The isolation of spirochaetes from the rat caecum

Spirochaetes indigenous to the conventional rat caecum were cultivated on agar medium using selective isolation techniques. The 27 axenic isolates represented four morphological types of spirochaetes differing in cell size, cell coiling pattern and number of protoplasmic flagella.     

The dispersal unit of Dacrycarpus dacrydioides (A. Rich.) de Laubenfels (Podocarpaceae) and the significance of the fleshy receptacle

FOUNTAIN, D. W., HOLDSWORTH, J. M. & OUTRED, H. A., 1989. The dispersal unit of Dacrycarpus dacrydioides (A. Rich.) de Laubenfels (Podocarpaceae) and the significance of the fleshy receptacle. Dacrycarpus dacrydioides (formerly Podocarpus dacrydioides ) is an arborescent gymnosperm endemic to New Zealand. The high water content (43%) and sensitivity of viability towards desiccation, suggest the seeds are of the 'recalcitrant' type. The 'fruits' comprising a seed borne on a fleshy receptacle arc shed in large numbers. The development of the seed precedes the full development of succulence in the receptacle and at maturity the seed has a high relative water content (RWC) relative to the receptacle. Within the maturing reproductive unit, the receptacle buffers the seed against the effects of water stress. After shedding, seeds are rapidly desiccated in moving air, and viability is impaired below approximately 80"' RWC and abolished at 34", seed RWC. The presence of the receptacle during drying confers resistance to desiccation-associated damage. Five phases of desiccation sensitivity are distinguished in recognition of the protective role of the receptacle. It is suggested that the advantages associated with prolonging seed viability may have contributed to the evolutionary development of succulence in the reproductive unit. This might be considered as a selection pressure in a manner similar to the proposal that such fleshy structures are associated with seed dispersal by birds.     

Maternal Effects on Offspring Quality in Poeciliid Fishes

SYNOPSIS. We evaluated the effects of maternal environment onoffspring size and composition in three species of poeciliidfishes. We chose food availability as the environmental factorfor study. Mature females were assigned to either high or lowfood for an interval of time, then randomly reassigned to highor low food, with the restriction that there be equal numbersin each of four treatments: high-high, high-low, lowhigh, andlow-low food availability. The three species chosen for studydiffer in the pattern of maternal provisioning. Poecilia reticulataand Priapichthys festae mothers provide all resources necessaryfor development as yolk, prior to fertilization. In contrast,Heterandria formosa mothers continue to provision the youngthroughout development. These species also differ in whetheror not they have superfetation, or the ability to carry multiplebroods of young in different stages of development. P. reticulatadoes not have superfetation while the other two species do.We were interested in whether the pattern of maternal provisioningor superfetation influenced the maternal effect. The two lecithotrophicspecies responded to low food by producing larger young withgreater fat reserves. H. formosa, the matrotrophic species,responded to low food by producing smaller young. We proposethat the production of large young in the face of low food availabilitymight represent adaptive plasticity; matrotrophy might representa constraint that prevents such an adaptive response. Superfetationhad no impact on this maternal effect.     

Micronuclear and Macronuclear Sequences of a Euplotes crassus Gene Encoding a Putative Nuclear Protein Kinase

The sequences of a 1.8-kbp macronuclear DNA molecule (V3), and the majority of its micronuclear counterpart, are reported. The macronuclear V3 DNA molecule contains an open reading frame that is interrupted by a single intron, while the micronuclear copy is interrupted by four internal eliminated sequences, one of which is located within the intron. The predicted protein product of the macronuclear V3 gene is a 471-amino acid polypeptide that is very similar to a group of protein-serine/threonine kinases from both plant and animal species, some of whose members appear to be involved in cell cycle or growth control.     

Chemical suppression of virus in cultured plant tissues

The concentrations of cucumber mosaic (CMV) and alfalfa mosaic viruses, present in various types of cultured plant tissues, were significantly less when ribavirin (syn. Virazole) at 50 or 100 mg/litre was present in the culture medium. CMV concentrations decreased within 24 days in infected cultures treated with ribabirin, but incubation periods of up to 127 days were required before the virus was undetectable. However, virus-free cultures were obtained from CMV-infected meristem-tips irrespective of the presence or absence of ribavirin. Kinetin at concentrations up to 25.6 mg/litre had no persistent antiviral effect.     

A revision of the Dip lop salts group of dinoflagellates (Dinophyceae) based on material from the British Isles

SEM has made possible a detailed re-examination of the thecal plates of marine dinoflagellates belonging to the Diplopsalis group which have been collected in an extensive survey of the seas around the British Isles. Six genera are recognized: Diplopsalis, Diplopsalopsis, Dissodium, Oblea, Zygabikodinium and die new genus and species Boreadinium pisiformis Dodge 8c Hermes. The confused taxonomic history of the group is discussed, the valid species are listed and a key for the identification of the genera is given.     

Dispersal Characteristics of Juvenile Bobcats in South-Central Indiana

ABSTRACT Bobcat (Lynx rufus) populations in the Midwestern United States experienced historic declines due to habitat loss and exploitation but have rebounded in recent decades. We investigated natal dispersal of juvenile bobcats from a population in south-central Indiana, USA, from 1999 to 2006. We radiocollared 16 juvenile bobcats (11 M, 5 F) and monitored them for 237–1,014 days (x̄ = 506). One female (20%) and 11 males (100%) dispersed from natal home ranges that averaged 14.6 km² in size. Most juveniles (70%) initiated dispersal from mid-February through March, late in their first year. Only 5 bobcats (42%) ultimately established a final home range 63 ± 35 km² in size 13–92 km (x̄ = 44) from their natal range 140 ± 45 days after initiating dispersal. Survival did not differ (P = 0.93) between dispersing (S = 0.73) and philopatric (S = 0.75) individuals, although 4 bobcats (3 M, 1 F) were killed in collisions with vehicles. We found dispersal of bobcats in fragmented landscapes is prolonged and often unsuccessful; the ability of dispersers to locate suitable vacant habitat patches may be vital to the continued growth of bobcat populations recolonizing the agricultural Midwest.     

The adipokinetic hormones of Heteroptera: a comparative study

The adipokinetic hormones (AKHs) from 15 species of heteropteran Hemiptera (encompassing eight families, six superfamilies and three infraorders) have been isolated and structurally identified using liquid chromatography coupled with mass spectrometry. None of the structures are novel and all are octapeptides. These peptide sequence data are used, together with the previously available AKH sequence data on Heteroptera, to create a larger dataset for comparative analyses. This results, in total, in AKH sequences from 30 species (spanning 13 families), which are used in a matrix confronted with the current hypotheses on the phylogeny of Heteroptera. The expanded dataset shows that all heteropterans have octapeptide AKHs; three species have two AKHs, whereas the overwhelming majority have only one AKH. From a total of 11 different AKH peptides known from Heteroptera to date, three AKHs occur frequently: Panbo‐red pigment‐concentrating hormone (RPCH) (×10), Schgr‐AKH‐II (×6) and Anaim‐AKH (×4). The heteropteran database also suggests that particular AKH variants are family‐specific. The AKHs of Heteroptera: Pentatomomorpha (all terrestrial) are not present in Nepomorpha (aquatic) and Gerromorpha: Gerridae (semiaquatic); AKHs with a Val in position 2 are absent in the Pentatomomorpha (only AKHs with Leu² are present), whereas Val² predominates in the nonterrestrial species. An unexpected diversity of AKH sequences is found in Nepomorpha, Nepoidea, Nepidae and Nepinae, whereas Panbo‐RPCH (which has been identified in all infraorders of decapod crustaceans) is present in all analysed species of Pentatomidae and also in the only species of Tessaratomidae investigated. The molecular evolution of Heteroptera with respect to other insect groups and to crustaceans is discussed     

Survival of Breeding Pacific Common Eiders on the Yukon-Kuskokwim Delta,Alaska

ABSTRACT Populations of Pacific common eiders (Somateria mollissima v-nigrum) breeding in Alaska, USA, have declined markedly over the past 40 years. We studied survival of adult female Pacific common eiders using capture—recapture of nesting hens at 3 sites on the Yukon-Kuskokwim Delta (YKD), Alaska from 1994 to 2004. We used data consisting of 268 recapture events from 361 uniquely marked individuals to investigate temporal, geographic, and environmental variation in adult female survival. Our results suggest apparent annual survival of adult eiders from the YKD was high (0.892, SE = 0.022) and spatially and temporally invariant (σ² = 0.005), a pattern consistent with other long-lived marine birds. Moreover, our results suggest adult survival may be functionally fixed for Pacific common eiders, and at the present, adult survival may be relatively unresponsive to environmental or management perturbations. Our data did not support hypothesized variation in survival relative to mortality factors such as predation on breeding grounds, physiologic costs of reproduction, and wintering conditions. Although changes in adult survival likely have a large potential effect on prospective population growth, our results suggest viable management actions aimed at increasing survival may be extremely limited.