Two new species of Haptoglossa from north-east England

Two new species of Haptoglossa , one zoosporic, H. northumbrica , and one aplanosporic, H. polymorphs, , were isolated from samples of manure and horse dung in north-east England. The zoosporic H. northumbrica is morphologically similar to H. dickii but differs in having slightly smaller infection gun cells with a unique internal arrangement of cones in the apical missile chamber. The thallus of the aplanosporic H. polymorpha is similar to H. heteromorpha but produces three different types of aplanospore. The smaller cysts either develop into broad, arcuate gun cells or form curved adhesive cells that have a rounded base. These curved adhesive cells have very different internal ultrastructural organization. The large cysts develop into infection cells that are morphologically similar to the curved adhesive cells, but their internal structure has not yet been observed.     

Cryopreservation of sperm from the coral Acropora humilis

Corals are sensitive to minute changes in their environments, and their continued existence is substantially threatened by the increasing number of destructive anthropogenic activities and unprecedented rates of climate change. Although cryopreservation has been successfully to preserve mammalian gametes for decades, coral cryopreservation was attempted for the first time less than 15 years ago, and freezing protocols exist for only a handful of coral species. The present study developed a cryopreservation protocol for the sperm of the common Indo-Pacific reef-builder Acropora humilis. Colonies of reefs of Sattahip Bay, Chonburi Province, Thailand were collected from 3 m depth with a mesh net during a spawning event. Immediately after collection, the sperm were isolated and subjected to a two-step freezing method featuring DMSO, polyethylene glycol, or methanol as the cryoprotectant. Viability and motility were assessed via a bioluminescence technique and a “computer-assisted semen analysis, and it was found that a 15-min equilibration with 2 M DMSO followed by cooling at 41.7 °C was the optimum cryopreservation protocol for A. humilis sperm. The post-thaw sperm achieved 45% fertilization success, and 35% of the fertilized eggs developed into blastopore larvae. The present optimized protocol can therefore facilitate the preservation of sperm for future propagation efforts of this species and provide an experimental platform for optimizing cryopreservation protocols for gametes of other scleractinian coral species.     

Rat Sertoli and spermatogenic cells express a similar gene, and its product is antigenically related to an outer dense fiber-associated protein.

We have previously reported that a heterodimeric protein secreted by rat Sertoli cells is antigenically related to a protein associated with outer dense fibers of the sperm tail. Therefore, we have explored the possibility that Sertoli and spermatogenic cells express a similar gene encoding a homologous protein. A Sertoli cell heterodimeric protein cDNA probe recognizes specific mRNA in pachytene and round spermatids fractionated by centrifugal elutriation; however, this specific mRNA was less prominent than in cultured Sertoli cells. In agreement with these observations, in situ hybridization experiments show that Sertoli cells are predominantly engaged in active heterodimeric protein mRNA synthesis, while meiotic prophase spermatocytes and spermatids also show significant but less abundant specific mRNA. Immunoblotting experiments demonstrate that, while Sertoli cells synthesize a heterodimeric protein consisting of two disulfide-linked components with molecular masses of 45 and 35 kD, both primary spermatocytes and round spermatids synthesize single 30 kD monomers not associated by disulfide linkage but recognized by antisera to Sertoli cell heterodimeric protein. Immunoblotting and immunogold electron microscopic studies show that antisera to Sertoli cell heterodimeric protein recognize a protein associated with outer dense fibers. This immunoreactivity was abolished by a 5-min pronase treatment, without affecting the integrity of outer dense fibers. Results of this study and previous studies demonstrate that both Sertoli and spermatogenic cells express a similar gene and that an antigenically related product encoded by this gene becomes associated with outer dense fibers during their assembly at spermiogenesis.     

Ultrastructure d'une cyanophycée aérienne calcifiée cavernicole: Geitleria calcarea Friedmann

Résumé L'ultrastructure de Geitleria calcarea Friedmann, cyanophycée filamenteuse aérienne, calcifiée et cavernicole, rarement signalée, est étudiée ici pour la première fois. La cytologie de cet organisme présente des originalités. Huit enveloppes cellulaires concentriques sont dénombrées: membrane plasmique, L I, L II, L III, L IV, enveloppe pariétale, gaine fibreuse et gaine carbonatée. La dernière est décrite à l'aide du M.E.B. Les thylacoïdes très nombreux ont une forme extrêmement contournée. Ils supportent des phycobilisomes cylindriques alternant avec des polysaccharides de même allure. L'organisation des synapses est détaillée. L'élongation est apicale et le mode de ramification est soit latéral, soit dichotomique.

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The ultrastructure of the atmophytic lime-encrusted filamentous blue-green alga Geitleria calcarea Friedmann, which grows in caves, is studied here for the first time. The cytology of this organism presents original features concerning the cellular sheath, envelopes, wall, thylacoïds and pit connections. Its filament growth is apical and its type of branching is lateral and dichotomous.

     

An anatomical study of anther development in Acorus L.: Phylogenetic implications

 Critical morphological synapomorphies have not been found in support of the Acoranan hypothesis, the molecular phylogenetic discovery that Acoranae are the basal monocots. The previously undetermined pattern of anther wall development in Acorus has been suggested to be one such character. Two main types of anther wall development have been recognized: 1) the “monocotyledonous” type, which characterizes both monocots and dicots, and 2) the “dicotyledonous” type, which is almost exclusively found among dicots. An anatomical study of anther wall development in Acorus was here undertaken using the electron microscope. Development of the anther wall in Acorus was found to be somewhat irregular or perhaps even intermediate between the two types although largely consistent with the “monocotyledonous” type. The presumed significance of anther wall development and other critical morphological characters to the Acoranan hypothesis in the absence of knowledge about the sister group to the monocots is evaluated. Received August 28, 2000 Accepted February 19, 2001     

Fine structure of early human embryos frozen with 1,2 propanediol

Previous studies by a French group (Fertil Steril 44:645–651, 1985) have shown that two-to eight-cell human embryos can survive slow freeze-thawing with propanediol in a biological freezer. These embryos were assessed for morphological appearance by phase-contrast microscopy. We assessed the structure of 25 frozen-thawed one- to 12-cell embryos, obtained from our in vitro fertilization (IVF) and GIFT programmes, by phase-contrast and electron microscopy, using the same method of cryopreservation. One-fourth of the embryos examined had all cells intact, and more than one-half the embryos had over 50% of their cells well preserved. Some of these embryos had unequal blastomeres and cytoplasmic fragments. Ultrastructural assessment revealed good preservation of fine structure in the intact blastomeres of all embryos and maintenance of cell-to-cell contacts. Most cytoplasmic organelles, cell membranes, and nuclei were well preserved compared to nonfrozen controls. The cells that were cryoinjured showed varying degrees of disorganization of the cell membrane, cytosol, and cellular membranes, including swelling and disruption of the nuclear envelope. Disruption of the zona was somewhat rare. Small cytoplasmic fragments were less prone to cryoinjury than blastomeres. The use of propanediol for embryo cryopreservation seems to be feasible; frozen embryos with more than 50% cells intact have produced 10 pregnancies after embryo transfer (Fertil Steril 46:268–272, 1986). Replacement of 17 frozen embryos in seven patients has resulted in a twin pregnancy in Singapore. However, the effects of freezing on the mitotic spindles of embryonic cells need to be investigated further.     

Ultrastrukturen Und Cytochemie Der Pellikula Und Des Apikalkomplexes Der Kineten Von Babesia Bigemina Und Babesia Ovis In Hämolymphe Und Ovar Von Zecken*,†

SYNOPSIS The term kinete is used in this paper for the cigar-shaped, motile development stages (“vermicule”) of Babesia occurring intra- and extracellularly in hemolymph and ovary (including oocytes) of vectors, hard ticks (Ixodoidea). The structure of, and cyto-chemical activities of hydrolases (acid phosphatase, nonspecific esterase) in the pellicle and the apical complex were studied at the fine-structural level in kinetes of Babesia bigemina Smith & Kilborne, in hemolymph of female Boophilus microplus Canestrini. The cytochemistry of acid hydrolases was studied also in kinetes of Babesia ovis (Babes) Starcovici, in hemolymph and ovary of Rhipi-cephultis bursa Canestrini & Fanzago. The pellicle of the B. bigemina kinetes is composed of 3 membranes (pellicular complex): an outer membrane, ?8 nm thick (the plasmalemma) and 2 inner ones, each ?6 nm thick, lying closely together. The outer membrane appears to be covered by a structureless coat, 3 nm thick. The space between the inner double membrane and the plasmalemma is 7.5 nm. The whole pellicular complex is 30 nm in diameter. The 2 inner pellicular membranes appear to be derived from the endoplasmic reticulum (ER) for the following reasons: (a) a layer of hydrolase-active material is enclosed by these membranes; (b) in the spheroid parasite stages which transform from kinetes inside hemocytes, the inner double membrane is apparently replaced by an ER cisterna; (c) the thickness of each of the inner pellicular membranes is approximately the same as that of the ER membrane. There are circular openings in the pellicular double membrane with average diameters of 100 nm; despite some similarity to micropores, they have a specific structure. The term Intrapellikularfenster (IPF) (intrapellicular windows) or pseudomicropores is proposed for these pellicular differentiations. The margin of an FPF is formed by the 2 inner membranes folding into each other; cytoplasmic, electron-dense material is accumulated alongside this edge. Unlike that of micropores, the plasmalemma of the IPF is not invaginated. The IPF appears as a single, dark ring in tangential sections. At times, rhoptry-like bodies are associated with the openings. The function of the IPF is not known. An intrapellicular opening similar to the IPF, although wider, is present at the apex of the parasite. Its margin coincides with the inner edge of the apical ring. Typical subpellicular microtubuli were not observed in the Babesia kinetes. The apical complex of the B. bigemina kinetes consists of an Apikalschirm (apical umbrella), a crown of microtubuli beneath it, and rhoptries: micronemes are also present in large numbers. The Apikalschirm is located beneath the pellicle of the apical pole of the parasite. It is a wheel-like structure composed of spokes radiating from a wide, hub-like central ring (apical ring). It should be stressed that the apical ring is not identical with the polar ring described as an integral part of the pellicular complex in other Apicomplexa. Beneath each “rib” of the Apikalschirm there is one microtubule (subcostal microtubule). In kinetes of B. ovis the “ribs” are less well developed. In addition, the Apikalschirm is more pointed in kinetes of this species in tick oocytes and ova. The rhoptries of the kinetes are spindle-shaped and largely located directly beneath the Apikalschirm. They are arranged radially, each row being associated with a “rib”. A conoid was not observed. Occasionally, low hydrolytic activity could be detected in micronemes. The rhoptries and the Apikalschirm were always negative for phosphatase and esterase activity. With regard to the number and arrangement of its membranes and to its hydrolase activity, the pellicle of the kinetes of Babesia closely resembles the pellicular complex of the Coccidia. It differs from the latter by the presence of the IFF and by the lack of micropores and of true subpellicular microtubules. In the complexity of their pellicle and in some details of the organization of their apical complex (lack of a conoid; umbrella-like structure), the kinetes of Babesia resemble the ookinetes of the Haemosporidia.