Where ichthyofaunal provinces meet: the fish fauna of the Lake Edward system,East Africa

Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non-Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non-Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east-coast ichthyofaunal province.     

Secondary structure of mouse and rabbit α- and β-globin mRNAs: Differential accessibility of α and β initiator AUG codons towards nucleases

The nucleotide sequence from the 5′ terminus inward of one third of mouse α- and β^maj-globin messenger RNAs has been established. In addition, using 5′ ³²P end-labeled mRNAs as substrates and S1 and T1 nucleases as probes for single-stranded regions, the secondary structures of mouse and rabbit α- and β-globin mRNAs have been analyzed. Our results indicate that the AUG initiator codon in both mouse and rabbit β-globin mRNA is quite susceptible to cleavage with S1 and T1 nucleases, suggesting that it resides in a single-stranded exposed region. In contrast, the initiator AUG in the α-globin mRNA of both species is inaccessible to cleavage, indicating that it is either buried by tertiary structure or is base-paired. Since the rate of initiation of protein synthesis with β-globin mRNA in rabbit reticulocyte is 30–40% faster than for α-globin mRNA, these results imply a possible correlation between the differential rates of initiation with these two mRNAs and the accessibility of the respective AUG initiator codons.     

A C-type lectin from the tunicate, Styela plicata, that modulates cellular activity

Previous studies have identified proteins from tunicates (invertebrate members of the Phylum Chordata) that have physicochemical and functional properties similar to those of the inflammatory cytokine, interleukin 1 (IL-1). Here we characterize one of those proteins from the tunicate, Styela plicata, that can stimulate tunicate and mammalian cell proliferation, activate phagocytosis, increase interleukin 2 (IL-2) secretion by mammalian peripheral blood mononuclear cells and enhance IL-2 receptor (IL-2R) expression by mammalian EL-4.IL-2 cells. Partial amino acid sequence data showed that the S. plicata protein resembles three C-type lectins (TC14, TC14-1 and TC14-2) from a closely related tunicate species, Polyandrocarpa misakiensis. Its similarity to carbohydrate recognition domains (CRDs) from P. misakiensis lectins suggests that the S. plicata protein modulates the activities of mammalian immunocompetent cells by interacting with carbohydrate moieties of glycosylated cell surface receptors.     

Fluorescence lifetime,yield, energy transfer and spectrum in photosynthesis, 1950–1960*

The fluorescence lifetime of chlorophyll agives information about the primary photo-physical events in photosynthesis. Most of the light energy absorbed by chlorophylls is utilized for photochemistry. There are two main additional pathways competing for the absorbed light energy: fluorescence and radiationless internal conversion (heat). Only a few percent of the absorbed energy proceeds along these two pathways. This historical minireview focuses on the first direct measurements of the lifetime of chlorophyll fluorescence, the time it takes to transfer energy from phycoerythrin to chlorophyll a, and the discovery of the fluorescence band at 720 nm (F720; then attributed to a dimer of chlorophyll). These works were carried out during the the late 1950s to the early 1960s in the laboratory of Professor Eugene Rabinowitch at the University of Illinois, Urbana-Champaign [Brody (1995) Photosynth Res 43: 67–74]. This Minireview is dedicated to Professor Eugene Rabinowitch (1901–1973), mentor of the author (Steve Brody) as well as of the editor, and authors classmate (Govindjee). The career and contributions of Eugene Rabinowitch are available in a dedication by Bannister (1972). This revised version was published online in June 2006 with corrections to the Cover Date.     

Affixing the O to Rubisco: discovering the source of photorespiratory glycolate and its regulation

The source of glycolate in photorespiration and its control, a particularly active and controversial research topic in the 1970s, was resolved in large part by several discoveries and observations described here. George Bowes discovered that the key carboxylation enzyme Rubisco (ribulosebisphosphate carboxylase/oxygenase) is competitively inhibited by O₂ and that O₂ substitutes for CO₂ in the initial `dark' reaction of photosynthesis to yield glycolate-P, the substrate for photorespiration. William Laing derived an equation from basic enzyme kinetics that describes the CO₂, O₂, and temperature dependence of photosynthesis, photorespiration, and the CO₂ compensation point in C₃ plants. Jerome Servaites established that photosynthesis cannot be increased by inhibiting the photorespiratory pathway prior to the release of photorespiratory CO₂, and Douglas Jordan discovered substantial natural variation in the Rubisco oxygenase/carboxylase ratio. A mutant Arabidopsis plant with defective glycolate-P phosphatase, isolated by Chris Somerville, definitively established the role of O₂ and Rubisco in providing photorespiratory glycolate. Selection techniques to isolate photorespiration-deficient plants were devised by Jack Widholm and by Somerville, but no plants with reduced photorespiration were found. Somerville's approach, directed mutagenesis of Arabidopsis plants, was subsequently successful in the isolation of numerous other classes of mutants and revolutionized the science of plant biology. This revised version was published online in August 2006 with corrections to the Cover Date.     

Apparatus and mechanism of photosynthetic oxygen evolution: a personal perspective*

This historical minireview describes basic lines of progress in our understanding of the functional pattern of photosynthetic water oxidation and the structure of the Photosystem II core complex. After a short introduction into the state of the art about 35 years ago, results are reviewed that led to identification of the essential cofactors of this process and the kinetics of their reactions. Special emphasis is paid on the flash induced oxygen measurements performed by Pierre Joliot (in Paris, France) and Bessel Kok (Baltimore, MD) and their coworkers that led to the scheme, known as the Kok-cycle. These findings not only unraveled the reaction pattern of oxidation steps leading from water to molecular oxygen but also provided the essential fingerprint as prerequisite for studying individual redox reactions. Starting with the S. Singer and G. Nicolson model of membrane organization, attempts were made to gain information on the structure of the Photsystem II complex that eventually led to the current stage of knowledge based on the recently published X-ray crystal structure of 3.8 A resolution in Berlin (Germany).With respect to the mechanism of water oxidation, the impact of Gerald T. Babcock's hydrogen abstractor model and all the considerations of electron/proton transfer coupling are outlined. According to my own model cosiderations, the protein matrix is not only a 'cofactor holder' but actively participates by fine tuning via hydrogen bond networks, playing most likely an essential role in water substrate coordination and in oxygen-oxygen bond formation as the key step of the overall process.     

Period-four oscillations of the flash-induced oxygen formation in photosynthesis*

In this minireview, the earlier researches that led to the discovery of the period-four oscillations of the flash-induced oxygen formation are presented. It also includes the background of the classical model proposed by Bessel Kok, in which the formation of oxygen requires the sequential accumulation of four positive charges on the donor side of the same reaction center. This revised version was published online in August 2006 with corrections to the Cover Date.     

Limnology of Crater Lakes in Los Tuxtlas,Mexico

Investigations on the abundance, biomass and position of heterotrophic flagellates (HF) in the benthic microbial food web of a melt water stream on King George Island, Antarctic Peninsula, were undertaken during the Antarctic summer from 23rd December 1997 until 13th March 1998. Abundance and biomass of potential HF resources (picophotoautotrophic and non-photoautotrophic bacteria) as well as potential predators on HF (ciliates and meiofauna) were also investigated. HF abundance ranged from approximately 9 × 10³ to 81 × 10³ cells cm^–3, values which fall into the same range as those found in lower latitudes. Numerically important benthic HF were euglenids, kinetoplastids, thaumatomastigids and especially chrysomonads. Most species identified have been shown to have a worldwide distribution. Abundance of the benthic ciliates ranged from 27 to 950 cells cm^–3. Mean bacterial abundance was 1.9 × 10⁷ and 5.2 × 10⁸ cells cm^–3 for picophotoautotrophic and non-photoautotrophic benthos, respectively. The well-developed microbial community was able to support the large number of nematods, gastotrichs, tardigrads and rotifers with abundances reaching more than 1000 individuals cm^–3. The largest portion of heterotrophic biomass was formed by the meiofauna with a mean of 63 g C cm^–3, followed by that of the heterotrophic bacteria with 4.80 g C cm^–3. Picophotoautotrophic bacteria contributed a mean of 1.37 g C cm^–3. HF and ciliates mean biomass was 0.61 and 1.99 g C cm^–3, respectively, with the HF biomass comprising between <10 and 70% of the total protozoan biomass. The data obtained in this study identify the melt water stream as a hot-spot of heterotrophic microbial and meiofaunal activity during the austral summer. The HF in the melt water stream formed a diverse group in terms of taxa and potential feeding types. Chrysomonads, kinetoplastids, euglenids and thaumatomastigida were the most abundant taxa. A classification into feeding types identified an average of 34% of the total HF as bacterivorous while all others were able to utilise other, larger organisms as resources. Potential trophic interactions between HF and bacteria and higher trophic levels are discussed.     

Civic Biology and the Origin of the School Antievolution Movement

In discussing the origins of the antievolution movement in American high schools within the framework of science and religion, much is overlooked about the influence of educational trends in shaping this phenomenon. This was especially true in the years before the 1925 Scopes trial, the beginnings of the school antievolution movement. There was no sudden realization in the 1920’s – sixty years after the Origin of Species was published – that Darwinism conflicted with the Bible, but until evolution was being taught in the high schools, there was no impetus to outlaw it. The creation of “civic biology” curricula in the late 1910’s and early 20’s, spearheaded by a close-knit community of textbook authors, brought evolution into the high school classroom as part of a complete reshaping of “biology” as a school subject. It also incorporated progressive ideologies about the purposes of compulsory public education in shaping society, and civic biology was fundamentally focused on the applications of the life sciences to human life. Antievolution legislation was part of a broader response to the ideologies of the new biology field, and was a reaction not only to the content of the new subject, but to the increasingly centralized control and regulation of education. Viewing the early school antievolution movement through the science-religion conflict is an artifact of the Scopes trial’s re-creation of its origins. What largely caused support for␣the school antievolution movement in the South and particularly Tennessee were concerns over public education, which biology came to epitomize.     

南极乔治王岛菲尔德斯半岛和阿德雷岛地衣研究 Ⅱ.石蕊属(Cladonia)(英文)

本文第一作者在参加南极长城站地区科学考察中在乔治王岛菲尔德斯半岛和阿德雷岛采集了大量地衣标本。从形态与化学相结合研究了该地区大型地衣中种类最多的石蕊属,共计12个分类单位,多于国际上有关学者在该地区报道的石蕊属地衣种类。其中,Cl．deformis,Cl．carneola,和Cl．weymouthii等3个种是南设特兰群岛的新记录;Cl.chlorophaea是乔治王岛和阿德雷岛的新记录。Cl．cornuta,Cl．pyxidata和Cl．squamosa等3个种是阿德雷岛的新记录。其余5个分类单位即Cl.borealis,Cl．fimbriata,Cl．gracilissubsp．elongata,Cl．novochlorophaea和Cl．sarmentosa是该地区过去的已知种。记叙和讨论了每个种与邻近种之间的异同,地衣化学和在南极地区的分布。在本研究地区没有发现石蕊科地衣中的其它属。