Congiunzioni subordinanti

Le congiunzioni subordinanti collegano la proposizione principale a quella subordinata. Le tipologie principali sono le seguenti: Causali (because, since, due to): introducono una causa, un motivo o una spiegazione dell’evento o dell’idea espressi nella proposizione principale:

Success of early treatments was marred by anaphylactic reactions and serum sickness because antibodies or antitoxins were not raised in humans. Since enzymes are biological catalysts, the equilibrium constants of catalysed reactions are not altered. Due to availability of multiple forms of acyl fatty acid chains, galactosylceramides and sulfatides show multiple isoforms.

Finali (so that, in order that, in order to): espongono il fine o lo scopo a cui tende quanto espresso nella proposizione principale:

There is an urgent need to develop new diagnostic tools so that patients can be accurately stratified at an early stage. A number of systems have been developed for the classification of cognitive and behavioural abnormalities in older people, in order that individuals at high risk of developing neurodegenerative disease may be identified well before the disease manifests clinically. Three different genetic stocks were used in order to determine the origin of the cells derived from cytoplasmic transplantations.

La congiunzione in order that appartiene a un registro formale ed è accompagnata da un verbo modale (may, might, can, could). Concessive (although, though, even though, whilst): esprimono un contrasto con l’idea formulata nella principale:

Although cells expressing insulin are detected early in human foetal development, islets isolated from foetal pancreases show poor insulin secretory responses to glucose. If dementia manifests first, the diagnosis will be DLB, even though the person could develop motor symptoms later on in the disease. Whilst for many disorders such as Alzheimer's and Parkinson's disease the cause is unknown, gene therapy is becoming the forefront of novel potential therapies described in the literature.

Comparative (rather than, as much as): esprimono un confronto tra quanto detto nella proposizione principale e nella subordinata:

Enzymes are present within a microbody-like organelle rather than adsorbed to particles. Controlled clinical studies are necessary to determine whether PLLA benefits healthy patients seeking contour restoration as much as patients seeking treatment for HIV facial lipoatrophy.

Avversative (whereas, while): introducono una contrapposizione:

In our study, some of the antibiotics increased the levels of GBL activity, whereas/while others decreased them.

Condizionali (if, unless, even if, as long as): introducono una condizione da cui dipende la validità di quanto espresso nella proposizione principale:

If cancer cells must depend almost entirely upon glycolysis for their major source of energy, any drug or protocol that can destroy or cripple glycolysis would prove efficacious for treatment. Unless patients’ preferences are explicitly sought and incorporated into clinical decision making, patients may not receive the treatment that is best for them. Oligonucleotides composed of nucleic acid mimics can become an alternative to traditional antibiotics as long as they are safely transported in human serum.

Temporali (when, before, after, still, until, whenever): situano un’azione o un evento in un punto nel tempo:

Levels of some RNA transcripts are increased when cells are exposed to extremely low frequency electric or magnetic fields. Cells from homologous rabbits or cats were seeded on coated hydrogel lenses and cultured until they reached a complete monolayer. Whenever a high concentration of the two growth factors was used, at least twice the number of cells remained in the constructs compared with controls.

Un errore comune è la tendenza a usare due congiunzioni oppure una congiunzione subordinante e un altro elemento connettivo, per esempio un avverbio:

1. Because cells are the most susceptible to DNA damage during mitosis, so this cycle leads to a remarkable time-of-day–dependent sensitivity of growing hair follicles to genotoxic stress. 2. Since cells are entrapped within the agarose matrix, therefore cell loss is prevented during staining and washing procedures.

L’esempio 1 contiene due congiunzioni, because e so. Una delle due è chiaramente di troppo e va eliminata:

Because cells are the most susceptible to DNA damage during mitosis, this cycle leads to a remarkable time-of-day–dependent sensitivity of growing hair follicles to genotoxic stress.

L’esempio 2 contiene una preposizione (since) e un avverbio di transizione (therefore). Quest’ultimo non può connettere due proposizioni e deve essere separato dal resto dell’enunciato da un segno di punteggiatura:

Cells are entrapped within the agarose matrix; therefore, cell loss is prevented during staining and washing procedures.

Alternativamente, si può optare per l’eliminazione dell’avverbio a favore della congiunzione:

Since cells are entrapped within the agarose matrix, cell loss is prevented during staining and washing procedures.

Altro aspetto a cui prestare attenzione è l’uso della punteggiatura, che dipende dalla posizione proposizione subordinata all’interno del periodo. Le congiunzioni subordinanti creano una connessione grammaticale tra la proposizione principale e la subordinata e precedono sempre quest’ultima. La proposizione subordinata, dal canto suo, può precedere o seguire la principale. Nel primo caso, le due proposizioni sono separate da una virgola:

Unless patients perceive a benefit from following a particular regimen, good glycaemic control may continue to be an elusive therapeutic goal.

Nel secondo caso, la congiunzione crea una connessione forte tra le due proposizioni, che non può essere spezzata dalla punteggiatura:

Spinal anaesthesia was performed safely unless patients had serious diseases preoperatively.

Riferimenti: Baker, Carl Lee, English Syntax, MIT Press, 2005 Heaberlin, Dick, Connecting For Coherence: A Guide to Building Sentences With Syntax and Logic, Orange House Books, 2008