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Myxobacteria are on order of Gram-negative, soil dwelling bacteria that feature an impressive number of properties: they can glide on solid surfaces by using two different motility motors, subsist by preying on other microorganisms, are often producers of multiple natural products, and upon adverse environmental conditions, they are able to form multicellular structures called “fruiting bodies”. The process, in which these macroscopically visible structures arise from independent single cells, has been the predominant subject of myxobacterial research for many decades. More precisely, researchers have strived for the discovery of genes, proteins and small molecules that act as signals, receivers or modulators of this complex process. In this regard, the species Myxococcus xanthus has evolved into the model organism due to its relatively simple and reliable handling in a laboratory environment. The research underlying this thesis focused on the identification and biosynthesis of lipids that may act as intercellular signaling molecules during the course of fruiting body formation of the myxobacterium Myxococcus xanthus as part of the “E-signal” system. In general, lipids containing branched-chain fatty acids with an uneven number of carbon atoms were found to be important players in this particular process. Nevertheless, their exact roles remain largely unknown as of this day. The first publication that is part of this thesis deals with an aspect that even strengthened the importance of role of iso-branched compounds in myxobacteria: myxobacterial metabolism is able to transform precursors of iso-lipids to isoprenoids. It addresses the question whether isoprenoids in general are important for fruiting body formation. Phenotypic analysis of mutants impaired in the biosynthesis of the central isoprenoid precursor 3-hydroxymethylglutaryl-Coenzyme A (3-HMG-CoA) from acetate and/or branched chain keto acids and their genetic and metabolic complementation clearly showed that isoprenoids are essential for fruiting body formation and confirmed that leucine derived isovalerate is an important source for isoprenoid precursors in myxobacteria. The second, and by far and away most tedious and sophisticated study, addressed the question as to how myxobacteria form fatty acid derived iso-branched ether lipids and to what extent they are important for fruiting body formation and sporulation. In a previous study, those unusual lipids were identified as specific biomarkers for myxobacterial development. No biochemical pathways to ether lipids specific for prokaryotes were known by then. In this study, a putative candidate gene that may be in involved in ether lipid biosynthesis was investigated. A combination of gene disruption and complementation experiments, phenotypic analysis and monitoring of ether lipid formation by means of GC-MS demonstrated its involvement in myxobacterial ether lipid biosynthesis and the importance of these lipids for the developmental process. Heterologous expression and biochemical testing of this gene together with in-silico sequence analysis and docking experiments confirmed the functions of its predicted domains. The discussion section provides an additional suggestion on how the ether bond formation is performed. Furthermore and most importantly, iso-branched ether lipids were found to be essential for sporulation but not for fruiting body formation. In summary, one or several molecules derived from an iso-branched alkylglycerol seem to play a role during sporulation in M. xanthus and a multidomain enzyme unique for myxobacteria is involved in their biosynthesis. The last manuscript addresses the complexity of lipid metabolism in myxobacteria. Prior to this work, there was limited knowledge about the exact composition of the myxobacterial lipidome and no method was available to monitor putative changes in the myxobacterial lipidome down to the single molecular species for studying lipid biosynthesis or regulation. An ultra-performance liquid chromatography coupled with mass spectrometry based method with electrospray ionization (UPLC-ESI-MS) utilizing standard equipment and a water/acetonitrile/isopropanol based eluent system proved to be geared for the construction of lipid profiles for wild type and mutant cells of M. xanthus and to show their differences. Fragmentation spectra based structure elucidation of lipid molecular species resulted in the identification of 99 molecular species comprising glycerophosphoethanolamines, glycerophosphoglycerols, glycerolipids, ceramides and ceramide phosphoinositols. The latter have never been described for any prokaryotes before. Three dimensional plots were created from the relative intensity differences of the single molecular ion species between the different samples to provide an efficient and versatile visualization of the data and enable the researcher to quickly detect differences.
In the present paper, we concentrate on (selected) Bantu and Nilotic bare-passive strategies and lay out the basis for a typology of transitive passive constructions in these languages. We argue that bare-passives constitute an optimal strategy to change prominence relations between arguments, in languages that strongly hold to the default mapping between the highest thematic role available and the grammatical subject (i.e. Spec,TP). The Nilotic and Bantu languages discussed here differ in their way of satisfying this default mapping. In particular, impersonal bare-passives satisfy it by resorting to an agentive place-holder (an indefinite subject marker) and realizing the logical agent as a lower thematic/semantic role (e.g. instrument or locative). Left-dislocation and so called 'subjectobject' reversal bare-passives realize the default matching between agent and subject in a more straightforward way, but locate the patient in a higher argument position within the inflectional domain (Spec,TopP). As argued in Hamlaoui and Makasso (2013) and Hamlaoui (2013), and in line with Noonan (1977), the present languages display a clauseinternal split between subjecthood (being the grammatical subject in Spec,TP) and topicality (being the subject of the predication, in an inflectional-domain internal Spec,TopP).
Inversion constructions in Bantu have been discussed from a variety of perspectives over the last decades. Well-known construction types include locative inversion and subject-object reversal, while more recently semantic locative inversion and instrument inversion have been described. Theoretical studies of Bantu inversion constructions have focused on different aspects of the construction, including the licensing and grammatical function, information structure properties and the formal characteristics of pre- and postverbal NPs. With respect to the status of preverbal NPs in inversion constructions, different analyses have probed the status of the NP as subject or topic, or, more recently, as the subject of a Predication relation. The present paper summarises and compares different analyses of the preverbal domain in inversion constructions and brings out empirical and conceptual similarities and differences. In addition, different analyses are related to comparative studies of Bantu inversion constructions, so as to probe how attested variation across Bantu relates to findings of different formal accounts. The paper aims to summarise current research on the preverbal domain in inversion constructions and to indicate directions for future work.
Nsong is a western Bantu language spoken in the neighbourhood of Kikwit (5°2'28"S 18°48'58"E, Kwilu District, Bandundu Province, DRC) and encoded as B85d in the New Updated Guthrie List (Maho 2009). To this B80 or Tiene-Yanzi group also belongs Mbuun, encoded as B87 by Guthrie (1971: 39) and spoken in the wider vicinity of Idiofa (4°57'35"S 19°35'40", Kwilu District, Bandundu Province, Democratic Republic of the Congo). Both languages are closely related. They share a high percentage of fundamental and other vocabulary as well as several rather atypical phonological innovations (Bostoen & Koni Muluwa 2014; Koni Muluwa 2014; Koni Muluwa & Bostoen 2012). Preliminary elicitation-based research on Mbuun has pointed out that the pre-verbal domain plays a crucial role in the marking of argument focus in Mbuun (Bostoen & Mundeke 2011, 2012). In this paper, we assess whether this is also the case in Nsong on the basis of a text corpus which the first author has been collecting, transcribing and annotating in 2013 and 2014 as part of an endangered language documentation project funded by the DoBeS program of the Volkswagen Foundation through a 3-year grant (2012-2015). More information on the project can be found on http://www.kwilubantu.ugent.be/. This Nsong text corpus exclusively consists of oral discourse and currently counts 48.022 tokens and 11.973 types. The team’s 2013 fieldwork aimed at documenting Nsong speech events in as many different cultural settings as possible. As a result, the corpus comprises different text genres, such as political speeches, historical traditions, folk music, tales, proverbs, hunting language, ceremonial language used during circumcision and twin rites, and popular biological knowledge. In line with previous research on Mbuun, we concentrate here on mono-clausal argument focus constructions, even if preliminary research has pointed out that bi-clausal focus structures are more common in the Nsong corpus.
The present paper aims at describing different pre-verbal focus strategies in Kisikongo (H16a), spoken in the vicinity of Mbanza Kongo, northern Angola. This western Bantu language is part of the Kikongo Language Cluster (KLC), stretching from southern Gabon to northern Angola, including Cabinda and parts of Congo-Brazzaville and Congo-Kinshasa. Kikongo exhibits a clause-internal pre-verbal argument focus position, which has rarely been reported in Bantu languages, except in Mbuun (B87) (Bostoen and Mundeke 2012) and Nsong (B85d) (Koni Muluwa and Bostoen, this volume), both spoken in the neighboring Kwilu region of the DRC. The more extensively studied eastern and southern Bantu languages generally have a post-verbal argument focus position (cf. Watters 1979, Morimoto 2000, Creissels 2004, Güldemann 2007, Buell 2009, van der Wal 2009, among others). In addition to this mono-clausal argument focus strategy, Kisikongo also relies on different bi-clausal constructions to focus arguments, i.e. cleft-constructions.
Nen and Nyokon are unique among the Bantu languages in allowing full nominal objects between the tense/aspect marker and the verb. Despite the fact that the two languages are neighbours and related they make different use of this positional option. In Nen the position is the default one for objects and the post-verbal position renders an object discrete and suitable for quantified objects and for contrast. In Nyokon the position before the verb is functionally equivalent to the one after the verb. The difference is related to the fact that Nyokon allows the preverbal object only in certain tenses whereas in Nen it is not restricted. But contrasted objects in Nyokon too appear after the verb. There is a construction in which both positions are filled with a constituent. This construction is modelled on a secondary predication construction.
Locative inversion in Cuwabo
(2014)
This paper proposes a detailed description of locative inversion (LI) constructions in Cuwabo, in terms of morphosyntactic properties and thematic restrictions. Of particular interest are the use of disjoint verb forms in LI, and the co-existence of formal and semantic LI, which challenges the widespread belief that the two constructions cannot be found in the same language.
This paper deals with left and right dislocation in Embɔsi, a Bantu language (C25) spoken in Congo-Brazzaville. The prosody of dislocation has gathered considerable attention, as it is particularly informative for the theories of the syntax-prosody mapping of Intonation Phrases (a.o. Selkirk, 2009, 2011; Downing, 2011). Concentrating on selected Bantu languages, Downing (2011) identifies two main phrasing patterns. She primarily distinguishes languages in which only right dislocated phrases display a lack of prosodic integration ("asymmetric" languages), from languages in which both left and right dislocations phrase separately ("symmetric" languages). Hiatus avoidance processes, boundary tones and register expansion/reduction indicate that Embɔsi displays a somewhat more intricate phrasing pattern. In this language, both left and right dislocated items sit outside of the Intonation Phrase formed by the core-clause, but only the latter form their own Intonation Phrase. We also discuss the prosody of multiple dislocations (i.e. with two dislocated arguments), which have not so far received all the attention they deserve. What we observe in Embɔsi is that either the two dislocated items phrase together and are not integrated to the core Intonation Phrase, or only the outermost dislocated element phrases separately.
Introduction
(2014)
Bantu languages have been at the heart of the research on the interaction between syntax, prosody and information structure. In these predominantly SVO languages, considerable attention has been devoted to postverbal phenomena. By addressing issues related to Subjects, Topics and Object-Verb word orders, the goal of the present papers is to deepen our understanding of the interaction of different grammatical components (syntax, phonology, semantics/pragmatics) both in individual languages and across the Bantu family. Each paper makes a valuable contribution to ongoing discussions on the preverbal domain.
It has long been observed that subjects cross-linguistically have topic properties: they are typically definite, referential and/or generic (Givón 1976). Bantu languages are said to illustrate this generalization: preverbal position for NPs is equated with both subject and topic status and postverbal position with focus (and non-subject). However, there is a growing body of work showing that preverbal subjects are not necessarily syntactically or semantically equivalent to topics. For example, Zerbian’s (2006) careful study of preverbal position in Northern Sotho shows that preverbal subjects meet few of the semantic tests for aboutness topics. The study of restrictions on preverbal subjects in Durban Zulu presented in this paper builds on Zerbian (2006) and Halpert (2012). In particular, we investigate the interpretational properties of preverbal indefinite subjects. These subjects show us that preverbal subjects carry a presupposition of existence. We explore an analysis connecting the "strong reading" of preverbal subjects with how high the verb moves in Zulu (following Tsai’s 2001 work on Mandarin).