Ionic regulation and Na+,K+-ATPase activity in gills and kidney of the Antarctic aglomerular cod icefish exposed to dilute sea water

When Notothenia neglecta was exposed to diluted, half strength, sea water for 6 h or 10 days, serum concentrations of Cl^-, Na⁺, K⁺ and Mg²⁺ did not differ from those of sea water controls. This indicates that the fish were capable of both short- and long-term regulation. Renal Na⁺,K⁺-ATPase activity decreased after a 6 h exposure to diluted sea water, but there were no differences between diluted sea water and controls after 10 days of exposure.     

Range expansion and hybridization in Round Island petrels (Pterodroma spp.): evidence from microsatellite genotypes

Historical records suggest that the petrels of Round Island (near Mauritius, Indian Ocean) represent a recent, long‐distance colonization by species originating from the Atlantic and Pacific Oceans. The majority of petrels on Round Island appear most similar to Pterodroma arminjoniana, a species whose only other breeding locality is Trindade Island in the South Atlantic. Using nine microsatellite loci, patterns of genetic differentiation in petrels from Round and Trindade Islands were analysed. The two populations exhibit low but significant levels of differentiation in allele frequencies and estimates of migration rate between islands using genetic data are also low, supporting the hypothesis that these populations have recently separated but are now isolated from one another. A second population of petrels, most similar in appearance to the Pacific species P. neglecta, is also present on Round Island and observations suggest that the two petrel species are hybridizing. Vocalizations recorded on the island also suggest that hybrid birds may be present within the population. Data from microsatellite genotypes support this hypothesis and indicate that there may have been many generations of hybridization and back‐crossing between P. arminjoniana and P. neglecta on Round Island. Our results provide an insight into the processes of dispersal and the consequences of secondary contact in Procellariiformes.     

Myxozyma neglecta sp. nov. (Candidaceae) a new yeast species from South Africa

Three strains of Myxozyma mucilagina including the type strain were reexamined. Based on differences in their carbon utilization pattern, mobility of isoenzymes, mol% G + C of their DNA and extent of DNA complementary the new species Myxozyma neglecta is proposed.     

Rough periwinkle polymorphism on the east coast of Yorkshire: comparison of RAPD-DNA data with morphotype

A genetic analysis of morphotypes of Littorina saxatilis from two locations on the north-east coast of England (Filey and Ravenscar), using randomly amplified DNA polymorphisms (RAPD) generated with a single primer, revealed quite different patterns of variation. Thin shelled, wide-apertured (H-form) animals from Ravenscar tended to cluster separately from thick shelled (M) forms, indicating genetic differentiation of these morphs. Animals of similar morphology (H and M) from Filey (about 30 km distant) did not display such an obvious pattern, and although there was still evidence of differentiation from discriminant analysis of RAPD data, levels of correct classification were reduced at Filey. This suggests that the utility of a single RAPD primer for separation of such forms varies over a relatively small distance. L. arcana from Ravenscar, included as an outgroup, were generally well differentiated from L. saxatilis and were noted to exhibit less variation, a phenomenon that has been noted previously in some allozyme and RAPD analyses. A similar RAPD analysis undertaken on small, barnacle dwelling, brooding forms from Peak Steel, Ravenscar revealed that animals appeared to have as great a tendency to cluster together on a microgeographic scale (by collection patch) as by species ( L. neglecta or L. saxatilis b) although predominance of certain species in individual patches largely explains this. Discriminant analysis of RAPD presence/absence data did correctly place over 90% of barnacle dwelling animals to their respective species, and we consider this as evidence of separate gene pools. RAPD is taken to be a useful tool for screening genetic variation in this complex of animals on a local scale when either a pre-selected informative primer is utilised or a battery of primers is used, but its efficacy may be reduced when a single primer is employed for screening animals from different shores.     

The xanthophyll cycle and acclimation of Pinus ponderosa and Malva neglecta to winter stress

Seasonal differences in the efficiency of open PSII units (F _v/F _m), leaf pigment composition and xanthophyll cycle conversion (Z+A)/(V+A+Z), leaf adenylate status, and photosynthetic capacity were investigated in Pinus ponderosa (Ponderosa pine) and Malva neglecta. In P. ponderosa, acclimation to winter involved a lower photosynthetic capacity, higher carotenoid to chlorophyll ratio, persistent reductions in F _v/F _m corresponding to persistent retention of Z+A, and no change in foliar ATP/ADP ratios. In contrast, M. neglecta characterized in winter exhibited higher rates of photosynthesis than in summer with no change in carotenoid to chlorophyll ratio, while small nocturnally persistent reductions in F _v/F _m were observed exclusively on colder winter nights when nocturnal retention of Z+A, and high ATP/ADP ratios were also present. Upon removal of winter-stressed leaves or needles from the field to room temperature, a portion of F _v/F _m relaxed within 15 min of warming and recovery was completed within 5 h in M. neglecta but required 100 h in P. ponderosa. In M. neglecta, the entire recovery of F _v/F _m correlated with decreases in the foliar ATP/ADP ratio, while in P. ponderosa this ratio remained unchanged. Possible ATP-dependent forms of sustained (Z+A)-dependent energy dissipation are discussed including a nocturnally retained pH gradient on cold winter nights. The slow recovery in pine involved not only retention of Z+A, but apparently also a persistent engagement of Z+A for energy dissipation via an unidentified mechanism. Received: 15 May 1998 / Accepted: 9 November 1998     

The chloroplast pigments of some green and yellow-green algae

Pigment analysis carried out by thin-layer chromatography confirms that Chlorocloster engadinensis Vischer, C. solani George and Nephrodiella brevis Vischer are all green algae (Chlorophyceae) and not yellow-green algae (Xanthophyceae) as has been suggested. The pigments of Coccomyxa elongata Jaag, C. simplex (Pringsheim) Mainx and Pyrobotrys stellata Korshikov are also typical of green algae. The pigments of Pleurochloris commutata Pascher, P. magna Boye Petersen, Polyedriella helvetica Vischer et Pascher, Mischococcus sphaerocephalus Vischer and Tribonema aequale Pascher, are different to those of the green algae in accordance with their being classified as yellow-green algae. However, a detailed comparison of the pigments of Pleurochloris and Tribonema suggests that whilst both contain chlorophyll, α, β-carotene and esterified vaucheriaxanthin, the major xanthophyll in Pleurochloris corresponds to violaxanthin and not to antheraxanthin as in Tribonema.     

竹叶青冈学名评注

竹叶青冈为我国南方及中南半岛常绿阔叶林常见树种,为该区域的重要材用树种。中国植物志中文版采用Cyclobalanopsis bambusifolia(Hance)Chun ex Y.C.HsuH.W.Jen作为其学名,但是基源名Quercus bambusifolia Hance由于错误鉴定1857年并未合格发表,随后基于同一模式和不同的模式,这一种加词先后多次被发表,其中涉及多个裸名、晚出同名、新名称、新组合,学名变化复杂,但其正确学名在国际权威植物分类数据库中并未采纳,正确学名在生态学等研究中亦未采用。因此,对竹叶青冈而言,其学名还存在众多疑问。为了澄清该种的学名,作者通过文献考证和标本核实查阅,对竹叶青冈学名变更历史进行追溯并根据最新的《藻类、真菌、植物国际命名法规》(简称墨尔本法规)对各变更学名进行了评述。本研究结果支持Q.neglecta(Schott.)Koidz作为竹叶青冈正确的学名。但由于国内植物学名仍以中国植物志为主要依据,而中国植物志仍采用狭义栎属Quercus s.s.的概念,为避免造成更多学名混乱,竹叶青冈的学名可沿用中国植物志英文版中学名Cyclobalanopsis neglecta,但中文版所采用C.bambusifolia为错误学名,应该弃用。     

Quantitative analyses of sex and size differences in the macula neglecta and ramus neglectus in the inner ear of the skate,Raja ocellata

Summary In Raja ocellata the macula neglecta is located in the posterior canal duct of the inner ear at the junction with the sacculus. The maximum length and width of a freeze-dried macula from a male skate of 61 cm width is 1035 m and 315 m respectively. Ultrastructural studies show that the hair cells of the macula are of two types. Orientation of hair cells is towards the periphery with a reverse direction of polarization in 5.0 to 6.5% of the cells. The axons of the associated nerve, the ramus neglectus, are myelinated, and include both efferent and afferent fibres.Electron-microscopic studies and quantitative analyses reveal significant sex differences in the macula neglecta and ramus neglectus. Hair cell and axon numbers, and total axon areas increase linearly with skate size, and are significantly different in males and females for any given representative size of skate, the females having the larger counts. Since the macula neglecta functions as a vibration detector of far-field localizations, the gender difference may be involved in the location of prey, or in mate detection. It is unknown whether such differences occur in any other vertebrate species.     

Close relationship between the state of the xanthophyll cycle pigments and photosystem II efficiency during recovery from winter stress

The potential involvement of the xanthophyll cycle in photoprotection of overwintering evergreen plants was investigated. Leaves from five evergreen species. Pseudotsuga menziesii, Pinus panderosa, Euonyums kiautschovicus. Mahonia repens and Malva neglecta, were collected from the field predawn during winter and transferred to the laboratory where chlorophyll fluorescence emission as well as the chlorophyll and carotenoid composition were ascertained periodically for 4.5 days. Leaves and needles from all species were found to have retained large amounts of the xanthophyll cycle pigments zeaxanthin and antheraxanthin, and they exhibited sustained low values of the intrinsic efficiency of photosystem II (PSII; measured as the ratio of variable to maximal fluorescence, F_v/F_m) upon collection. The increase in PSII efficiency was biphasic, with a rapid phase (requiring several hours) and a slow phase (requiring several days). Changes in the conversion state of the xanthophyll cycle were found to correlate with increases in PSII efficiency in both phases, with the latter phase involving large increases in both F_m (maximal fluorescence) and F_o (minimal fluorescence) throughout the period of recovery. The relationship between F_m quenching (expressed as nonphotochemical or Stern-Volmer quenching [NPQ] of F_m, i.e. F_m/ F_m–1) and F_o quenching (F_o/F_o–1) was linear, as expected for changes in xanthophyll cycle-dependent energy dissipation in the antenna complexes. Furthermore, the relationship between F_v/F_m and NPQ during recovery followed the theoretical relationship predicted for changes in the rate constant for energy dissipation in the antenna complexes. This fit between the theoretical relationship and the actual data indicates that all changes in NPQ or F_v/F_m can be accounted for by changes in this rate constant. The results suggest a role for the photoprotective xanthophyll cycle-dependent dissipation process in the lowered efficiency of PSII observed in coldstressed evergreen plants in the field.