hyaline ascospores, without a germ pore, and the possession of an ascoma with a long neck ornamented with lateral glandular hairs is in contrast to other genera of the Chaetomiaceae. For these reasons, the new genus Guanomyces is proposed to accommodate the new species G. polythrix in the Chaetomiaceae of the Sordariales.

Guanomyces, a new genus of Ascomycetes from Mexico

A new genus is described to accommodate a species isolated from bat dung. This fungus forms a membranous ascoma with a long neck that is ornamented with lateral glandular hairs and terminal aglandular hairs; filamentous, septate paraphyses and deliquescent asci with hyaline, unicellular ascospores are formed in the base of the centrum. In order to analyze the systematic position of this ascomycete, its morphological characters and 18S rDNA sequences were studied and compared with superficially similar species. Based on morphological and phylogenetic analysis of 18S rDNA sequences, this fungus belongs in the Sordariales and is close to but separate from Chaetomium. The hyaline ascospores, without a germ pore, and the possession of an ascoma with a long neck ornamented with lateral glandular hairs is in contrast to other genera of the Chaetomiaceae. For these reasons, the new genus Guanomyces is proposed to accommodate the new species G. polythrix in the Chaetomiaceae of the Sordariales.

Two new species of pyrenomycetous Ascomycetes from New Caledonia

Two new species of Pyrenomycetes from forest soil in New Caledonia,Anthostomella pacifica andChaetomium novaecaledonicum, are described and illustrated.Anthostomella pacifica is characterized by non-ostiolate ascomata, cylindrical asci with an amyloid apical apparatus, and two-celled ascospores (dark apical cylindrical and hyaline basal dwarfed cells) with longitudinal germ slits.Chaetomium novae-caledonicum is characterized by ostiolate ascomata, straight terminal hairs, arcuate lateral hairs with a recurved tip, and very small, ovoid-flattened ascospores.

FLAGELLAR HAIRS IN PRASINOPHYTES (CHLOROPHYTA): ULTRASTRUCTURE AND DISTRIBUTION ON THE FLAGELLAR SURFACE1

ABSTRACTThe flagellar hair ultrastructure of 16 strains of species of the prasinophycean genera Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis, Tetraselmis, Scherffelia, Pterosperma, and Pyraminonas was examined in detail by whole‐mount electron microscopy. The flagellar hairs of all genera displayed a high degree of ultrastructural complexity that was completely conserved within each strain. In all strains, flagellar hairs occurred on the sides of the flagella (lateral hairs); in several strains, special flagellar hairs also were found on the flagellar tips (tip hairs; absent in the Chlorodendrales and in Nephroselmis). Two groups of lateral hairs were distinguished: 1) T‐hairs (“Tetraselmis‐type” flagellar hairs), characterized by a smooth, tubular shaft of ca. 15 nm diameter and an overall length of 0.5–1.3 μm, and 2) Pt‐hairs (“Pterosperma‐type lateral flagellar hairs”), which were considerably longer (ca. 1.5–5.4 μm), characterized by a thick shaft of ca. 30 nm diameter, which was covered with a layer of regularly spaced small particles of ca. 10 nm diameter. In both groups of flagellar hairs, a strain‐specific number of subunits (1–101) in linear arrangement was attached to the distal end of the shaft. Tip hairs were either structurally related to T‐hairs (Mamiellales, Pseudoscourfieldia) or represented a separate group, Pt‐hairs (“Pterosperma‐type flagellar tip hairs”; Pterosperma, Pyramimonas). In four genera (Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis), both groups of lateral hairs occurred together on the same cell. Interestingly in these taxa the Pt‐hairs were exclusively attached to the shorter immature flagella (no. 2), but, in contrast, in Mantoniella and Pseudoscourfieldia the tip hairs were restricted to the longer mature flagellum (no. 1). Thus, flagella of different developmental status differ in their hair‐scale complement. The occurrence, distribution, and ultrastructure of flagellar hairs can be used to identify and classify prasinophytes at all taxonomic levels.

Somatotopic mapping of sensory neurons innervating mechanosensory hairs on the larval prolegs of Manduca sexta

The abdominal prolegs are the principal locomotory appendages of the larval tobacco hornworm, Manduca sexta. The prolegs bear numerous mechanosensory bristle sensilla, each innervated by an afferent neuron that arborizes within the central nervous system (CNS). Based on their positions on the proleg, we have divided the sensilla into planta hairs (PHs), lateral hairs (LHs), and medial hairs (MHs). Previously, we found that PH afferents produce monosynaptic excitatory postsynaptic potentials (EPSPs) in proleg retractor muscle motoneurons, the size of which depends on the position of the hair in the PH array. In this paper we examined the central arbors of the proleg afferents to determine whether there was an anatomical correlate to the pattern of synaptic strengths. We found that the afferent arbors are arranged somatotopically within the CNS in a pattern similar to that for bristle afferents elsewhere on the abdomen; i.e., the anterior-posterior and medial-lateral position of a hair on the proleg was reflected in the location of the afferent arbor along the corresponding axes within sensory neuropil. All afferents terminated within a similar ventral region of neuropil. The arbors of PH, MH, and to a lesser extent, LH afferents, were enlarged as compared to afferents innervating hairs elsewhere on the abdomen. This feature, combined with the dense innervation of the proleg, causes the proleg region to be relatively overrepresented in sensory neuropil. We also examined the afferents innervating a pair of ventral midline hairs (VMHs) present in each abdominal segment, which, unlike the other afferents, showed segment-specific central arbors. We conclude that the somatotopic mapping of afferent arbors may contribute to the specificity of synaptic connections in this system.

Transient reduction of responsiveness of blue-light-mediated hair-whorl morphogenesis inAcetabularia mediterranea induced by blue light

After a prolonged period of red light the formation of a new whorl of lateral hairs can be induced inAcetabularia mediterranea Lamouroux (=A. acetabulum (L.) Silva) by a pulse of blue light. It has previously been shown that the response to blue light obeys the law of reciprocity. In this paper we demonstrate that the responses to blue light are additive only within 10 min after the onset of blue-light treatment, since the responsiveness of the cells is also affected by blue light. One hour after a short blue-light pulse the response to a second blue-light pulse has come to a minimum. After that, the responsiveness is restored in a refractory period of several hours. The fluenceresponse curves for hair-whorl formation at the time of minimum responsiveness are shifted parallel to the original fluence-response curves without preirradiation. Again, the law of reciprocity applies. This indicates an increased light requirement only for the same degree of hair-formation response. The sensitivity to blue light of the "reduction of responsiveness" response is higher by a factor of about 50 than the "induction of hairformation" response.

Ontogenetic study of the fusion of floral organs in the normal and "solanifolia" mutant of tomato (Lycopersicon esculentum)

A comparative study on the ontogeny of the fusion of floral organs of the normal (cv. Pearson) and a single-gene mutant, "solanifolia" (sf/sf), of tomato (Lycopersicon esculentum Mill.) was conducted. In the normal, floral organs were laterally fused, although the degree and the region of fusion varied in each organ type. In the mutant, the various organs either did not fuse or, if they did, were individually recognizable. The sepals and petals of mutant flowers, unlike those of the normal, did not form a calyx cup and a corolla tube, respectively, and this was related to the limited lateral growth of mutant primordia and the absence of growth in the interprimordial region. Also, petal primordia of the mutant were narrower in width at inception. The stamens of normal flowers were fused by interweaving rows of lateral and adaxial hairs on the anthers. The mutant stamens produced lateral and adaxial hairs, yet they were free. The nonfusion of mutant stamens was related to the smaller primordium widths, greater distance between the primordia, and the larger apex diameter at the time of stamen initiation. The gynoecium of normal flowers consisted of a single ovary, style, and stigma formed by the fusion of carpel primordia. In the mutant, the gynoecium consisted of several carpels, laterally adhered to each other, and each had a recognizable style and stigma. The lack of fusion of mutant carpels was attributed to the larger apex diameter of the mutant during carpel initiation.