New species of Stygiopontius (Copepoda, Siphonostomatoida) from a deep–sea hydrothermal vent at the East Pacific Rise

Three dirivultid copepods, Stygiopontius puxillifer sp.n . and S. appositus sp.n., unusual in having pegs along the ventral edges of the cephalosome, and S. lurniger sp.n., distinguiahcd from congeners by the modificd thorn-like seta on the second segment of the maxilliped, arc dcscrihcd from a depth of 2616 m at 21°N in the eastern Pacific.     

Evidence for mate‐encounter Allee effect in an invasive longhorn beetle (Coleoptera: Cerambycidae)

1. Limited empirical support is available for mate‐encounter Allee effects in invasive insects due to the logistical challenges of studying demographic trends in low‐density populations. 2. Traps baited with pheromone and spruce volatiles were used to monitor the abundance of female Tetropium fuscum F. (Coleoptera: Cerambycidae) at multiple sites in Nova Scotia in 2011 and 2012. Each female was dissected to determine the presence or absence of sperm in its spermatheca (mated or virgin female, respectively). 3. Both male and total T. fuscum abundance declined with increasing distance to the focal point of T. fuscum's invasion. Female mating probability declined with male abundance and with distance from the invasion focus, and mating probabilities were very low at the most peripheral sites. Difficulty in encountering mates may thus contribute to limiting the spread of T. fuscum. 4. The approach outlined here could be integrated into existing surveys of wood borers using traps baited with semiochemicals to improve our understanding of the role of the mate‐encounter Allee effect in invasion dynamics.     

Melanocytes in Human Embryonic and Fetal Skin: A Review and New Findings

Melanocytes account for approximately 5–10% percent of the cells in adult epidermis. Unlike the ectodermally derived keratinocytes, they originate in the neural crest and migrate into the epidermis early in development. There has been an interest in melanocytes in developing human skin since the late 1800s, when concentrated pigmented cells were identified in the sacro-coccygeal skin of Japanese fetuses. This observation led to speculation and subsequent investigation about the racial nature of the melanocytes in this site (the Mongolian spot), the presence of melanocytes in fetuses of other races, the timing of appearance of these cells in both the dermis and epidermis, and their origin. The early investigators relied primarily on histochemical methods that stained either the premelanosome or the pigmented melanosome, or relied upon the activity of tyrosinase within the melanosome to effect the DOPA reaction. Studies by electron microscopy added further documentation to the presence of melanocytes in the skin by resolving the structure of the melanosome regardless of its state of pigmentation. All of these methods recognized, however, only differentiated melanocytes. The thorough investigations of melanocytes in the skin from a large number of black embryos and fetuses by Zimmerman and colleagues between 1948 and 1955 provided insight into the time of appearance of melanocytes in the dermis (10–11 weeks' menstrual age) and the epidermis (11–12 weeks) and revealed the density of these cells in both zones of the skin of several regions of the body. The precise localization of the melanocytes in the developing hair follicles was contributed by the studies of Mishima and Widlan (J Invest Dermatol 1966; 46:263–277). More recently, monoclonal antibodies have been developed that recognize common oncofetal or oncodifferentiation antigens on the surface or in the cytoplasm of melanoma cells and developing melanocytes (but not normal adult melanocytes). These antibodies recognize the cells irrespective of the presence or absence of melanosomes or their activity in the synthesis of pigment and therefore are valuable tools for re-examining the presence, density, and distribution patterns of melanocytes in developing human skin. Using one of these antibodies (HMB-45), it was found that dendritic melanocytes are present in the epidermis between 40 and 50 days estimated gestational age in a density comparable with that of newborn epidermis and are distributed in relatively non-random patterns. A number of questions about the influx of cells into the epidermis, potential reservoirs of melanoblasts retained within the dermis, division of epidermal melanocytes, and the interaction of melanocytes and keratinocytes during development remain unresolved. The tools now appear to be available, however, to begin to explore many of these questions.     

Genetic differentiation among populations of Caridinazebra (Decapoda: Atyidae) in tropical rainforest streams, northern Australia

1. Caridina zebra is a common atyid shrimp in some tropical rainforest streams in far north Queensland, Australia. Genetic variation at five allozyme loci was used to estimate the level of dispersal among populations of this species, within and between stream systems. Shrimps were sampled from nine streams in the Tully River catchment and two headwater streams in the adjacent Herbert River catchment in an area under consideration for extensive hydroelectric development.
2. High levels of genetic differentiation were recorded among most populations which suggests that, like other fully aquatic species, movement is limited to a very small spatial scale.
3. In the Tully catchment, populations of shrimp from streams with confluences at high altitude showed less genetic differentiation than those from streams which directly entered the lower river. Dispersal between the latter streams is clearly limited by the presence of large waterfalls and cascades.
4. Adjacent stream populations were often highly differentiated, despite their close proximity, suggesting that overland dispersal is unlikely. However, populations of shrimp in the two streams in the Herbert catchment were strikingly similar in genetic structure to those in adjacent headwater streams of the Tully. Such similarity may reflect relatively recent changes in drainage patterns.     

Changing altitude and habitat preferences of two species of wood-ant (Formica rufa and F. lugubris) in North Wales and Salop

• 1 The distribution of two species of wood-ant in Mid and North Wales was investigated.
• 2 Formica rufa L. ranges from sea level to 200 m asl and is confined to warm sites with thermally favourable substrate open to direct insolation on south facing slopes. Most sites are on abandoned smelt furnace areas which provide stabilised islands of open ground surrounded by oak scrub.
• 3 Formica lugubris Zett. tolerates more shade, can survive on north facing slopes and is found at all altitudes to 305 m asl, the approximate treeline for the region. Populations still occur in natural open oak scrub at 200–300 m but the species has extended into derelict gold, copper and lead mine sites in wooded areas and has also spread into post-1920 conifer plantations.
• 4 Upland oakwood on boulder scree near Rhayader should be preserved as an example of natural high density F.lugubris populations.
• 5 The pattern of wood-ant distribution in England and Wales matches that of coppice distribution. This in turn reflects the history of pig iron production before the Industrial Revolution. Formica rufa, widespread in the primary iron producing region of S.E. England, is concentrated further north in the secondary iron producing areas of the Forest of Dean, Wyre, N.W. Wales and the Furness district of Cumbria and North Lancashire.

     

The Physiology of Encystment of Hartmannella castellanii*

SYNOPSIS. Some aspects of the physiology of encystment of the soil amoeba Hartmannella castellanii in a replacement encystment medium consisting of 5 × 10^-2 M MgCl₂ have been investigated. It is suggested that measurement of the cellulose produced during encystment in the synthesis of the cyst wall is a more reliable measure of the process than other methods tried. The degree of encystment was dependent on the physiologic state of the amoebae and the composition of the growth medium, but the initial pH of the encystment medium (C. 4.0-8.5) had little effect on the process. The requirement for Mg during encystment was probably not due to its deficiency during growth. Encystment was inhibited to varying extents by inhibitors of protein synthesis, tetracycline and chloramphenicol and also by arsenate, arsenite and iodoacetate; sodium fluoride, malonate and 2, 4-dinitrophenol were without marked effect. Addition of glucose and α-ketoglutarate to the replacement medium led to improvement in the encystment response. The presence of glutamate and histidine during encystment led to cell death. Other carbon and nitrogen sources had no effect. During encystment there was an increase in the metabolic activity of the amoebae, as measured by their oxygen consumption. This was accompanied by a decrease of about 40% in cellular dry weight and protein content. Of the other chemical components, there were marked initial increases in the levels of total carbohydrates and pentose which were followed by their depletion during cellulose synthesis. Encystment was completed after about 64 hr when the synthesis of cellulose was complete and the oxygen uptake of the amoebae fell to an immeasurable level.     

The Action of Mercaptoethanol on Cell Division in Synchronized Tetrahymena1

SYNOPSIS. Action of mercaptoethanol (ME) on cell division and macromolecular synthesis was examined in Tetrahymena synchronized for division. Cells continuously exposed to increasingly higher concentrations of ME divided with progressively longer division delays showing a dosage-dependent response to the agent. Division was blocked in 2 × 10^?2 M ME. Many cells cytolyzed in high concentrations of ME (4 × 10^?2 M); others became spherical and motility decreased. Non-delaying concentrations of ME (2 × 10^?2 M) had little or no effect on protein synthesis but decreased DNA and RNA synthesis 10 and 35%, respectively. Blocking concentrations inhibited incorporation of phenylalanine, thymidine and uridine 35, 60, and 85%, respectively. It is suggested that the mode of action of ME is mediated thru inhibition of macromolecular synthesis essential for cell division and thru inhibition of formation of disulfide bridges between protein subunits.     

Studies on the {beta}-glucosidase System of Trifolium repens L.

Using DEAE-cellulose two distinct ß-glucosidase enzymeshave been identified in white clover; one form is primarilyassociated with the seed, the other with young leaves. Evidenceis presented for the separate nature of ß-glucosidaseand ß-galactosidase activity in dry seed flour andin young leaf tissue. These results are considered in relationto the function of the Li locus in white clover, which is shownto control both ß-glucosidase and ß-galactosidaseactivity in expanding leaves.